Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University , 3663 North Zhongshan Road, Shanghai 200062, P. R. China.
Org Lett. 2017 Apr 7;19(7):1710-1713. doi: 10.1021/acs.orglett.7b00489. Epub 2017 Mar 22.
The development of electron-demand disfavored [4 + 2] cycloaddition of two electron-deficient reacting partners poses a considerable challenge. An enantioselective aza-[4 + 2] cycloaddition of electron-deficient N-sulfonyl-1-aza-1,3-dienes is possible with vinyl ketones via phosphine catalysis, which provides facile access to a wide range of enantioenriched trifluoromethylated tetrahydropyridines in up to 97% yield with 97% ee and >20:1 dr. The mechanistic study indicated that this cycloaddition proceeds via a tandem intermolecular aza-Rauhut-Currier/intramolecular aza-Michael addition reaction.
缺电子[4 + 2]环加成反应中两个缺电子反应试剂的发展提出了相当大的挑战。通过膦催化，缺电子的 N-磺酰基-1-氮杂-1,3-二烯与乙烯基酮可以进行对映选择性的氮杂[4 + 2]环加成反应，该反应为一系列的手性富集的三氟甲基化四氢吡啶提供了简便的方法，产率高达 97%，对映体过量值高达 97%，非对映选择性大于 20:1。机理研究表明，该环加成反应通过串联的分子间氮杂-Rauhut-Currier/分子内氮杂-Michael 加成反应进行。
