Furopyridines. XVII . Cyanation,chlorination and nitration of furo[3,2-b]pyridine N-oxide

The N-oxide 2 of furo[3,2-b]pyridine ( 1 ) was cyanated by the Reissert-Henze reaction with potassium cyanide and benzoyl chloride to give 5-cyano derivative 3 , which was converted to the carboxamide 4 , carboxylic acid 5 , ethyl ester 6 and ethyl imidate 8 . Chlorination of 2 with phosphorus oxychloride yielded 2-9a , 3- 9b , 5- 9c and 7-chloro derivative 9d . Reaction of 9d with sodium methoxide, pyrrolidine, N,N-dimethylformamide and ethyl cyanoacetate afforded 7-methoxy- 10 , 7-(1-pyrrolidyl)- 11 and 7-dimethylaminofuro[3,2-b]pyridine ( 14 ) and 7-(1-cyano-1-ethoxy-carbonyl)methylene-4,7-dihydrofuro[3,2-b]pyridine ( 12 ). Nitration of 2 with a mixture of fuming nitric acid and sulfuric acid gave 2-nitrofuro[3,2-b]pyridine N-oxide ( 15 ).