Reaction of sulfene with heterocyclic α‐dialkylaminomethyleneketones II. Synthesis of 5<i>N</i>‐1,2‐oxathiino[5,6‐<i>c</i>] [1]benzopyran derivatives

Abstract

Abstract The reaction of sulfene with 3‐dialkylaminomethylene‐4‐chromanone and 3‐dialkylamino‐methylene‐6‐methyl‐4‐ehromanone gave 1,4‐cycloadducts which are derivatives of a new heterocyclic system, i.e. , 5 H ‐1,2‐oxathiino[5,6‐ c ][1]benzopyran. The structures of the adductswere determined by ir and nmr spectral data. Two new α‐hydroxymethyleneketones (3‐hydroxy‐methylene‐4‐chromanone and its 6‐methyl analogue) as well as some of their derived enamines were prepared. During the preparation of N,N ‐diethylenamines a self‐condensation occurs, which gives the byproducts Xa‐b.