Stereoselectivity in the Ortho Ester Claisen Rearrangements of the E and Z Isomers of γ-(1,3-Dioxan-4-yl)allyl Alcohols

Article abstract of DOI:10.1021/jo00294a025

The E and Z isomers of (2R,4S,5R)-5-hydroxy-4-(3-hydroxy-1-propenyl)-2-methyl-1,3-dioxane (3Z and 3E), which were derived from 4,6-O-ethylidene-D-glucose (1), and their 5-O-tert-butyldimethylsilyl derivatives (5Z) and (5E) served as substrates for Claisen rearrangements with triethyl orthoacetate.The rearrangement employing 5Z proceeds with moderate to high levels of diastereoselectivity.The chemically determined stereochemical assignments of the newly introduced stereogenic centers in the rearrangement products reveal that the diastereomer with an R configuration isthe major rearrangement product.The results of the Claisen rearrangement of 5Z with triethyl orthopropionate are also described.