Furopyridines. XXVI [1]. Reactions of cyanopyridine derivatives of furo[2,3-b]-, -[3,2-b]-, -[2,3-c]- and -[3,2-c]pyridine

Bromination of α-cyanopyridine derivatives of furopyridines 1a-d gave the 2,3-dibromo-2,3-dihydro compounds 2a-d in excellent yields. Treatment of 2a-d with sodium hydroxide in methanol yielded compounds formed through the dehydrobromination and solvolysis of the nitrile. N-Oxidation of 1a and 1b gave N-oxide in much poor yield, while 1c and 1d gave the N-oxide 13c and 13d in good yields. The nucleophilic reactions (cyanation, chlorination and acetoxylation) of 13c and 13d through a Reissert-Henze type reaction gave poor results, which would be caused by the strong electron withdrawing effect of the cyano group.