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.
Rh/(S)-(+)-DTBM-Segphos complexcatalyzedasymmetrichydrogenation of α-substituted vinyl sulfones has been achieved, furnishing the desired products in high yields and excellent enantioselectivities (>90% yield, up to 99% ee). This method provided an efficient approach to α-substituted chiral sulfones under mild conditions and has potential applications in organic synthesis.