Synthesisof 6H-Thieno(3,2-b)pyridin-7-onesfrom N-(2-X-Carbonyl)-3-thienyl Ketenimines (X = RS, ArO, R2N) via Consecutive (1,5)-X Sigmatropic Rearrangement and 6pi-Electrocyclization

摘要

N-(2-X-Carbonyl)-3-thienyl ketenimines (X = RS, ArO, R_2N) undergo cyclization under thermal conditions, through a [1,5]-X sigmatropic rearrangement followed by a 6 pi-electrocyclic ring closure of the resulting intermediate ketene, to provide 6H-thieno[3,2-b]pyridin-7-ones, bearing alkylthio, arylthio, aryloxy or amino groups at their 5-position