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. ). 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. ).
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. ). Cheol-Min Park of the Ulsan National Institute of Science & Technology observed the clean cyclization of 8 to 9 (Nature Commun. 2020, 11, 2509. ). Jonathan W. Burton of the University of Oxford achieved high diastereoselectivity in the oxidative cyclization of 10 to 11 (Tetrahedron 2020, 76, 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. ).
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. ). 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. ). 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. ). Shunxi Dong and Xiaoming Feng of Sichuan University assembled 25 by combining 23 with 24 (Org. Lett. 2020, 22, 3551. ).
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. ). 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. ).
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. ).