Furopyridines. XXVII. Reactions of 2-methyl and 2-cyano derivatives of furo[2,3-b]-, -[3,2-b]-, - [2,3-c]- and -[3,2-c]pyridine

Article abstract of DOI:10.1002/jhet.5570350601

Bromination of 2-methylfuropyridines 1a-d-Me gave the 3-bromo derivatives 2a-d, while the 2-cyano compounds 1a-d-CN resulted in the recovery of the starting compounds. Nitration of 1a-d-Me and 1a-d-CN did not yield the corresponding nitro derivative, except for 1-c-CN giving 3-nitro derivative 3c in 7% yield. N-Oxidation of 1a-d-Me and 1b-d-CN with m- chloroperbenzoic acid yielded the N-oxides 4a-d-Me and 4b-d-CN, whereas 1a- CN did not afford the N-oxide. Cyanation of N-oxides 4a-d-Me and 4b-d-CN with trimethylsilyl cyanide gave the corresponding α-cyanopyridine compounds 5a- d-Me and 5b-d-CN. Chlorination of 4a-d-Me and 4b-d-CN with phosphorus oxychloride also gave the α-chloropyridine compounds 6b-d-Me and 6b-d-CN, accompanying formation of γ-chloropyridine 6a-Me, 6'b-Me and 6'b-CN, β- chloropyridine 6(b)-CN, and α'-chloropyridine derivatives 6'c-Me and 6'c- CN. Acetoxylation of 4a-d-Me and 4b-d-CN with acetic anhydride yielded α- acetoxypyridine compounds 7a-Me and 7b-CN, pyridone compounds 11d-Me, 11c-CN and 11d-CN, 3-acetoxy compounds 8, 9b, 9c, and 2-acetoxymethyl derivatives 10b and 10c.