Abstract4‐Lithio‐N‐t‐butylpyridine‐3‐sulphonamide reacted with benzophenone and carbon dioxide respectively to give the corresponding intermediates which on appropriate treatment gave isothiazolo[5,4‐c]pyridin‐3‐one 1,1‐dioxides. Metalation of 2‐ and 4‐(N,N‐dialkylaminosulphonyl)pyridines with lithium diisopropylamide (LDA) gave anions which reacted with benzophenone to give carbinols which thermally cyclised to 1,2‐oxathiolo[3,4‐b]pyridine and 1,2‐oxathi