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
Organometallic reactions in aqueous media. Indium-mediated allylation of sulfonimines
作者:Tak Hang Chan、Wenshuo Lu
DOI:10.1016/s0040-4039(98)01926-1
日期:1998.11
Barbier-type allylation of sulfonimines with indium and allyl bromide to give homoallylic sulfonamides can be performed smoothly in organic solvents and in aqueousmedia. The regio- and the stereoselectivity of the reaction have been examined.
A catalytic system, Pd(OAC)(2)(10 mol %)-P(n-Bu)(3) (20 mol %)-Et3B (360 mol %), promotes allylic alcohols to undergo the allylation of anisidine-imines of aromatic and aliphatic aldehydes and furnishes homoallylamines in good to moderate yields. The reaction shows unique stereoselectivity, giving ant isomers selectively.