Reaction of piperidine and morpholine with 2H‐pyran‐2‐ones, 2H‐thiopyran‐2‐ones, 2H‐pyran‐2‐thiones, and 2H‐thiopyran‐2‐thiones. A novel route to thiophene derivatives

Abstract

AbstractThe reaction of piperidine or morpholine with 2H‐pyran‐2‐ones was found to give open chain δ‐oxoamides, while with 2H‐thiopyran‐2‐ones, thiophene derivatives were formed. For 2H‐pyran‐2‐thiones, either open chain δ‐oxothioamides or thiophene derivatives were obtained. From the 1 H nmr data of the pyran derivatives, the effect of the replacement of ring and carbonyl oxygens with sulphur on the chemical shift of the H‐3 proton could be studied.