Cycloadditions of Adamantanethione S-Methylide to CC Multiple Bonds

摘要

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