Metal-Mediated C-C Ring Construction: The Trost Synthesis of Conocenolide C

Xin Hong of Zhejiang University and Elizabeth R. Jarvo of the University of California, Irvine showed that the cyclization of 1 delivered the cyclopropane 2 with good diastereoselectivity (J. Am. Chem. Soc. 2020, 142, 5017. DOI: 10.1021/jacs.0c01330). Jianrong Steve Zhou of Peking University Shenzhen Graduate School achieved high ee in the cyclization of 3 to 4 (Angew. Chem. Int. Ed. 2020, 59, 10814. DOI: 10.1002/anie.202000859).

Rong Zhu of Peking University used the hypervalent iodine oxidant 6 in conjunction with a Co catalyst to effect the cyclization of 5 to 7 (ACS Catal. 2020, 10, 510. DOI: 10.1021/acscatal.9b04774). Cheol-Min Park of the Ulsan National Institute of Science & Technology observed the clean cyclization of 8 to 9 (Nature Commun. 2020, 11, 2509. DOI: 10.1038/s41467-020-16283-9). Jonathan W. Burton of the University of Oxford achieved high diastereoselectivity in the oxidative cyclization of 10 to 11 (Tetrahedron 2020, 76, 130981. DOI: 10.1016/j.tet.2020.130981). Israel Fernández and Jennifer M. Schomaker of the University of Wisconsin cyclized the ene allene 12 to the cyclopentane 13 (J. Am. Chem. Soc. 2020, 142, 5568. DOI: 10.1021/jacs.0c02441).

Lei Shi of the Harbin Institute of Technology devised a Rh catalyst that mediated the enantioselective formation of 16 by the addition of 15 to 14 (Org. Biomol. Chem. 2020, 18, 2956. DOI: 10.1039/D0OB00361A). Martin Rahm and Nina Kann of the Chalmers University of Technology and Simon E. Lewis of the University of Bath showed that 17, readily prepared by bio-oxidation of benzoic acid, could be coupled with 18 to give 19 (Org. Lett. 2020, 22, 2464. DOI: 10.1021/acs.orglett.0c00708). Ken Tanaka of the Tokyo University of Technology found that racemic 21 could be coupled with 20 to give 22 (Chem. Eur. J. 2020, 26, 3698. DOI: 10.1002/chem.202000010). Shunxi Dong and Xiaoming Feng of Sichuan University assembled 25 by combining 23 with 24 (Org. Lett. 2020, 22, 3551. DOI: 10.1021/acs.orglett.0c00984).

Wen-Bo Liu of Wuhan University cyclized the bis-nitrile 16 to the cycloheptenone 27 in high ee (J. Am. Chem. Soc. 2020, 142, 7328. DOI: 10.1021/jacs.0c02075). Christopher D. Vanderwal, also of the University of California, Irvine, used the oxidant 29 to promote the diastereoselective Co-catalyzed cyclization of 28 to 30 (Angew. Chem. Int. Ed. 2020, 59, 6115. DOI: 10.1002/anie.202000252).

Barry M. Trost of Stanford University devised a concise synthesis of conocenolide C (33), the key step of which was the diastereoselective Pd-catalyzed cyclization of 31 to 32. The reaction may involve participation by the free -OH, since cyclization of the corresponding silyl ether led to a 1.5:1 mixture of diastereomers (Nature Chem. 2020, 12, 568. DOI: 10.1038/s41557-020-0439-y).