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–Hillman adducts 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 two contiguous quaternary centers. Boc=tert‐butoxycarbonyl, PMB=para‐methoxybenzyl
螺旋键合:Morita–Baylis–Hillman加合物被用作C 3 合成子,在不对称[3 + 2]环化中以丙二腈为底物,使用L-苏氨酸衍生的1作为催化剂(参见方案)。该反应具有高度的区域选择性和立体选择性,并提供了包含两个连续四元中心的光学富集的3-螺环戊烯-2-氧吲哚。Boc =叔丁氧基羰基,PMB =对甲氧基苄基,TIPS =三异丙基甲硅烷基。