An expedient approach to tetrahydrofuro[3,2-b]pyridine-2(3H)-ones via activation of pyridine N-oxide by triflic anhydride

The double addition of bis(trimethylsilyl) ketene acetals [R1, R2 = CH3, –(CH2)5–] to pyridine N-oxide promoted by triflic anhydride under mild conditions generates N-[(trifluoromethane)sulfonyl-1,2-dihydropyridine-2,4-dicarboxylic acids 2a–b. Subsequent reaction of these acids upon iodolactonization conditions affords tetrahydrofuro[3,2-b]pyridine-2(3H)-ones 3a–b containing an exo-insaturation on the products as a result of an unexpected decarboxylation.