Cycloadditions of adamantanethione S-methylide to CC multiple bonds

Adamantanethione S-methylide (12) is a nucleophilic I,3-dipole which easily combines with electrophilic acetylenic and ethylenic bonds affording dihyd rothiophene and thiolane derivatives, usually in high yields. The S-methyli de 12, generated by extrusion of nitrogen from the 2,5-dihydro-1,3,4-thiadi azole 11, can not be isolated, but is intercepted in situ by dipolarophiles ; otherwise, 12 furnishes irreversibly the spirothiirane 13. The H-1 nmr sp ectra and mass spectra establish the regiochemistry for the adducts of meth yl propiolate, acrylonitrile, methyl acrylate, benzylidenemalononitrile and methyl alpha-cyanacinnamate, The 1,3-dipole does not react with common alk enes; the highly strained trans-cyclooctene gives rise to a cycloadduct.