Zur Oxidation von 1,2‐Thiazolen: Ein einfacher Zugang zu 1,2‐Thiazol‐3(2 H )‐on‐1,1‐dioxiden

Oxidation of 1,2‐Thiazoles; A Convenient Approach to 1,2‐Thiazol‐3(2 H )‐one 1,1‐Dioxides The 1,2‐thiazoles obtained from 3‐chloroalk‐2‐enals and ammonium thiocyanate ( 7 → 9 , Scheme 1 ) are easily transformed to 1,2‐thiazol‐3(2 H )‐one 1,1‐dioxidcs 10 on treatment with H 2 O 2 in AcOH at 80°. Hydrogenation of 10 in AcOH yields the corresponding saturated 1,2‐thiazolidin‐3‐one 1,1‐dioxides 16 ( Scheme 3 ). Cycloalka[ c ]‐1,2‐thiazoles 18 are prepared from 2‐[(thiocyanato)methyliden]cycloalkan‐1‐ones and ammonia ( Scheme 4 ). Surprisingly, oxidation of 18a with H 2 O 2 in AcOH yields the tricyclic oxaziridine 19.