@article{tran_wang_matsumoto_liu_jing_nalaoh_nguyen_taniguchi_lindsey_2023, title={Bacteriochlorin syntheses - Status, problems, and exploration}, volume={8}, ISSN={["1099-1409"]}, url={https://doi.org/10.1142/S1088424623501171}, DOI={10.1142/S1088424623501171}, abstractNote={ Bacteriochlorins – Nature’s near-infrared (NIR) chromophores – are distinguished by an intense ([Formula: see text] ∼;105 M[Formula: see text]cm[Formula: see text] long-wavelength absorption band in the ∼;700–1000 nm. The development of routes to prepare synthetic, tailorable bacteriochlorins holds promise for multiple disciplines where NIR-light-promoted photoactivity is of interest. A de novo route to bacteriochlorins equipped with a stabilizing gem-dimethyl group in each pyrroline ring was discovered in 2003. Continued development in this arena over 20 years has led to additional routes as well as methods to install substituents at selected positions about the perimeter of the macrocycle. The present paper reports studies that highlight substantial limitations of existing synthetic routes, including stymied access to multi-bacteriochlorin arrays and the inability to install (in a rational way) distinct groups at opposite sides of the macrocycle. The origins of the limitations are traced to particular stages of the chemistry ranging from derivatizing pyrroles, creating pyrrolines, constructing and elaborating dihydrodipyrrins, coupling dihydrodipyrrins, and forming macrocycles. Through exploration of a dozen aspects of bacteriochlorin syntheses, 60 new compounds (and nine known compounds via improved syntheses) have been prepared and characterized; the data include 20 single-crystal X-ray diffraction analyses. The research taken together points to areas of focus to fulfill the promise of this fascinating class of compounds. }, journal={JOURNAL OF PORPHYRINS AND PHTHALOCYANINES}, author={Tran, Vy-Phuong and Wang, Pengzhi and Matsumoto, Nobuyuki and Liu, Sijia and Jing, Haoyu and Nalaoh, Phattananawee and Nguyen, Khiem Chau and Taniguchi, Masahiko and Lindsey, Jonathan S.}, year={2023}, month={Aug} }
 @article{nguyen_tran_wang_zhang_wu_taniguchi_lindsey_2023, title={Four Routes to 3-(3-Methoxy-1,3-dioxopropyl)pyrrole, a Core Motif of Rings C and E in Photosynthetic Tetrapyrroles}, volume={28}, ISSN={["1420-3049"]}, url={https://doi.org/10.3390/molecules28031323}, DOI={10.3390/molecules28031323}, abstractNote={The photosynthetic tetrapyrroles share a common structural feature comprised of a β-ketoester motif embedded in an exocyclic ring (ring E). As part of a total synthesis program aimed at preparing native structures and analogues, 3-(3-methoxy-1,3-dioxopropyl)pyrrole was sought. The pyrrole is a precursor to analogues of ring C and the external framework of ring E. Four routes were developed. Routes 1–3 entail a Pd-mediated coupling process of a 3-iodopyrrole with potassium methyl malonate, whereas route 4 relies on electrophilic substitution of TIPS-pyrrole with methyl malonyl chloride. Together, the four routes afford considerable latitude. A long-term objective is to gain the capacity to create chlorophylls and bacteriochlorophylls and analogues thereof by facile de novo means for diverse studies across the photosynthetic sciences.}, number={3}, journal={MOLECULES}, author={Nguyen, Khiem Chau and Tran, Anh Thu Nguyen and Wang, Pengzhi and Zhang, Shaofei and Wu, Zhiyuan and Taniguchi, Masahiko and Lindsey, Jonathan S.}, year={2023}, month={Feb} }
 @article{jing_liu_jiang_tran_rong_wang_lindsey_2022, title={Meso bromination and derivatization of synthetic bacteriochlorins}, volume={46}, ISSN={["1369-9261"]}, DOI={10.1039/d1nj05853c}, abstractNote={Twelve bacteriochlorin building blocks featuring meso-substitution have been prepared including a set with finely tuned long-wavelength absorption (725–757 nm) for studies in photonics.}, number={12}, journal={NEW JOURNAL OF CHEMISTRY}, author={Jing, Haoyu and Liu, Sijia and Jiang, Jianbing and Tran, Vy-Phuong and Rong, Jie and Wang, Pengzhi and Lindsey, Jonathan S.}, year={2022}, month={Mar}, pages={5556–5572} }
 @article{jing_wang_chen_jiang_vairaprakash_liu_rong_chen_nalaoh_lindsey_2022, title={Synthesis of bacteriochlorins bearing diverse beta-substituents}, volume={3}, ISSN={["1369-9261"]}, DOI={10.1039/d1nj05852e}, abstractNote={Eleven bacteriochlorins have been prepared for surface attachment, bioconjugation, water-solubilization, vibrational studies, and elaboration into multichromophore arrays.}, journal={NEW JOURNAL OF CHEMISTRY}, author={Jing, Haoyu and Wang, Pengzhi and Chen, Boyang and Jiang, Jianbing and Vairaprakash, Pothiappan and Liu, Sijia and Rong, Jie and Chen, Chih-Yuan and Nalaoh, Phattananawee and Lindsey, Jonathan S.}, year={2022}, month={Mar} }
 @article{nguyen_wang_lindsey_2021, title={Study of conditions for streamlined assembly of a model bacteriochlorophyll from two dihydrodipyrrin halves}, volume={45}, ISSN={["1369-9261"]}, url={http://dx.doi.org/10.1039/d0nj04855k}, DOI={10.1039/d0nj04855k}, abstractNote={Knoevenagel condensation followed by double-ring closure (Nazarov cyclization, electrophilic aromatic substitution, elimination of methanol) and optional zinc insertion smoothly afford models of the native bacteriochlorophylls.}, number={2}, journal={NEW JOURNAL OF CHEMISTRY}, author={Nguyen, Khiem Chau and Wang, Pengzhi and Lindsey, Jonathan S.}, year={2021}, month={Jan}, pages={569–581} }
 @article{wang_lindsey_2021, title={Synthesis of AD-Dihydrodipyrrins Equipped with Latent Substituents of Native Chlorophylls and Bacteriochlorophylls}, volume={86}, ISSN={["1520-6904"]}, url={http://dx.doi.org/10.1021/acs.joc.1c01239}, DOI={10.1021/acs.joc.1c01239}, abstractNote={Native chlorophylls and bacteriochlorophylls share a common trans-substituted pyrroline ring D (17-propionic acid, 18-methyl), whereas diversity occurs in ring A particularly at the 3-position. Two dihydrodipyrrins equipped with native-like D-ring substituents and tailorable A-ring substituents have been synthesized. The synthesis relies on a Schreiber-modified Nicholas reaction to construct the stereochemically defined precursor to ring D, a dialkyl-substituted pent-4-ynoic acid. The carboxylic acid group of the intact propionic acid proved unworkable, whereupon protected propionate (-CO2tBu) and several latent propyl ethers were examined. The tert-butyldiphenylsilyl-protected propanol substituent proved satisfactory for reaction of the chiral N-acylated oxazolidinone, affording (2S,3S)-2-(3-((tert-butyldiphenylsilyl)oxy)propyl)-3-methylpent-4-ynoic acid in ∼30% yield over 8 steps. Two variants for ring A, 2-tert-butoxycarbonyl-3-Br/H-5-iodo-4-methylpyrrole, were prepared via the Barton-Zard route. Dihydrodipyrrin formation from the pyrrole and pentynoic acid entailed Jacobi Pd-mediated lactone formation, Petasis methenylation, and Paal-Knorr-type pyrroline formation. The two AD-dihydrodipyrrins bear the D-ring methyl and protected propanol groups with a stereochemical configuration identical to that of native (bacterio)chlorophylls, and a bromine or no substitution in ring A corresponding to the 3-position of (bacterio)chlorophylls. The analogous β-position of a lactone-pyrrole intermediate on the path to the dihydrodipyrrin also was successfully brominated, opening opportunities for late-stage diversification in the synthesis of (bacterio)chlorophylls.}, number={17}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Wang, Pengzhi and Lindsey, Jonathan S.}, year={2021}, month={Sep}, pages={11794–11811} }
 @article{chung_tran_chau nguyen_wang_lindsey_2021, title={Synthesis of model bacteriochlorophylls containing substituents of native rings A, C and E}, volume={7}, ISSN={["1369-9261"]}, url={http://dx.doi.org/10.1039/d1nj02469h}, DOI={10.1039/d1nj02469h}, abstractNote={An established route to the bacteriochlorophyll skeleton from two dihydrodipyrrin halves has been extended to accommodate several substituents characteristic of the native bacteriochlorophyll a.}, journal={NEW JOURNAL OF CHEMISTRY}, author={Chung, Duy T. M. and Tran, Phuong Vy and Chau Nguyen, Khiem and Wang, Pengzhi and Lindsey, Jonathan S.}, year={2021}, month={Jul} }
 @misc{wang_lindsey_2020, title={Riley Oxidation of Heterocyclic Intermediates on Paths to Hydroporphyrins-A Review}, volume={25}, ISSN={["1420-3049"]}, DOI={10.3390/molecules25081858}, abstractNote={Riley oxidation of advanced heterocyclic intermediates (dihydrodipyrrins and tetrahydrodipyrrins) is pivotal in routes to synthetic hydroporphyrins including chlorins, bacteriochlorins, and model (bacterio)chlorophylls. Such macrocycles find wide use in studies ranging from energy sciences to photomedicine. The key transformation (–CH3 → –CHO) is often inefficient, however, thereby crimping the synthesis of hydroporphyrins. The first part of the review summarizes 12 representative conditions for Riley oxidation across diverse (non-hydrodipyrrin) substrates. An interlude summarizes the proposed mechanisms and provides context concerning the nature of various selenium species other than SeO2. The second part of the review comprehensively reports the conditions and results upon Riley oxidation of 45 1-methyltetrahydrodipyrrins and 1-methyldihydrodipyrrins. A comparison of the results provides insights into the tolerable structural features for Riley oxidation of hydrodipyrrins. In general, Riley oxidation of dihydrodipyrrins has a broad scope toward substituents, but proceeds in only modest yield. Too few tetrahydrodipyrrins have been examined to draw conclusions concerning scope. New reaction conditions or approaches will be required to achieve high yields for this critical transformation in the synthesis of hydroporphyrins.}, number={8}, journal={MOLECULES}, author={Wang, Pengzhi and Lindsey, Jonathan S.}, year={2020}, month={Apr} }
 @article{wang_lu_lindsey_2020, title={Use of the Nascent Isocyclic Ring to Anchor Assembly of the Full Skeleton of Model Chlorophylls}, volume={85}, ISSN={["1520-6904"]}, DOI={10.1021/acs.joc.9b02770}, abstractNote={The chlorophyll skeleton contains a chlorin macrocycle and an annulated fifth (or isocyclic) ring bearing 131-oxo and 132-carbomethoxy substituents. The isocyclic ring has traditionally been constructed by annulation of an intact tetrapyrrole macrocycle. Here, a complementary route employs reaction of a gem-dimethyl-substituted dihydrodipyrrin-carboxaldehyde (AD half) and a dipyrromethane bearing a 3-methoxy-1,3-dioxopropyl group (BC half). A McMurry-like reaction of a 2-(2-nitro-5-oxohexyl)pyrrole was employed to construct the second pyrrole ring in one of three BC halves, whereas the other two were prepared by known routes. An AD half and a BC half were joined by Knoevenagel condensation at room temperature, affording the AD,BC-substituted 2-methoxycarbonyl-2-propenone. The subsequent reaction of three AD, BC-propenones (mixture of Z,E-isomers) in CH3CN containing InCl3 and In(OTf)3 at 80 °C afforded the chlorophyll skeleton as the chloroindium(III) chelate; the reaction proceeds via Nazarov cyclization (to form the isocyclic ring), SEAr (to construct the macrocycle), and 2e-,2H+ oxidation (to give the aromatic chromophore). The absorption spectra of the complexes closely resemble that of chlorophyll a. The present work exploits the nascent isocyclic ring as an anchor for directed assembly of the AD and BC halves, forming both the chlorin macrocycle and the isocyclic ring in a single-flask transformation.}, number={2}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Wang, Pengzhi and Lu, Futai and Lindsey, Jonathan S.}, year={2020}, month={Jan}, pages={702–715} }
 @article{wang_nguyen_lindsey_2019, title={Synthesis of the Ring C Pyrrole of Native Chlorophylls and Bacteriochlorophylls}, volume={84}, ISSN={["1520-6904"]}, DOI={10.1021/acs.joc.9b01650}, abstractNote={As part of a program to develop practical syntheses of members of the family of (bacterio)chlorophylls, two routes to 2-iodo-3-methyl-4-(3-methoxy-1,3-dioxopropyl)pyrrole, a precursor of the universal ring C, have been developed. The β-ketoester of ring C is expected to give rise to ring E upon Knoevenagel condensation and Nazarov cyclization with a ring D constituent as demonstrated in an analogue synthesis. Two viable routes were developed beginning with N-TIPS-pyrrole or with 4-oxo-2-pentene and TosMIC, affording multi-gram-quantities of this ostensibly simple pyrrole.}, number={17}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Wang, Pengzhi and Nguyen, Khiem Chau and Lindsey, Jonathan S.}, year={2019}, month={Sep}, pages={11286–11293} }