CLEAVAGE OF MEM ETHERS BY TETRAHALOZINCATE REAGENTS

A modification of the zinc halide-mediated removal of the MEM group is described. By the expedient of adding two molar equivalents of ethere al hydrogen chloride or of lithium halide, the method is extended to s ubstrates which otherwise chelate the zinc reagent without undergoing deprotection. The compatibility of the resulting reagent systems with other functional groups is demonstrated, and examples are presented wh ere deprotection of mono-MEM-protected 1,2- and 1,3-diols can be carri ed out, avoiding the cyclisation which occurs normally. Copyright (C) 1996 Elsevier Science Ltd