Metal-Mediated C-C Ring Construction: The Harada/Nemoto Synthesis of Catharanthine
Fanke Meng of the Shanghai Institute of Organic Chemistry assembled the cyclopropane 3 by the enantioselective and diastereoselective addition of 2 to 1 (Angew. Chem. Int. Ed. 2019, 58, 11049. DOI: 10.1002/anie.201904994). T. V. RajanBabu of Ohio State University developed a Co catalyst for the enantioselective coupling of 4 with 5 to give the cyclobutene 6 (J. Am. Chem. Soc. 2019, 141, 15367. DOI: 10.1021/jacs.9b07885).
Jialin Wen and Xumu Zhang of the Southern University of Science and Technology achieved enzyme-like selectivity in the hydrogenation of 7 to 8 (Chem. Sci. 2019, 10, 6350. DOI: 10.1039/C9SC01769K). Hideki Abe of Japan Women's University and Hisanaka Ito of the Tokyo University of Pharmacy and Life Sciences cyclized 9 to 10 (Tetrahedron Lett. 2019, 60, 2059. DOI: 10.1016/j.tetlet.2019.06.058). Sylvain Darses of Chimie ParisTech prepared 13 by the addition of 12 to 11 (Org. Chem. Front. 2019, 6, 3978. DOI: 10.1039/C9QO01264H). Barry M. Trost of Stanford University used a Pd catalyst to combine 14 with 15, leading to 16 (Angew. Chem. Int. Ed. 2019, 58, 15154. DOI: 10.1002/anie.201910061).
Anita R. Maguire of University College Cork cyclized 17 to 18 in high ee (J. Org. Chem. 2019, 84, 7543. DOI: 10.1021/acs.joc.8b03160). Quan Cai of Fudan University prepared the protected arene dihydrodiol 21 by the addition of 20 to 19 (Angew. Chem. Int. Ed. 2019, 58, 14562. DOI: 10.1002/anie.201908284). Fernanda Duarte and Timothy J. Donohoe of the University of Oxford combined 22 with 23 to give 24 (Angew. Chem. Int. Ed. 2019, 58, 12558. DOI: 10.1002/anie.201907514). Jean-Marc Campagne of the Université Montpellier cyclized 25 to 26 (Org. Lett. 2019, 21, 10007. DOI: 10.1021/acs.orglett.9b03752).
Seiji Iwasa of the Toyohashi University of Technology prepared 28 by the cyclization of 27 (Chem. Commun. 2019, 55, 13398. DOI: 10.1039/C9CC06889A). Junichiro Yamaguchi of Waseda University described a related investigation (Org. Lett. 2019, 21, 10081. DOI: 10.1021/acs.orglett.9b04048). Bingfeng Sun, also of the Shanghai Institute of Organic Chemistry, converted 29 to 30 (Org. Lett. 2019, 21, 5082. DOI: 10.1021/acs.orglett.9b01678). While this was described as a Grob fragmentation, more accurately it is a Wharton fragmentation (J. Org. Chem. 1961, 26, 4781. DOI: 10.1021/jo01069a609).
The Vinca alkaloid catharanthine 33 can be coupled with vindoline to give vinblastine, a clinically-important anti-cancer agent. En route to 33, Shingo Harada and Tetsuhiro Nemoto of Chiba University cyclized racemic 31 to the corresponding meso diketone and reduced that to the diol 32, that could readily be desymmetrized (Org. Lett. 2019, 21, 3750. DOI: 10.1021/acs.orglett.9b01198).