Asymmetric aza-[2,3]-Wittig sigmatropic rearrangements: chiral auxiliary control and formal asymmetric synthesis of (2S, 3R, 4R)-4-hydroxy-3-methylproline and (–)-kainic acid
作者:James C. Anderson、Julian M. A. O'Loughlin、James A. Tornos
DOI:10.1039/b506198a
日期:——
stereochemistry of aza-[2,3]-Wittig sigmatropicrearrangements with diastereoselectivities of ca. 3 : 1 with respect to the auxiliary. In two specific examples, ca. 50% yields of enantiomerically pure products were obtained after chromatographic purification. These were synthetically manipulated with no erosion of stereochemistry into intermediates that completed formal asymmetric syntheses of (+)-HyMePro
Diastereoselective synthesis of substituted prolines via 5-endo-trig cyclisations of aza-[2,3]-Wittig sigmatropic rearrangement products
作者:James C. Anderson、Elizabeth A. Davies
DOI:10.1016/j.tet.2010.04.095
日期:2010.8
3]-Wittig sigmatropic rearrangement products from α-aminoacidderivatives are susceptible to a rare nucleophilic 5-endo-trigcyclisations of an amine onto a non-conjugated vinylsilane in high yield and complete diastereocontrol. Five examples are presented, with cyclisation yields between 35 and 87%. A rationale for the stereoselectivity of the cyclisation is forwarded based upon the steric control factors