Metal-mediated Carbocyclic Construction: The Maimone Synthesis of Berkeleyone A
Elizabeth R. Jarvo of the University of California, Irvine cyclized (J. Am. Chem. Soc. 2016, 138, 14006. DOI: 10.1021/jacs.6b07567) the tetrahydropyran 1 to the alkenyl cyclopropane 2 with retention of absolute configuration at the oxygenated center and inversion at the halogenated center. Zuowei Xie of the Chinese University of Hong Kong and Yong Tang of the Shanghai Institute of Organic Chemistry assembled (J. Am. Chem. Soc. 2016, 138, 13151. DOI: 10.1021/jacs.6b08279) the cyclobutane 5 by adding 4 to 3.
Carlos Roque Duarte Correia of the State University of Campinas effected (Org. Biomol. Chem. 2016, 14, 9476. DOI: 10.1039/C6OB01892K) enantioselective Heck coupling of 7 with the prochiral 6 to give 8. Ullrich Jahn of the Czech Academy of Sciences acylated (Org. Biomol. Chem. 2016, 14, 9612. DOI: 10.1039/C6OB01599A) 9, then oxidized the resulting enolate, leading to cyclization to cyclopentane 10. Antonio A. Echavarren of ICIQ developed (Chem. Eur. J. 2016, 22, 13613. DOI: 10.1002/chem.201602347) a gold catalyst that cyclized 11 to 12. Michael P. Doyle of the University of Texas at San Antonio assembled (Angew. Chem. Int. Ed. 2016, 55, 10108. DOI: 10.1002/anie.201605438) the cyclopentene 15 by the Rh-catalyzed addition of 13 to 14.
Pher G. Andersson of Stockholm University showed (J. Am. Chem. Soc. 2016, 138, 11930. DOI: 10.1021/jacs.6b07291) that the inexpensive Birch reduction product 16 could be hydrogenated to 17 in high ee. E. J. Corey of Harvard University described (Org. Lett. 2016, 18, 6172. DOI: 10.1021/acs.orglett.6b03186) the enantioselective reduction of the prochiral dienone 18 to 19. Seth B. Herzon of Yale University devised (Org. Lett. 2016, 18, 4880. DOI: 10.1021/acs.orglett.6b02320) conditions for conjugate addition followed by acylation, converting cyclohexenone 20 to cyclohexanone 21. Zhi-Xiang Yu of Peking University achieved (J. Org. Chem. 2016, 81, 10165. DOI: 10.1021/acs.joc.6b01908) substantial enantioselectivity in the Heck coupling of 23 with 22, leading to 24.
Akio Kamimura of Yamaguchi University established (Tetrahedron Lett. 2016, 57, 3127. DOI: 10.1016/j.tetlet.2016.06.013) conditions for the oxidative cyclization of 25 to 26. En route to (-)-porosadienone (not illustrated), Ken Tanaka of the Tokyo Institute of Technology used (Angew. Chem. Int. Ed. 2016, 55, 15373. DOI: 10.1002/anie.201608952) a Rh catalyst to add 28 to the racemic β-keto ester 27, leading to 29 as an inconsequential mixture of diastereomers at the doubly acylated center.
Berkeleyone A (32), isolated from a strain of the fungus Penicillium rubrum growing in the Berkeley Pit, was found to have potent antiinflammatory activity. Thomas J. Maimone of the University of California, Berkeley assembled (J. Am. Chem. Soc. 2016, 138, 14868. DOI: 10.1021/jacs.6b10397) the tricyclic core 31 of 32 by the reductive cyclization of 30.