Thermal cycloaddition reactions of thiocarbonyl compounds. Part 2. 1,3-dipolar cycloaddition reactions of adamantanethione with nitrile oxides, nitrilimines, and diazoalkanes

1,3-Dipolar cycloaddition of adamantanethione (1) with nitrile oxides, nitrilimines, and diazoalkanes occurred smoothly to afford regioselective cycloadducts, adamantane-2-spiro-5′-(1′4′,2′-oxathiazolines)(4a–f), adamantane-2-spiro-2′-(1′,3′,4′-thiadiazolines)(11a–d), and (21b), respectively in high yields. These results are discussed on the basis of FMO and steric effects.