Highly Enantioselective [3+2] Annulation of Morita-Baylis-Hillman Adducts Mediated by L-Threonine-Derived Phosphines: Synthesis of 3-Spirocyclopentene-2-oxindoles having Two Contiguous Quaternary Centers
作者:Fangrui Zhong、Xiaoyu Han、Youqing Wang、Yixin Lu
DOI:10.1002/anie.201102094
日期:2011.8.16
Spiral bound: The Morita–Baylis–Hillmanadducts were employed as C3 synthons in the asymmetric [3+2] annulation with malonitrile substrates using L‐threonine‐derived 1 as the catalyst (see scheme). The reaction is highly regioselective and stereoselective, and affords optically enriched 3‐spirocyclopentene‐2‐oxindoles containing twocontiguousquaternarycenters. Boc=tert‐butoxycarbonyl, PMB=para‐methoxybenzyl