Efficient asymmetric synthesis of α-alkylated benzylic methyl sulfonates
摘要:
The first highly efficient auxiliary-controlled synthesis of various alpha-substituted sulfortic acid derivatives is described. Alkyl or aryl halides were reacted with lithiated benzylic sulfortic esters bearing 1,2:5,6-di-O-isopropylidene-alpha-D-allofuranose as a removable enantiopure alcohol auxiliary to give the alkylated products in excellent diastereomeric excesses. The racemization-free cleavage conditions provided highly enantioenriched sulfonic acid derivatives (ee >= 98%). (c) 2005 Elsevier Ltd. All rights reserved.
Asymmetric Synthesis ofα,γ-Substitutedγ-Sultones via Allylation of Chiral Lithiated Sulfonates
作者:Dieter Enders、Wacharee Harnying、Nicola Vignola
DOI:10.1002/ejoc.200300342
日期:2003.10
The first auxiliary controlled asymmetricsynthesis of enantiopure α,γ-substituted γ-sultones via α-allylation of lithiatedsulfonates by using 1,2:5,6-di-O-isopropylidene-α-D-allofuranose as chiral auxiliary is described. The high asymmetric inductions of the α-allylations were reached in good to excellent yields. Successive epimerization-free cleavage of the auxiliary and diastereoselective ring