Furopyridines .22. Elaboration of the C-substituents alpha to the heteronitrogen atom of furo[2,3-b]-, -[3,2-b]-, -[2,3-c]- and -[3,2-c]pyridine

The Grignard reaction of fused ring cyanopyridine derivatives 1a-d with methyl- and phenylmagnesium bromide yielded the corresponding acylpyridine compounds 2a-d and 3a-d. Furopyridine N-oxides 4a-d were converted into the compounds having a phenyl group at the alpha-position to the ring nitrogen 5a-d. Reduction of 1a-d and the carboxylic esters 6a-d with diisobutylaluminium hydride yielded the corresponding amines 7a-d and aldehydes 9a-d. The aldehydes were converted to nitroethanol derivatives 10a-d by condensation with nitromethane and acrylic ester compounds 11a-d by the Wittig-Horner reaction with methyl diethyl phosphonoacetate.