Cycloadditions of adamantanethione S-methylide to heteromultiple bonds

Article abstract of DOI:10.1016/S0040-4020(99)00664-X

Adamantanethione S-methylide (5) is an easily accessible thiocarbonyl S- ylide. Generated by N₂ elimination from the cycloadduct of adamantanethione and diazomethane, the nucleophilic 1,3-dipole 5 reacts in situ with thiocarbonyl compounds furnishing 1,3-dithiolanes. 5 and carbon disulfide afford 1:1 and 2:1 cycloadducts. The structures are assessed by NMR spectra, a X-ray analysis, and C-S hydrogenolyses. The C=S group is an ambident electrophile; the ratios of regioisomeric adducts suggest that electronic effects favor the 4',5'-substituted 1,3-dithiolanes, whereas steric effects support the 2',4'-substituted systems. Electrophilic carbonyl compounds and 5 regiospecifically provide 2,4-disubstituted 1,3-oxathiolanes. Imines appear to be weak dipolarophiles vs. 5.