The stereochemistry of the Grignard — Ortho ester reaction revisited: Regioselective endocyclic cleavage in the reaction of Grignard reagents with cis-2-methoxy-4-methyl-1,3-dioxane
作者:William F. Bailey、Allan A. Croteau、Alberto D. Rivera
DOI:10.1016/s0040-4039(97)00862-9
日期:1997.6
The reaction of cis-2-methoxy-4-methyl-1,3-dioxane (4) with Grignard reagents proceeds in a totally regioselective manner via rupture of the less congested C(2)O(1) bond remote from the 4-methyl substituent. The analogous r-2-methoxy-cis-4,cis-6-dimethyl-1,3-dioxane (2) is totally inert to the action of Grignard reagents.
text]. Phenylalanine-derived B-aryl-N-tosyloxazaborolidinones selectively activate one of two enantiotopic oxygen atoms in prochiral anti dioxane acetals derived from meso-1,3-diols, leading to enantioselective formation of ring-cleavage products. The reaction is utilized as a key step in asymmetric desymmetrization of meso-1,3-diols.