Direct and regioselective C-H alkenylation of tetrahydropyrido[1,2-a]pyrimidines.

The electrophilic C-H palladation and Heck-type alkenylation of the tetrahydro[1,2-a]pyrimidine scaffold leads to exclusive formation of the C(7) adducts, and this palladium-catalyzed process is applicable to a broad range of alkenyl components. Mechanistic studies suggest that palladation is selective for C(7), and there was no evidence for C(9) metalation; the latter corresponds to the pathway observed previously with N-methylpyridone.