Enantioselective Synthesis of Alcohols and Amines: The Yakura Synthesis of (+)-Tanikolide
John F. Hartwig of the University of California, Berkeley developed (J. Am. Chem. Soc. 2016, 138, 6703, DOI: 10.1021/jacs.6b02478; Angew. Chem. Int. Ed. 2016, 55, 776, DOI: 10.1002/anie.201509235) conditions for regioselective and enantioselective hydroboration, converting 1 to 2. The corresponding amines could also be prepared. Keiji Maruoka of Kyoto University devised (J. Am. Chem. Soc. 2016, 138, 5206. DOI: 10.1021/jacs.6b01462) a selenium catalyst that directed the cyclization of 3 to 4.
James P. Morken of Boston College assembled (Science 2016, 351, 70. DOI: 10.1126/science.aad6080) the alcohol 6 from the boronate 5 and vinyl lithium. Martin Breugst of the Universität zu Köln and Jörg Pietruszka of the Heinrich-Heine-Universität Düsseldorf added (Angew. Chem. Int. Ed. 2016, 55, 1548. DOI: 10.1002/anie.201509198) ethyl magnesium bromide to 7 to give an allyl boronate, that combined with benzaldehyde in pentane delivered the Z-alkene 8. Jian Zhou of East China Normal University established (J. Am. Chem. Soc. 2016, 138, 416. DOI: 10.1021/jacs.5b11476) conditions for the enantioselective formation of the cyanohydrin 10 from the ketone 9. Zhiyong Jiang of Henan University added (Org. Lett. 2016, 18, 260. DOI: 10.1021/acs.orglett.5b03412) the allyl ketone 12 to the α-keto ester 11 to give 13.
Hui Lv and Xumu Zhang of Wuhan University effected (Chem. Asian J. 2016, 11, 231. DOI: 10.1002/asia.201500892) the enantioselective hydrogenation of 14 to 15. Professor Zhang with Xinquan Hu of the Zhejiang University of Technology and Xiu-Qin Dong of Wuhan University were (Org. Lett. 2016, 18, 40. DOI: 10.1021/acs.orglett.5b03158) also successful with substrates such as 16. Mariafrancesca Fochi of the University of Bologna showed (Adv. Synth. Catal. 2016, 358, 1561. DOI: 10.1002/adsc.201600061) that reduction of 16 to 17 could also be carried out using a Hantzsch ester. Allenes such as 18 are readily prepared from terminal alkynes. Bernhard Breit of the Albert-Ludwigs-Universität Freiburg added (Chem. Sci. 2016, 7, 3313. DOI: 10.1039/C5SC04984A) the imine 19 to 18 to give, after hydrolysis and acylation, the amide 20. Shou-Fei Zhu and Qi-Lin Zhou of Nankai University used (Chem. Sci. 2016, 7, 1104. DOI: 10.1039/C5SC03558A) a Rh catalyst to mediate the insertion of the diazo ester 21 into the urethane to give α-amino acid derivative 22.
Tristan H. Lambert of Columbia University devised (Science 2016, 351, 961. DOI: 10.1126/science.aad0591) an organocatalyst that directed the addition of the ketene silyl acetal 24 to 23 to give 25. Yu Lan of Chongqing University and Yixin Lu of the National University of Singapore assembled (J. Am. Chem. Soc. 2016, 138, 265. DOI: 10.1021/jacs.5b10524) 28 by adding 26 to the allene ester 27.
Takayuki Yakura of the University of Toyama showed (Synlett 2016, 27, 1106. DOI: 10.1055/s-0035-1561341) that the sigmatropic rearrangement of the ylide derived from 29 proceeded with high diastereoselectivity to give 30. This translation of a secondary ether to a tertiary ether set the stage for the synthesis of (+)-tanikolide (31).