ADDITION DE L'ACIDE THIOCYANIQUE AUX ACETYLENIQUES A L'AIDE DE Hg(II) II - OBTENTION D'ISOTHIOCYANATES VINYLIQUES PAR MERCURATION - PROTODEMERCURATION.

Article abstract of DOI:10.1016/S0040-4020(01)90604-0

Thiocyanic acid HSCN is added to some acetylenic compounds R¹-C<*>C-R² through a two step one-pot procedure which involves, first, the generation in CH2Cl2 of β-thiocyanato and/or β-isothiocyanato alkenyl mercuric compounds R¹-C(SCN)=CR²-Hg- by addition of mercury(II)thiocyanate Hg(SCN)2 to R¹-C<*>C-R², then the substitution of mercury by hydrogen through acidic treatment.In proper conditions of stoechiometry and reaction time the process is thermodynamically controlled and thus allows to obtain vinyl isothiocyanates R¹-C(-NCS)=CHR² even when the isomeric vinyl thiocyanates are kinetically favoured.Preparation of 3,3-dimethyl 2-isothiocyanato 1-thiocyanato 1-butene is also reported.