Trifluoromethylated 2H‐Thiete, 2,3‐Dihydrothiophenes and 3,4‐Dihydro‐2H‐thiopyranes S,S‐Dioxides in [3+2]‐Cycloaddition Reactions with Diazo Compounds and Nitrilimines

Abstract

Abstract[3+2]‐Cycloaddition reactions of 3‐trifluoromethyl‐2H‐thiete 1,1‐dioxide, 4(5)‐trifluoromethyl‐2,3‐dihydrothiophene 1,1‐dioxides and 5(6)‐trifluoromethyl‐3,4‐dihydro‐2H‐thiopyrane 1,1‐dioxides with diazomethane proceed with the formation of regioisomeric mixtures of corresponding dihydropyrazole‐fused cycloadducts. Reactions of 3‐trifluoromethyl‐2H‐thiete 1,1‐dioxide with ethyl diazoacetate and in situ generated 2,2,2‐trifluorodiazoethane lead to the regioselective formation of pyrazolino‐sultine derivatives via rearrangement of initially formed pyrazoline‐fused thietane 1,1‐dioxides. Treatment of 3‐trifluoromethyl‐2H‐thiete 1,1‐dioxide and 4‐trifluoromethyl‐2,3‐dihydro‐thiophene 1,1‐dioxide with in situ generated N‐phenyl nitrilimines gives rise to dihydropyrazole‐ thietane 1,1‐dioxides and tetrahydrothiophene 1,1‐dioxides, respectively, in a regioselective fashion.