Substituted Benzenes: The Guo/Ye Synthesis of Psymberin
Thilo J. Heckrodt of Rigel Pharmaceuticals optimized the N substituents of 1 such that bromination proceeded to give exclusively the 4-Br substituted 2 (Tetrahedron 2019, 75, 2385. DOI: 10.1016/j.tet.2019.02.059). Zhiguo Zhang and Guishen Zhang of Henan Normal University oxidized acetanilide 3 to 4 (J. Org. Chem. 2019, 84, 780. DOI: 10.1021/acs.joc.8b02636). Yoshiaki Nakao of Kyoto University assembled 7 by coupling 5 with 6 (Heterocycles 2019, 99, 1128. DOI: 10.3987/COM-18-S(F)84). Eiji Tayama of Niigata University rearranged 8 to the amide 9 (Tetrahedron 2019, 75, 665. DOI: 10.1016/j.tet.2018.12.058).
Dawei Ma of the Shanghai Institute of Organic Chemistry prepared the aryl ether 12 by coupling the alcohol 11 with 10 (J. Am. Chem. Soc. 2019, 141, 3541. DOI: 10.1021/jacs.8b12142). Kenichi Murai of Osaka University developed the oxidative rearrangement of 13 to 14 (Org. Lett. 2019, 21, 3023. DOI: 10.1021/acs.orglett.9b00559). Ning Jiao of Peking University reported related results (Nature Chem. 2019, 11, 71. DOI: 10.1038/s41557-018-0156-y).
Michal Szostak of Rutgers/Newark coupled 16 selectively with the tosylate of 15, leading to 17 (Adv. Synth. Catal. 2019, 361, 2329. DOI: 10.1002/adsc.201801586). Jon Loren of the Genomics Institute of the Novartis Research Foundation activated the carboxylate of 19 with PITU to enable electrochemical coupling with 18 to give 20 (Org. Lett. 2019, 21, 816. DOI: 10.1021/acs.orglett.8b04090). Phil S. Baran of Scripps/La Jolla reported a parallel investigation using α-quaternary carboxylates (Angew. Chem. Int. Ed. 2019, 58, 2454. DOI: 10.1002/anie.201814524).
Srivari Chandrasekhar of the Indian Institute of Chemical Technology described the Caubčre coupling of 21 with the benzyne derived from 22, leading to 23 (Org. Biomol. Chem. 2019, 17, 2192. DOI: 10.1039/C8OB03123A). Akkattu T. Biju of the Indian Institute of Science, Bangalore showed that the generation of the benzyne from 25 in the presence of KBr led to an anion that added to 24 to give the benzylic alcohol 26 (Org. Lett. 2019, 21, 4383. DOI: 10.1021/acs.orglett.9b01621). Sylvain Darses of Chimie ParisTech used a Rh catalyst to mediate both the addition of 28 to 27, and the subsequent ortho metalation and enantioselective cyclization to 29 (J. Org. Chem. 2019, 84, 4566. DOI: 10.1021/acs.joc.9b00442). Masahiro Toyota of Osaka Prefecture University effected the oxidative cyclization of 30 to 31 (Tetrahedron Lett. 2019, 60, 1653. DOI: 10.1016/j.tetlet.2019.05.041).
Psymberin (35) isolated by Crews from the marine sponge Psammocinia sp., was later shown to be identical with irciniastatin A, isolated at the same time by Pettit from the marine sponge Ircinia ramosa. En route to 35, Yian Guo and Tao Ye of the Peking University Shenzhen Graduate School constructed 34 by heating 33 with the highly functionalized 32 (Org. Lett. 2019, 21, 3670. DOI: 10.1021/acs.orglett.9b01113).