Electro-organic reactions part 35. Efficient carbon—oxygen bond formation in the anodic coupling of pyridopyrimidine derivatives.

Abstract

4-H-Pyrido[1,2-a]pyrimidine-2,4-diones (Chichibabin) derivatives, formed by condensation of 2-aminopyridines with substituted dialkylmalonates, are electroactive. In solution in CH 2Cl 2/CF 3CO 2H mixtures they are smoothly and selectively anodically coupled in high yield. The products are novel and unexpected; radical coupling at the C-3 and O-4 positions is involved and the proposed mechanism is analogous to that of oxidative phenolic coupling.