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Monday, February 19, 2018
Douglass F. Taber
University of Delaware

Enantioselective Construction of Alkylated Stereogenic Centers: The Nanda Synthesis of α-Cuparenone

Renata Marcia de Figueiredo and Jean-Marc Campagne of the Institut Charles Gerhardt Montpellier demonstrated (J. Org. Chem. 2017, 82, 4737. ) that the alcohol 1 could be hydrogenolyzed to 2 with retention of absolute configuration. Geum-Sook Hwang and Do Hyun Ryu of Sungkyunkwan University coupled (Angew. Chem. Int. Ed. 2017, 56, 3977. ) the α-diazo ester 3 with benzoic acid 4 to give the rearranged diester 5. Yong Huang of the Shenzen Graduate School of Peking University effected (J. Am. Chem. Soc. 2017, 139, 7045. ) enantioselective protonation of 6, leading via coupling with 7 to 8. Karl A. Scheidt of Northwestern University reported (J. Org. Chem. 2017, 82, 4689. ) related results. Tao Xiong of Northeast Normal University achieved (Org. Lett. 2017, 19, 3067. ) high enantioselectivity in the hydroboration of 9, leading to 10.

José Alemán of the Universidad Autónoma de Madrid assembled (J. Am. Chem. Soc. 2017, 139, 672. ) 13 by adding 12 in a conjugate sense to 11. Takanori Shibata of Waseda University ortho metalated (Chem. Eur. J. 2017, 23, 88. ) 14, then added the intermediate to 15, leading to 16. Jin-Quan Yu of Scripps/La Jolla converted (Science 2017, 355, 499. ) 17 to 18 by way of an enantioselectively metalated intermediate. Sarah E. Reisman of the California Institute of Technology attained (Org. Lett. 2017, 19, 2150. ) high enantioselectivity in the decarboxylative coupling of 19 with 20 to give 21.

Claudio Palomo of the Universidad del Pais Vasco constructed (Chem. Eur. J. 2017, 23, 8185. ) the quaternary center of 24 by adding 22 to 23. Stephen P. Fletcher of the University of Oxford showed (Chem. Sci. 2017, 8, 641. ) that the intermediate from hydrozirconation of 25 could be added to 26 in a conjugate fashion to give 27. Sanzhong Luo of the Institute of Chemistry of the Chinese Academy of Sciences effected (J. Am. Chem. Soc. 2017, 139, 3631. ) allylic coupling of 28 with the allene 29 to give 30. Bernhard Breit of the Albert-Ludwigs-Universität Freiburg described (Angew. Chem. Int. Ed. 2017, 56, 1903. ) a complementary allylic allene coupling (not illustrated). James M. Takacs of the University of Nebraska devised (J. Am. Chem. Soc. 2017, 139, 6066, ; Chem. Sci. 2017, 8, 4511, ) the enantioselective hydroboration of 31, leading via coupling to 32.

In another approach to alkylated quaternary centers, Samik Nanda of the Indian Institute of Technology Kharagpur rearranged (Tetrahedron 2017, 73, 809. ) the Sharpless-derived epoxide 33 to the aldehyde 34. Ring-closing metathesis of a later intermediate led to the sesquiterpene α-cuparenone (36).

D. F. Taber, Org. Chem. Highlights 2017, February 19.
URL: https://www.organic-chemistry.org/Highlights/2018/19February.shtm