RESUMO
Highly enantioselective catalytic asymmetric reactions of rationally designed α-alkylidene ß-keto imides are described. The [4 + 2] cycloadditions and Hosomi-Sakurai reactions of α-alkylidene ß-keto imides proceed with high enantioselectivity and yield. The [4 + 2] cycloadditions of the imides with various dienes afford products bearing an all-carbon quaternary stereogenic center at the ring junction. α-Alkylidene ß-keto imides should be useful for the enantioselective total synthesis of natural products and other catalytic asymmetric applications.
RESUMO
The preparation of imides via the palladium-catalyzed coupling reaction as a one-carbon elongation reaction is described. The palladium-catalyzed coupling reaction of aryl-, alkyl-, and alkenylborons with N-[methoxy(methylthio)methylene]carbamate in the presence of Cu(I) thiophene-2-carboxylate (CuTC) affords imino ethers that are converted to the corresponding imides by acidic hydrolysis in high yield. The imino ethers are also useful for preparing the corresponding ester without using carbon monoxide.