@article{deans_taniguchi_chandrashaker_ptaszek_lindsey_2016, title={Complexity in structure-directed prebiotic chemistry. Reaction bifurcation from a beta-diketone in tetrapyrrole formation}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84979074707&partnerID=MN8TOARS}, DOI={10.1039/c6nj00545d}, abstractNote={An unsymmetrical β-diketone with δ-aminolevulinic acid affords both a “defective” and a “normal” pyrrole; upon combinatorial reaction the former terminates chain-growth of the latter on the path to tetrapyrrole macrocycles.}, number={7}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Deans, Richard M. and Taniguchi, Masahiko and Chandrashaker, Vanampally and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2016}, month={Jul}, pages={6434–6440} }
 @article{deans_taniguchi_chandrashaker_ptaszek_chambers_soares_lindsey_2016, title={Complexity in structure-directed prebiotic chemistry. Unexpected compositional richness from competing reactants in tetrapyrrole formation}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84979079544&partnerID=MN8TOARS}, DOI={10.1039/c6nj00543h}, abstractNote={Acyclic reactants afford “partially defective” pyrroles that interfere with chain growth of “normal” pyrroles on the path to tetrapyrrole macrocycles.}, number={7}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Deans, Richard M. and Taniguchi, Masahiko and Chandrashaker, Vanampally and Ptaszek, Marcin and Chambers, Dana R. and Soares, Ana R. M. and Lindsey, Jonathan S.}, year={2016}, month={Jul}, pages={6421–6433} }
 @article{taniguchi_deans_chandrashaker_ptaszek_lindsey_2016, title={Scope and limitations of two model prebiotic routes to tetrapyrrole macrocycles}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84984911595&partnerID=MN8TOARS}, DOI={10.1039/c6nj01423b}, abstractNote={Aqueous reaction (35 °C, 72 h) of two acyclic compounds, an α-aminoketone + β-ketoester or β-diketone (not shown), affords a pyrrole that self-condenses to give the porphyrinogen.}, number={9}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Taniguchi, Masahiko and Deans, Richard M. and Chandrashaker, Vanampally and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2016}, pages={7445–7455} }
 @article{chandrashaker_ptaszek_taniguchi_lindsey_2016, title={Synthesis of diverse acyclic precursors to pyrroles for studies of prebiotic routes to tetrapyrrole macrocycles}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84990050463&partnerID=MN8TOARS}, DOI={10.1039/c6nj02048h}, abstractNote={Some 50 ketones, β-diketones, β-ketoesters and α-aminoketones have been prepared for studies of the formation of trisubstituted pyrroles equipped for self-condensation leading to tetrapyrrole macrocycles.}, number={10}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Chandrashaker, Vanampally and Ptaszek, Marcin and Taniguchi, Masahiko and Lindsey, Jonathan S.}, year={2016}, pages={8786–8808} }
 @article{faries_diers_springer_yang_ptaszek_lahaye_krayer_taniguchi_kirmaier_lindsey_et al._2015, title={Photophysical Properties and Electronic Structure of Chlorin-Imides: Bridging the Gap between Chlorins and Bacteriochlorins}, volume={119}, ISSN={["1520-5207"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84934319596&partnerID=MN8TOARS}, DOI={10.1021/jp511257w}, abstractNote={Efficient light harvesting for molecular-based solar-conversion systems requires absorbers that span the photon-rich red and near-infrared (NIR) regions of the solar spectrum. Reported herein are the photophysical properties of a set of six chlorin-imides and nine synthetic chlorin analogues that extend the absorption deeper (624-714 nm) into these key spectral regions. These absorbers help bridge the gap between typical chlorins and bacteriochlorins. The new compounds have high fluorescence quantum yields (0.15-0.34) and long singlet excited-state lifetimes (4.2-10.9 ns). The bathochromic shift in Qy absorption is driven by substituent-based stabilization of the lowest unoccupied molecular orbital, with the largest shifts for chlorins that bear an electron-withdrawing, conjugative group at the 3-position in combination with a 13,15-imide ring.}, number={24}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Faries, Kaitlm M. and Diers, James R. and Springer, Joseph W. and Yang, Eunkyung and Ptaszek, Marcin and Lahaye, Dorothee and Krayer, Michael and Taniguchi, Masahiko and Kirmaier, Christine and Lindsey, Jonathan S. and et al.}, year={2015}, month={Jun}, pages={7503–7515} }
 @article{liu_ptaszek_mass_minkler_sommer_bhaumik_lindsey_2014, title={Regioselective beta-pyrrolic electrophilic substitution of hydrodipyrrin-dialkylboron complexes facilitates access to synthetic models for chlorophyll f}, volume={38}, number={4}, journal={New Journal of Chemistry}, author={Liu, M. R. and Ptaszek, M. and Mass, O. and Minkler, D. F. and Sommer, R. D. and Bhaumik, J. and Lindsey, J. S.}, year={2014}, pages={1717–1730} }
 @article{chandrashaker_taniguchi_ptaszek_lindsey_2012, title={Competing Knorr and Fischer-Fink pathways to pyrroles in neutral aqueous solution}, volume={68}, ISSN={["0040-4020"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84863630235&partnerID=MN8TOARS}, DOI={10.1016/j.tet.2012.05.080}, abstractNote={Abstract A proposed chemical model for the prebiogenesis of tetrapyrrole macrocycles relies on the condensation of a 3-alkyl-substituted 2,4-diketone and an α-aminoketone to form a pyrrole equipped for subsequent self-condensation leading to porphyrinogens. The condensation of acyclic reactants can proceed via competing Knorr (desired) and Fischer–Fink (undesired) pathways. Here, the Knorr and Fischer–Fink pathways are quantitated using (1) analogues of those in the proposed prebiotic route wherein the resulting pyrroles are blocked from subsequent condensation, and (2) a set of internal standards for quantitation of crude reaction mixtures by 1H NMR spectroscopy following extraction into CS2. The reaction of 1-amino-2-butanone and 3-methyl-2,4-pentanedione at 60 °C in aqueous solution at pH 7 for 24 h afforded the Knorr pyrrole and Fischer–Fink pyrrole in yields of 48% and 7%, respectively. The reaction in hot aqueous acid (pH 4.6, reflux, 30 min) afforded the Knorr pyrrole in diminished yield (22%) relative to that of the Fischer–Fink pyrrole (11%). The Knorr pyrrole (4-ethyl-2,3-dimethylpyrrole) is evanescent whereas the Fischer–Fink pyrrole (2,3,4-trimethyl-5-propanoylpyrrole) is quite stable; hence, rapid analysis of the reaction mixture (vs workup and isolation) is essential for accurate analysis.}, number={34}, journal={TETRAHEDRON}, publisher={Elsevier BV}, author={Chandrashaker, Vanampally and Taniguchi, Masahiko and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2012}, month={Aug}, pages={6957–6967} }
 @article{lindsey_chandrashaker_taniguchi_ptaszek_2011, title={Abiotic formation of uroporphyrinogen and coproporphyrinogen from acyclic reactants}, volume={35}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650436322&partnerID=MN8TOARS}, DOI={10.1039/c0nj00716a}, abstractNote={Tetrapyrrole 
 macrocycles (e.g., porphyrins) have long been proposed as key ingredients in the emergence of life, yet plausible routes for forming their essential pyrrole precursor have previously not been identified. Here, the anaerobic reaction of δ-aminolevulinic acid (ALA, 5–240 mM) with 5-methoxy-3-(methoxyacetyl)levulinic acid (1-AcOH, 5–240 mM) in water (pH 5–7) at 25–85 °C for a few hours to a few days affords uroporphyrinogen, which upon chemical oxidation gives uroporphyrin in overall yield of up to 10%. The key intermediate is the α-methoxymethyl-substituted analogue of the pyrrole porphobilinogen (PBG). Reaction of ALA and the decarboxy analogue of 1-AcOH (1-Me) gave coproporphyrinogen (without its biosynthetic precursor uroporphyrinogen as an intermediate); oxidation gave the corresponding coproporphyrin in yields comparable to those for uroporphyrin. In each case a mixture of porphyrin isomers was obtained, consistent with reversible oligopyrromethane formation. The route investigated here differs from the universal extant biosynthetic pathway to tetrapyrrole macrocycles, where uroporphyrinogen (isomer III) – nature's last common precursor to corrins, heme, and chlorophylls – is derived from eight molecules of ALA (via four molecules of PBG). The demonstration of the spontaneous self-organization of eight acyclic molecules to form the porphyrinogen under simple conditions may open the door to the development of a chemical model for the prebiogenesis of tetrapyrrole macrocycles.}, number={1}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Lindsey, Jonathan S. and Chandrashaker, Vanampally and Taniguchi, Masahiko and Ptaszek, Marcin}, year={2011}, pages={65–75} }
 @article{mass_pandithavidana_ptaszek_santiago_springer_jiao_tang_kirmaier_bocian_holten_et al._2011, title={De novo synthesis and properties of analogues of the self-assembling chlorosomal bacteriochlorophylls}, volume={35}, number={11}, journal={New Journal of Chemistry}, author={Mass, O. and Pandithavidana, D. R. and Ptaszek, M. and Santiago, K. and Springer, J. W. and Jiao, J. Y. and Tang, Q. and Kirmaier, C. and Bocian, D. F. and Holten, D. and et al.}, year={2011}, pages={2671–2690} }
 @article{mass_taniguchi_ptaszek_springer_faries_diers_bocian_holten_lindsey_2011, title={Structural characteristics that make chlorophylls green: interplay of hydrocarbon skeleton and substituents}, volume={35}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78650499742&partnerID=MN8TOARS}, DOI={10.1039/c0nj00652a}, abstractNote={Understanding the effects of substituents on natural photosynthetic pigments is essential for gaining a deep understanding of why such pigments were selected over the course of evolution for use in photosynthetic systems. This knowledge should provide for a more thoughtful design of artificial light-harvesting systems. The hydrocarbon skeleton of all chlorophylls is phorbine, which contains an annulated five-membered (isocyclic) ring in addition to the reduced pyrrole ring characteristic of chlorins. A phorbine and a 131-oxophorbine (which bears an oxo group in the isocyclic ring) were synthesized as benchmark molecules for fundamental spectral and photophysical studies. The phorbine and 131-oxophorbine macrocycles lack peripheral substituents other than a geminal dimethyl group in the reduced ring to stabilize the chlorin chromophore. The spectral properties and electronic structure of the zinc or free base 131-oxophorbine closely resemble those of the corresponding analogues of chlorophyll a. Accordingly, the fundamental electronic properties of chlorophylls are primarily a consequence of the 131-oxophorbine base macrocycle.}, number={1}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Mass, Olga and Taniguchi, Masahiko and Ptaszek, Marcin and Springer, Joseph W. and Faries, Kaitlyn M. and Diers, James R. and Bocian, David F. and Holten, Dewey and Lindsey, Jonathan S.}, year={2011}, pages={76–88} }
 @article{ptaszek_lahaye_krayer_muthiah_lindsey_2010, title={De Novo Synthesis of Long-Wavelength Absorbing Chlorin-13,15-dicarboximides}, volume={75}, ISSN={["1520-6904"]}, DOI={10.1021/jo902649d}, abstractNote={Chlorins bearing a six-membered imide ring spanning positions 13-15, commonly referred to as purpurinimides, exhibit long-wavelength absorption yet have heretofore only been available via semisynthesis from naturally occurring chlorophylls. A concise route to synthetic chlorins, which bear a geminal dimethyl group in the pyrroline ring, has been extended to provide access to chlorin-13,15-dicarboximides. The new route entails (i) synthesis of a 13-bromochlorin, (ii) palladium-catalyzed carbamoylation at the 13-position, (iii) regioselective 15-bromination under acidic conditions, and (iv) one-flask palladium-mediated carbonylation and ring closure to form the imide. In some cases the ring closure reaction afforded the isomeric (and readily separable) chlorin-isoimide in addition to the chlorin-imide. The resulting chlorin-imides and chlorin-isoimides exhibit long-wavelength absorption (679-715 nm) and emission (683-720 nm) in the far-red and near-infrared spectral region. The absorption of the chlorin-(iso)imides fills the spectral window between that of analogous synthetic chlorins and 13(1)-oxophorbines (603-687 nm) and bacteriochlorins (707-792 nm). The synthetic versatility of the de novo route complements the existing semisynthetic route from chlorophylls and should enable fundamental spectroscopic studies and photochemical applications.}, number={5}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Ptaszek, Marcin and Lahaye, Dorothee and Krayer, Michael and Muthiah, Chinnasamy and Lindsey, Jonathan S.}, year={2010}, month={Mar}, pages={1659–1673} }
 @article{krayer_ptaszek_kim_meneely_fan_secor_lindsey_2010, title={Expanded Scope of Synthetic Bacteriochlorins via Improved Acid Catalysis Conditions and Diverse Dihydrodipyrrin-Acetals}, volume={75}, ISSN={["0022-3263"]}, DOI={10.1021/jo9025572}, abstractNote={Bacteriochlorins are attractive candidates for a wide variety of photochemical studies owing to their strong absorption in the near-infrared spectral region. The prior acid-catalysis conditions [BF(3) x O(Et)(2) in CH(3)CN at room temperature] for self-condensation of a dihydrodipyrrin-acetal (bearing a geminal dimethyl group in the pyrroline ring) typically afforded a mixture of three macrocycles: the expected 5-methoxybacteriochlorin (MeOBC-type), a 5-unsubstituted bacteriochlorin (HBC-type), and a free base B,D-tetradehydrocorrin (TDC-type). Here, a broad survey of >20 acids identified four promising acid catalysis conditions of which TMSOTf/2,6-di-tert-butylpyridine in CH(2)Cl(2) at room temperature was most attractive owing to formation of the 5-methoxybacteriochlorin as the sole macrocycle regardless of the pyrrolic substituents in the dihydrodipyrrin-acetal (electron-withdrawing, electron-donating, or no substituent). Eleven new dihydrodipyrrin-acetals were prepared following standard routes. Application of the new acid catalysis conditions has afforded diverse bacteriochlorins (e.g., bearing alkyl/ester, aryl/ester, diester, and no substituents) in a few days from commercially available starting materials. Consideration of the synthetic steps and yields for formation of the dihydrodipyrrin-acetal and bacteriochlorin underpins evaluation of synthetic plans for early installation of bacteriochlorin substituents via the dihydrodipyrrin-acetal versus late installation via derivatization of beta-bromobacteriochlorins. Treatment of the 5-methoxybacteriochlorins with NBS gave regioselective 15-bromination when no pyrrolic substituents were present or when each pyrrole contained two substituents; on the other hand, the presence of a beta-ethoxycarbonyl group caused loss of regioselectivity. The 15 new bacteriochlorins prepared herein exhibit a long-wavelength absorption band in the range 707-759 nm, providing tunable access to the near-infrared region. Taken together, this study expands the scope of available bacteriochlorins for fundamental studies and diverse applications.}, number={4}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Krayer, Michael and Ptaszek, Marcin and Kim, Han-Je and Meneely, Kelly R. and Fan, Dazhong and Secor, Kristen and Lindsey, Jonathan S.}, year={2010}, month={Feb}, pages={1016–1039} }
 @misc{lindsey_muthukumaran_m._huma_2009, title={Boron complexation strategy for use in manipulating 1-acyldipyrromethanes}, volume={7,595,407}, number={2009 Sep. 29}, author={Lindsey, J. S. and Muthukumaran, K. Ptaszek and M. and Huma, H. Z. S.}, year={2009} }
 @article{kee_diers_ptaszek_muthiah_fan_lindsey_bocian_holten_2009, title={Chlorin-Bacteriochlorin Energy-transfer Dyads as Prototypes for Near-infrared Molecular Imaging Probes: Controlling Charge-transfer and Fluorescence Properties in Polar Media}, volume={85}, ISSN={["1751-1097"]}, DOI={10.1111/j.1751-1097.2008.00532.x}, abstractNote={Abstract}, number={4}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, author={Kee, Hooi Ling and Diers, James R. and Ptaszek, Marcin and Muthiah, Chinnasamy and Fan, Dazhong and Lindsey, Jonathan S. and Bocian, David F. and Holten, Dewey}, year={2009}, pages={909–920} }
 @article{krayer_balasubramanian_ruzie_ptaszek_cramer_taniguchi_lindsey_2009, title={Refined syntheses of hydrodipyrrin precursors to chlorin and bacteriochlorin building blocks}, volume={13}, ISSN={["1099-1409"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70450189510&partnerID=MN8TOARS}, DOI={10.1142/S1088424609001406}, abstractNote={ Bromo-substituted hydrodipyrrins are valuable precursors to synthetic bromo-chlorins and bromo-bacteriochlorins, which in turn are versatile substrates for derivatization in pursuit of diverse molecular designs. 8-bromo-2,3-dihydro-1-(1,1-dimethoxymethyl)-3,3-dimethyldipyrrin (1) is a crucial precursor in the rational synthesis of the bacteriochlorin building block 3,13-dibromo-8,8,18,18-tetramethylbacteriochlorin ( H2BC-Br3Br13) . 8-bromo-2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin (2) is a crucial precursor in the rational synthesis of the analogous 3,13-disubstituted chlorin building block (e.g. H2C-Br3M10Br13 ). The routes to 1 and 2 share a common precursor, namely 4-bromo-2-(2-nitroethyl)-1-N-tosylpyrrole (6-Ts), which is derived from pyrrole-2-carboxaldehyde. The prior seven-step synthesis of 1 from pyrrole-2-carboxaldehyde has limited access to H2BC-Br3Br13 given the large excesses of materials, extensive reliance on column chromatography, and low overall yield (1.4%). Refined procedures for synthesis of the common precursor 6-Ts as well as 1 and 2 afford the advantages of (1) diminished consumption of solvents and reagents, (2) limited or no use of chlorinated solvents, (3) limited or no chromatography, and (4) improved yields of most steps. Streamlined procedures enable the final two or three transformations to be performed without purification of intermediates. The new procedures facilitate the expedient preparation of 1 and 2 at the multigram scale. }, number={10}, journal={JOURNAL OF PORPHYRINS AND PHTHALOCYANINES}, publisher={World Scientific Pub Co Pte Lt}, author={Krayer, Michael and Balasubramanian, Thiagarajan and Ruzie, Christian and Ptaszek, Marcin and Cramer, David L. and Taniguchi, Masahiko and Lindsey, Jonathan S.}, year={2009}, month={Oct}, pages={1098–1110} }
 @article{muthiah_lahaye_taniguchi_ptaszek_lindsey_2009, title={Regioselective Bromination Tactics in the de Novo Synthesis of Chlorophyll b Analogues}, volume={74}, ISSN={["0022-3263"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-66449131206&partnerID=MN8TOARS}, DOI={10.1021/jo9002954}, abstractNote={The ability to introduce substituents at designated sites about the perimeter of the chlorin or 13(1)-oxophorbine macrocycle is essential for fundamental studies related to chlorophylls. A chlorin is a dihydroporphyrin, whereas a 13(1)-oxophorbine is a chlorin containing an annulated oxopentano ring spanning positions 13 and 15. 13(1)-Oxophorbines bearing auxochromes at the 7-position of the macrocycle are valuable targets given their resemblance to chlorophyll a or b, which contains the 13(1)-oxophorbine skeleton and bears a 7-methyl or 7-formyl group, respectively. A rational route to 7-substituted 13(1)-oxophorbines was developed that relies on a new method for regioselective bromination. Under neutral conditions, a 13-acetyl-10-mesitylchlorin (FbC-M(10)A(13)) undergoes bromination (with 1 molar equiv of NBS in THF) both in ring B (7-position) and at the 15-position (42% versus 28% isolated yield), thereby thwarting installation of the isocyclic ring (ring E, spanning the 13-15 positions). Under acidic conditions (10% TFA in CH(2)Cl(2)), ring B is deactivated, and bromination occurs preferentially at the 15-position (87% yield). The capability for preferential 15-bromination is essential to install the isocyclic ring, after which bromination can be directed to the 7-position of ring B (neutral conditions, 86% yield). The ability to suppress bromination in ring B (under acidic media) has been exploited in syntheses of sparsely substituted analogues of chlorophyll b. The analogues contain a 7-substituent (acetyl, formyl, or TIPS-ethynyl), a 10-mesityl group, and the 18,18-dimethyl group as the only substituents in the 13(1)-oxophorbine skeleton. The three analogues exhibit absorption spectral features that closely resemble those of free base analogues of chlorophyll b. Taken together, the facile access to chlorins and 13(1)-oxophorbines bearing substituents at distinct sites should enable fundamental spectroscopic studies and diverse applications.}, number={9}, journal={JOURNAL OF ORGANIC CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Muthiah, Chinnasamy and Lahaye, Dorothee and Taniguchi, Masahiko and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2009}, month={May}, pages={3237–3247} }
 @article{lindsey_ptaszek_taniguchi_2009, title={Simple Formation of an Abiotic Porphyrinogen in Aqueous Solution}, volume={39}, ISSN={["1573-0875"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77949775456&partnerID=MN8TOARS}, DOI={10.1007/s11084-009-9168-3}, abstractNote={Porphyrins have long been proposed as key ingredients in the emergence of life yet plausible routes for forming their essential pyrrole precursor have heretofore not been identified. Here we show that the anaerobic reaction of δ-aminolevulinic acid (ALA, 1-5 mM) with the β-ketoester methyl 4-methoxyacetoacetate (2-40 mM) in water (pH5-7) at 70-100°C for >6 h affords the porphyrinogen, which upon chemical oxidation gives the corresponding porphyrin in overall yield of up to 10%. The key intermediate is the α-methoxymethyl-substituted pyrrole, which undergoes tetramerization and macrocycle formation under kinetic control. The resulting type-I porphyrin bears four propionic acid and four carbomethoxy groups, is distinct from porphyrins (e.g., uroporphyrin or coproporphyrin) derivable from ALA alone via the extant universal biosynthetic path to tetrapyrroles, and is photoactive upon assembly into cationic micelles in aqueous solution. The simple self-organization of eight acyclic molecules into a tetrapyrrole macrocycle, from which a porphyrin is derived that is photoactive in lipid assemblies, augurs well for the spontaneous origin of catalysts and pigments essential for prebiotic metabolism and proto-photosynthesis.}, number={6}, journal={ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES}, publisher={Springer Nature}, author={Lindsey, Jonathan S. and Ptaszek, Marcin and Taniguchi, Masahiko}, year={2009}, month={Dec}, pages={495–515} }
 @article{mass_ptaszek_taniguchi_diers_kee_bocian_holten_lindsey_2009, title={Synthesis and Photochemical Properties of 12-Substituted versus 13-Substituted Chlorins}, volume={74}, ISSN={["0022-3263"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-68049111576&partnerID=MN8TOARS}, DOI={10.1021/jo900706x}, abstractNote={Understanding the effects of substituents on natural photosynthetic pigments is essential for the rational design of artificial photosynthetic systems. The long-wavelength absorption of chlorins derives from a transition that encompasses rings A and C, which includes the 2,3- and 12,13-positions, respectively. Chlorophylls bear a 3-vinyl group and a 13-keto group, as well as a full complement of substituents at the other beta-pyrrole sites. Prior studies of sparsely substituted synthetic chlorins to probe the effects of substituents yielded 3,13-substituted chlorins that contain a geminal dimethyl group in the pyrroline ring (for stability) and a mesityl group at the 10-position. Attempts to prepare analogous chlorins lacking the 10-mesityl substituent encountered unexpected difficulties during construction of the Eastern half precursor (8,9-dibromo-1-formyldipyrromethane) to the 13-bromochlorin. Direct bromination of 1-formyldipyrromethane with 2 mol equiv of NBS at -78 degrees C led to an isomeric mixture of the desired 8,9-dibromodipyrromethane (minor) and the unexpected 7,9-dibromodipyrromethane (major). Hence, a new rational route was developed for the synthesis of 8,9-dibromo-1-formyldipyrromethane that entailed (i) InCl(3)-catalyzed condensation of 4-bromo-2-(hydroxymethyl)pyrrole and pyrrole to give the 8-bromodipyrromethane, (ii) 1-formylation, and (iii) 9-bromination. Two new substituted chlorins carrying auxochromes at the 3- and 13-positions were synthesized. The photophysical and redox properties of the 13-substituted chlorins were compared with those of isomeric 12-substituted chlorins, synthesized previously via a 7,9-dibromo-1-formyldipyrromethane. Such studies (static absorption and fluorescence spectroscopy, time-resolved fluorescence spectroscopy, electrochemistry of the zinc chelates, and density functional theoretical calculations) reveal only very slight differences between the isomeric 12- and 13-substituted chlorins.}, number={15}, journal={JOURNAL OF ORGANIC CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Mass, Olga and Ptaszek, Marcin and Taniguchi, Masahiko and Diers, James R. and Kee, Hooi Ling and Bocian, David F. and Holten, Dewey and Lindsey, Jonathan S.}, year={2009}, month={Aug}, pages={5276–5289} }
 @misc{lindsey_muthukumaran_ptaszek_huma_s._2008, title={Boron complexation strategy for use in manipulating 1-acyldipyrromethanes}, volume={7,317,108}, number={2008 Jan. 8}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Lindsey, J. S. and Muthukumaran, K. and Ptaszek, M. and Huma, H. Z. and S.}, year={2008} }
 @misc{lindsey_muthukumaran_ptaszek_huma_2008, title={Boron complexation strategy for use in manipulating 1-acyldipyrromethanes}, volume={7,423,160}, number={2008 Sep. 9}, author={Lindsey, J. S. and Muthukumaran, K. and Ptaszek, M. and Huma, H. Z. S.}, year={2008} }
 @article{kee_nothdurft_muthiah_diers_fan_ptaszek_bocian_lindsey_culver_holten_2008, title={Examination of chlorin-bacteriochlorin energy-transfer dyads as prototypes for near-infrared molecular imaging probes}, volume={84}, ISSN={["1751-1097"]}, DOI={10.1111/j.1751-1097.2008.00409.x}, abstractNote={Abstract}, number={5}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, author={Kee, Hooi Ling and Nothdurft, Ralph and Muthiah, Chinnasamy and Diers, James R. and Fan, Dazhong and Ptaszek, Marcin and Bocian, David F. and Lindsey, Jonathan S. and Culver, Joseph P. and Holten, Dewey}, year={2008}, pages={1061–1072} }
 @article{dogutan_ptaszek_lindsey_2008, title={Rational or statistical routes from 1-acyldipyrromethanes to meso-substituted porphyrins. Distinct patterns, multiple pyridyl substituents, and amphipathic architectures}, volume={73}, ISSN={["0022-3263"]}, DOI={10.1021/jo800588n}, abstractNote={New methodology is described for the synthesis of porphyrins bearing four (A 4, cis-A 2B 2, cis-ABC 2, trans-A 2B 2) or fewer (A, cis-AB, cis-A 2, trans-A 2) meso substituents. The method entails condensation of two 1-acyldipyrromethanes in the presence of a metal salt (MgBr 2, 3 mol equiv) and a noncoordinating base (DBU, 10 mol equiv) in a noncoordinating solvent (toluene) with heating (conventional or microwave irradiation) and exposure to air. The rational synthesis of trans-A 2B 2- or trans-A 2-porphyrins was achieved via condensation of two identical 1-acyldipyrromethanes. The statistical synthesis of various meso-substituted porphyrins was achieved via condensation of two nonidentical 1-acyldipyrromethanes. Both routes possess attractive features including (1) no scrambling, (2) good yield (up to 60%) at high concentration (100 mM) for the macrocycle-forming step, (3) reasonable scope (aryl, heteroaryl, alkyl, or no substituent), (4) short reaction time ( approximately 2 h) via microwave irradiation, (5) magnesium porphyrins as the products, which easily undergo demetalation, and (6) facile chromatographic purification. A key advantage of the statistical route is to obtain a cis-substituted porphyrin without the corresponding trans isomer. For example, reaction of an A/B-substituted 1-acyldipyrromethane and the fully unsubstituted 1-formyldipyrromethane gave the magnesium chelates of three porphyrins: the trans-A 2B 2-porphyrin, the "hybrid" cis-AB-porphyrin, and porphine (no trans-AB-porphyrin can form), which were readily demetalated and separated as the free base species. Altogether 26 1-acyldipyrromethanes and 26 target porphyrins have been prepared, including many with two different pyridyl substituents. One set of amphipathic porphyrins includes cis-A 2B 2- or cis-A 2BC-porphyrins wherein A = pentyl and B/C = pyridyl ( o-, m-, p-). Taken together, the rational and statistical routes enable facile conversion of readily available 1-acyldipyrromethanes to diverse porphyrins bearing 1-4 meso substituents for which access is limited via other methods.}, number={16}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Dogutan, Dilek Kiper and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2008}, month={Aug}, pages={6187–6201} }
 @article{muthiah_kee_diers_fan_ptaszek_bocian_holten_lindsey_2008, title={Synthesis and excited-state photodynamics of a chlorin-bacteriochlorin dyad-through-space versus through-bond energy transfer in tetrapyrrole arrays}, volume={84}, ISSN={["1751-1097"]}, DOI={10.1111/j.1751-1097.2007.00258.x}, abstractNote={Abstract}, number={3}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, author={Muthiah, Chinnasamy and Kee, Hooi Ling and Diers, James R. and Fan, Dazhong and Ptaszek, Marcin and Bocian, David F. and Holten, Dewey and Lindsey, Jonathan S.}, year={2008}, pages={786–801} }
 @misc{lindsey_muthukumaran_ptaszek_h._2007, title={Boron complexation strategy for use in manipulating 1-acyldipyrromethanes}, volume={7,282,582}, number={2007 Oct. 17}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Lindsey, J. S. and Muthukumaran, K. and Ptaszek, M. and H., Zaidi. S.}, year={2007} }
 @article{dogutan_ptaszek_lindsey_2007, title={Direct synthesis of magnesium porphine via 1-formyldipyrromethane}, volume={72}, ISSN={["0022-3263"]}, DOI={10.1021/jo070532z}, abstractNote={The reaction of 1-formyldipyrromethane (100 mM) in toluene at 115 degrees C containing DBU (10 mol equiv) and MgBr2 (3 mol equiv) in the presence of air affords the magnesium chelate Mg(II) porphine in 30-40% yield. The advantages of the new method include simplicity, high concentration, chromatography-free purification, gram-scale synthesis, and avoidance of the poorly soluble free base porphine. Mg(II) porphine exhibits good solubility in common organic solvents and is a valuable core scaffold for derivatization.}, number={13}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Dogutan, Dilek Kiper and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2007}, month={Jun}, pages={5008–5011} }
 @article{kee_kirmaier_tang_diers_muthiah_taniguchi_laha_ptaszek_lindsey_bocian_et al._2007, title={Effects of substituents on synthetic analogs of chlorophylls. Part 1: Synthesis, vibrational properties and excited-state decay characteristics}, volume={83}, ISSN={["1751-1097"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34548711333&partnerID=MN8TOARS}, DOI={10.1111/j.1751-1097.2007.00150.x}, abstractNote={Abstract}, number={5}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, author={Kee, Hooi Ling and Kirmaier, Christine and Tang, Quin and Diers, James R. and Muthiah, Chinnasamy and Taniguchi, Masahiko and Laha, Joydev K. and Ptaszek, Marcin and Lindsey, Jonathan S. and Bocian, David F. and et al.}, year={2007}, pages={1110–1124} }
 @article{kee_kirmaier_tang_diers_muthiah_taniguchi_laha_ptaszek_lindsey_bocian_et al._2007, title={Effects of substituents on synthetic analogs of chlorophylls. Part 2: Redox properties, optical spectra and electronic structure}, volume={83}, ISSN={["1751-1097"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34548759138&partnerID=MN8TOARS}, DOI={10.1111/j.1751-1097.2007.00151.x}, abstractNote={Abstract}, number={5}, journal={PHOTOCHEMISTRY AND PHOTOBIOLOGY}, publisher={Wiley}, author={Kee, Hooi Ling and Kirmaier, Christine and Tang, Gun and Diers, James R. and Muthiah, Chinnasamy and Taniguchi, Masahiko and Laha, Joydev K. and Ptaszek, Marcin and Lindsey, Jonathan S. and Bocian, David F. and et al.}, year={2007}, pages={1125–1143} }
 @misc{ptaszek_mcdowell_taniguchi_kim_lindsey_2007, title={Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. Part 1: Synthesis}, volume={63}, ISSN={["0040-4020"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33947635677&partnerID=MN8TOARS}, DOI={10.1016/j.tet.2007.02.038}, abstractNote={Five routes to stable chlorins bearing 0 or 1 meso substituents have been investigated, among which reaction of a 9-bromo-1-formyldipyrromethane and 2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin proved most effective. Application of this route afforded metallochlorins [Cu(II), Zn(II), and Pd(II)] including the chlorin lacking any β-pyrrole and meso substituents.}, number={18}, journal={TETRAHEDRON}, publisher={Elsevier BV}, author={Ptaszek, Marcin and McDowell, Brian E. and Taniguchi, Masahiko and Kim, Han-Je and Lindsey, Jonathan S.}, year={2007}, month={Apr}, pages={3826–3839} }
 @article{taniguchi_ptaszek_mcdowell_lindsey_2007, title={Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. Part 2: Derivatization}, volume={63}, ISSN={["0040-4020"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33947700461&partnerID=MN8TOARS}, DOI={10.1016/j.tet.2007.02.076}, abstractNote={Stable chlorins bearing few or no substituents have been subjected to a variety of reactions including demetalation, magnesium insertion, oxochlorin formation, and bromination followed by Suzuki coupling. The kinetics of deuteration also have been determined for two oxochlorins and a series of chlorins bearing 0, 1, 2, or 3 meso-aryl substituents.}, number={18}, journal={TETRAHEDRON}, publisher={Elsevier BV}, author={Taniguchi, Masahiko and Ptaszek, Marcin and McDowell, Brian E. and Lindsey, Jonathan S.}, year={2007}, month={Apr}, pages={3840–3849} }
 @article{taniguchi_ptaszek_mcdowell_boyle_lindsey_2007, title={Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. Part 3: Spectral and structural properties}, volume={63}, ISSN={["0040-4020"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33947694765&partnerID=MN8TOARS}, DOI={10.1016/j.tet.2007.02.040}, abstractNote={The availability of stable chlorins bearing few or no substituents has enabled a variety of fundamental studies. The studies described herein report absorption spectra of diverse chlorins, comparative NMR features of chlorins bearing 0–3 meso-aryl substituents, and X-ray structures of the fully unsubstituted chlorin and the oxochlorin.}, number={18}, journal={TETRAHEDRON}, publisher={Elsevier BV}, author={Taniguchi, Masahiko and Ptaszek, Marcin and McDowell, Brian E. and Boyle, Paul D. and Lindsey, Jonathan S.}, year={2007}, month={Apr}, pages={3850–3863} }
 @article{ptaszek_yao_savithri_boyle_lindsey_2007, title={Synthesis and structural properties of porphyrin analogues of bacteriochlorophyll c}, volume={63}, ISSN={["0040-4020"]}, DOI={10.1016/j.tet.2007.10.023}, abstractNote={The self-assembling photosynthetic pigment bacteriochlorophyll c contains α-hydroxyethyl and keto groups on opposite sides of the macrocycle. A porphyrin has been synthesized that contains a 3-hydroxymethyl group and a 15-ethoxycarbonyl group (ZnP2-OH). X-ray analysis of ZnP2-OH and the related porphyrin containing 5-hydroxymethyl and 15-ethoxycarbonyl groups (ZnP1-OH) in each case revealed infinite coordination polymers wherein the zinc porphyrins are bound by Zn–O coordination and are cofacially offset in a staircase architecture.}, number={51}, journal={TETRAHEDRON}, author={Ptaszek, Marcin and Yao, Zhen and Savithri, Dhanalekshmi and Boyle, Paul D. and Lindsey, Jonathan S.}, year={2007}, month={Dec}, pages={12629–12638} }
 @article{kim_dogutan_ptaszek_lindsey_2007, title={Synthesis of hydrodipyrrins tailored for reactivity at the 1- and 9-positions}, volume={63}, ISSN={["0040-4020"]}, DOI={10.1016/j.tet.2006.10.027}, abstractNote={A collection of 33 hydrodipyrrins (9 targets, 21 intermediates, and 3 byproducts) has been prepared. The hydrodipyrrins (dihydrodipyrrins, tetrahydrodipyrrins, and hexahydrodipyrrins) contain a pyrrole ring and a geminal-dimethyl substituted 1-pyrroline (or pyrrolidine) ring. The α-substituents on the pyrrole ring (H, Br, CHO) and pyrroline ring (H, CH3, CH(OR)2, OMe, SMe) provide different reactivity combinations (Nu−, E+) and 0, 1, or 2 carbon atoms (which can give rise to the bridging meso-carbons in hydroporphyrins). Straightforward access to various hydrodipyrrins should facilitate development of syntheses of diverse hydroporphyrins.}, number={1}, journal={TETRAHEDRON}, author={Kim, Han-Je and Dogutan, Dilek Kiper and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2007}, month={Jan}, pages={37–55} }
 @article{yao_bhaumik_dhanalekshmi_ptaszek_rodriguez_lindsey_2007, title={Synthesis of porphyrins bearing 1-4 hydroxymethyl groups and other one-carbon oxygenic substituents in distinct patterns}, volume={63}, ISSN={["0040-4020"]}, DOI={10.1016/j.tet.2007.07.108}, abstractNote={Porphyrins that bear one-carbon oxygenic substituents (hydroxymethyl, formyl, ester) directly attached to the macrocycle afford a compact architecture that is attractive for diverse applications. Routes to 9 porphyrins bearing such groups in distinct architectures (A(4)-, trans-A(2)-, trans-A(2)B(2)-, trans-AB- and trans-AB(2)C-porphyrins) have been explored (A = hydroxymethyl), including porphyrins bearing two one-carbon units in different oxidation states (hydroxymethyl/ester, formyl/ester). The hydroxymethyl group was introduced via TBDMS-protected dipyrromethane precursors.}, number={43}, journal={TETRAHEDRON}, author={Yao, Zhen and Bhaumik, Jayeeta and Dhanalekshmi, Savithri and Ptaszek, Marcin and Rodriguez, Phillip A. and Lindsey, Jonathan S.}, year={2007}, month={Oct}, pages={10657–10670} }
 @article{muthiah_ptaszek_nguyen_flack_lindsey_2007, title={Two complementary routes to 7-substituted chlorins. Partial mimics of chlorophyll b}, volume={72}, ISSN={["1520-6904"]}, DOI={10.1021/jo701500d}, abstractNote={Chlorophyll a and chlorophyll b exhibit distinct spectra yet differ only in the nature of a single substituent (7-methyl versus 7-formyl, respectively). Two complementary approaches have been developed for the synthesis of 7-substituted chlorins. The first approach is a de novo route wherein 2,9-dibromo-5-p-tolyldipyrromethane (Eastern half) and 9-formyl-2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin (Western half) undergo acid-catalyzed condensation followed by metal-mediated oxidative cyclization. The resulting zinc chlorin is sterically uncongested and bears (1) a geminal dimethyl group in the reduced, pyrroline ring, (2) a bromo substituent at the 7-position, and (3) a p-tolyl group at the 10-position. The second approach entails regioselective 7-bromination of a 10,15-diarylchlorin that lacks a substituent at the 5-position. In an extension of this latter approach, a 5,15-diarylchlorin that lacks a substituent at the 10-position undergoes regioselective bromination at the 8-position. The introduction of a TIPS-ethynyl, acetyl, or formyl group at the 7-position was achieved using Pd-catalyzed reactions with the corresponding 7-bromochlorin. In the 10-p-tolyl-substituted zinc chlorins, the series of substituents (7-TIPS-ethynyl, 7-acetyl, 7-formyl) progressively causes (1) a bathochromic shift in the absorption maximum of the B band (405 to 426 nm) and (2) a hypsochromic shift in the position of the Qy band (605 to 598 nm). The trends mirror those for chlorophyll b versus chlorophyll a but are of lesser magnitude. Taken together, the facile access to chlorins that bear auxochromes at the 7-position enables wavelength tunability and provides the foundation for fundamental spectroscopic studies.}, number={20}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Muthiah, Chinnasamy and Ptaszek, Marcin and Nguyen, Tien M. and Flack, Kyle M. and Lindsey, Jonathan S.}, year={2007}, month={Sep}, pages={7736–7749} }
 @misc{lindsey_muthukumaran_ptaszek_zaidi_2006, title={Boron complexation strategy for use in manipulating 1-acyldipyrromethanes}, volume={7,153,975}, number={2006 Dec. 26}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Lindsey, J. and Muthukumaran, K. and Ptaszek, M. and Zaidi, S. H.}, year={2006} }
 @article{ptaszek_mcdowell_lindsey_2006, title={Synthesis of 1-formyldipyrromethanes}, volume={71}, ISSN={["0022-3263"]}, DOI={10.1021/jo060119b}, abstractNote={1-Formyldipyrromethanes are versatile precursors to porphyrins and chlorins. Two methods of synthesis of 1-formyldipyrromethanes have been investigated: (1) Vilsmeier formylation followed by selective removal of the unwanted 1,9-diformyldipyrromethane by dialkyltin complexation and (2) reaction with mesitylmagnesium bromide (MesMgBr) followed by formylation with phenyl formate. The two approaches are complementary (acidic versus basic conditions; statistical versus selective formylation). The latter was found to be more efficient for the preparation of 1-formyldipyrromethanes.}, number={11}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Ptaszek, Marcin and McDowell, Brian E. and Lindsey, Jonathan S.}, year={2006}, month={May}, pages={4328–4331} }
 @article{laha_muthiah_taniguchi_mcdowell_ptaszek_lindsey_2006, title={Synthetic chlorins bearing auxochromes at the 3- and 13-positions}, volume={71}, ISSN={["0022-3263"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33646926396&partnerID=MN8TOARS}, DOI={10.1021/jo060208o}, abstractNote={Synthetic chlorins bearing diverse auxochromes at the 3- and 13-positions of the macrocycle are valuable targets given their resemblance to chlorophylls a and b, which bear 3-vinyl and 13-keto groups. A de novo route has been exploited to construct nine zinc chlorins bearing substituents at the 3- and 13-positions and two benchmark zinc chlorins lacking such substituents. The chlorins are sterically uncongested and bear (1) a geminal dimethyl group in the reduced pyrroline ring, (2) a H, an acetyl, a triisopropylsilylethynyl (TIPS-ethynyl), or a vinyl at the 3-position, (3) a H, an acetyl, or TIPS-ethynyl at the 13-position, and (4) a H or a mesityl at the 10-position. The synthesis of the 13-substituted chlorins relied on p-TsOH x H2O-catalyzed condensation of an 8,9-dibromo-1-formyldipyrromethane (eastern half) and 2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin (western half), followed by metal-mediated oxidative cyclization, affording the 13-bromochlorin. Similar use of a bromo- or TIPS-ethynyl-substituted western half provided access to 3-substituted chlorins. A 3-bromo, 13-bromo, or 3,13-dibromochlorin was further transformed by Pd-coupling to introduce the vinyl group (via tributylvinyltin), TIPS-ethynyl group (via TIPS-acetylene), or acetyl group (via tributyl(1-ethoxyvinyl)tin, followed by acidic hydrolysis). In the 10-mesityl-substituted zinc chlorins, the series of substituents, 3-vinyl, 13-TIPS-ethynyl, 3-TIPS-ethynyl, 13-acetyl, 3,13-bis(TIPS-ethynyl), 3-TIPS-ethynyl-13-acetyl, or 3,13-diacetyl, progressively causes (1) a redshift in the absorption maximum of the B band (405-436 nm) and the Q(y) band (606-662 nm), (2) a relative increase in the intensity of the Q(y) band (I(B)/I(Q) = 4.2-1.5), and (3) an increase in the fluorescence quantum yield phi(f) (0.059-0.29). The zinc chlorins bearing a 3-TIPS-ethynyl-13-acetyl or a 3,13-diacetyl group exhibit a number of spectral properties resembling those of chlorophyll a or its zinc analogue. Taken together, this study provides access to finely tuned chlorins for spectroscopic studies and diverse applications.}, number={11}, journal={JOURNAL OF ORGANIC CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Laha, Joydev K. and Muthiah, Chinnasamy and Taniguchi, Masahiko and McDowell, Brian E. and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2006}, month={May}, pages={4092–4102} }
 @article{ptaszek_bhaumik_kim_taniguchi_lindsey_2005, title={Refined synthesis of 2,3,4,5-tetrahydro-1,3,3-trimethyidipyrrin, a deceptively simple precursor to hydroporphyrins}, volume={9}, ISSN={["1520-586X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-26444474619&partnerID=MN8TOARS}, DOI={10.1021/op050087e}, abstractNote={2,3,4,5-Tetrahydro-1,3,3-trimethyldipyrrin (1) is a crucial building block in the rational synthesis of chlorins and oxochlorins. The prior 5-step synthesis of 1 from pyrrole-2-carboxaldehyde (2) employed relatively simple and well-known reactions yet suffered from several drawbacks, including limited scale (>/= 0.5 g of 1 per run). A streamlined preparation of 1 has been developed that entails four steps: (i) nitro-aldol condensation of 2 and nitromethane under neat conditions to give 2-(2-nitrovinyl)pyrrole (3), (ii) reduction of 3 with NaBH(4) to give 2-(2-nitroethyl)pyrrole (4), (iii) Michael addition of 4 with mesityl oxide under neat conditions or at high concentration to give gamma-nitrohexanonepyrrole 5, and (iv) reductive cyclization of 5 with zinc/ammonium formate to give 1. Several multistep transformations have been established, including the direct conversion of 2 --> 1. The advantages of the new procedures include (1) fewer steps, (2) avoidance of several problematic reagents, (3) diminished consumption of solvents and reagents, (4) lessened reliance on chromatography, and (5) scalability. The new procedures facilitate the preparation of 1 at the multigram scale.}, number={5}, journal={ORGANIC PROCESS RESEARCH & DEVELOPMENT}, publisher={American Chemical Society (ACS)}, author={Ptaszek, M and Bhaumik, J and Kim, HJ and Taniguchi, M and Lindsey, JS}, year={2005}, pages={651–659} }