Stereoelectronic factors in the stereoselective epoxidation of glycals and 4-deoxypentenosides.

ABSTRACT: Glycals and 4-deoxypentenosides (4-DPs), unsaturated pyranosides with similar structures and reactivity profiles, can exhibit a high degree of stereoselectivity upon epoxidation with dimethyldioxirane (DMDO). In most cases, the glycals and their corresponding 4-DP isosteres share the same facioselectivity, implying that the pyran substituents are largely responsible for the stereodirecting effect. Fully substituted dihydropyrans are subject to a "majority rule", in which the epoxidation is directed toward the face opposite to two of the three groups. Removing one of the substituents has a variable effect on the epoxidation outcome, depending on its position and also on the relative stereochemistry of the remaining two groups. Overall, we observe that the greatest loss in facioselectivity f

SUBMITTER: Alberch L 

PROVIDER: S-EPMC3074037 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature