Bifunctionalized Allenes. VI. Synthesis of 3‐Sulfinylfuran‐2(5H)‐ones and 5H‐1,2‐Oxathiole‐3‐carboxylate 2‐Oxides by Bromination of 2‐Sulfinyl‐2,3‐alkadienoates

3‐Sulfinylfuran‐2(5H)‐ones 3 and 4 and 5H‐1,2‐oxathiole‐3‐carboxylate 2‐oxides 5 were synthesized in very good yields via electrophile‐induced cyclization reactions of 2‐sulfinyl‐2,3‐alkadienoates 1 and 2. Bromination of ethyl 2‐alkyl(phenyl)sulfinyl‐2,3‐alkadienoates 1 afforded 4‐bromo‐3‐alkyl(phenyl)sulfinylfuran‐2(5H)‐ones 3 only, while the reaction with ethyl 2‐alkoxysulfinyl‐2,3‐alkadienoates 2 led to formation of mixtures of 4‐bromo‐3‐alkyloxysulfinylfuran‐2(5H)‐ones 4 and 4‐bromo‐5H‐1,2‐oxathiole‐3‐carboxylates 2‐oxides 5.