Synthesis and Structure of Spirocyclic Tetrahydrothiophene Derivatives Bearing a 'Cage' Residue

Trapping of the thiocarbonyl S-methanide 4 with tetracyanoethene and N-methylmaleimide led to the [3+2]-cycloadducts 11 and 12, respectively. The structures of these cycloadducts were established by X-ray crystallography. The 1,3-dipole 4 has been generated by thermal decomposition of the corresponding 2,5-dihydro-1,3,4-thiadiazole 2, which was prepared by the 1,3-dipolar cycloaddition of diazomethane with thioketone 1.