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Monday, July 22, 2019
Douglass F. Taber
University of Delaware

Arrays of Stereogenic Centers: The Tu Synthesis of (-)-Chimonanthidine

Masazumi Tamura and Keiichi Tomishige of Tohoku University reduced the methyl glycoside 1 to the cyclic acetal 2 (Angew. Chem. Int. Ed. 2018, 57, 8058. DOI: 10.1002/anie.201803043). Ming Wah Wong and Yu Zhao of the National University of Singapore assembled 5 by opening the aziridine 3 with 4 (Org. Lett. 2018, 20, 5112. DOI: 10.1021/acs.orglett.8b01948). Chuan Wang of the University of Science and Technology of China (ACS Catal. 2018, 8, 9376. DOI: 10.1021/acscatal.8b02591) and Mark S. Taylor of the University of Toronto (Org. Lett. 2018, 20, 5375. DOI: 10.1021/acs.orglett.8b02295) nearly simultaneously described the areneboronic acid-mediated regioselective opening of 6 with 7. Geoffrey W. Coates of Cornell University devised a catalyst-controlled protocol that enabled selective opening of an epoxide at the methyl-substituted end (Chem. Commun. 2018, 54, 12998. DOI: 10.1039/C8CC07200K). Yoshitaka Hamashima of the University of Shizuoka cyclized the prochiral 9 to the 2-oxazoline 10 in high ee (J. Org. Chem. 2018, 83, 7290. DOI: 10.1021/acs.joc.8b00039).

Mark A. Rizzacasa of the University of Melbourne combined 12 with the silylketene acetal derived from 11 to give the triester 13 after acid induced rearrangement of the cyclobutene intermediate (Org. Lett. 2018, 20, 4255. DOI: 10.1021/acs.orglett.8b01665). John C.-G. Zhao of the University of Texas at San Antonio devised a modular catalyst that mediated the Mannich alkylation of 14 with 15, leading to 16 (Tetrahedron 2018, 74, 6166. DOI: 10.1016/j.tet.2018.09.006). Matthew J. Gaunt of the University of Cambridge observed high diastereoselectivity in the cyclocarbonylation of 17 to the γ-lactam 18 (Chem. Sci. 2018, 9, 7628. DOI: 10.1039/C8SC02855A). Zhen-Ting Du of Northwest A&F University, Ju Hyun Kim of Gyeongsang National University and Sang-gi Lee of Ewha Womans University devised the coupling of 19 with 20 to give the β-lactam 21 (ACS Catal. 2018, 8, 7340. DOI: 10.1021/acscatal.8b01687).

Huw M. L. Davies of Emory University showed that the carbene derived from 23 could insert selectively into one of the ten C-H bonds of 22, leading to 24 (Org. Lett. 2018, 20, 3771. DOI: 10.1021/acs.orglett.8b01362). Yujiro Hayashi, also of Tohoku University, prepared 27 by adding 25 to 26 (Eur. J. Org. Chem. 2018, 6843. DOI: 10.1002/ejoc.201800831). Yonggui Robin Chi of Nanyang Technological University devised the coupling of 28 with 29 to give 30 (Chem. Sci. 2018, 9, 8711. DOI: 10.1039/C8SC03480J). James P. Morken of Boston College combined 31 with 32, leading to 33 (J. Am. Chem. Soc. 2018, 140, 15181. DOI: 10.1021/jacs.8b09909).

The alkaloid (-)-chimonanthidine (38) was isolated from the seeds of the Chinese flowering shrub Chimonanthus praecox. Yong-Qiang Tu of Lanzhou University and Shanghai Jiao Tong University assembled 37, having the adjacent quaternary centers of 38, by alkylating 34 with, sequentially, 35 and 36 (J. Am. Chem. Soc. 2018, 140, 10099. DOI: 10.1021/jacs.8b05386).

D. F. Taber, Org. Chem. Highlights 2019, July 22.