SYNTHESIS OF ISOTHIOCYANATOPHOSPHORANES AND ISOTHIOCYANATOPHOSPHONIUM SALTS VIA OXIDATIVE ADDITION OF THIOCYANOGEN AND LIGAND SUBSTITUTION. NOVEL REAGENTS FOR CONVERTING HYDROXY GROUPS INTO THIOCYANATE AND ISOTHIOCYANATE FUNCTIONS UNDER MILD CONDITIONS

Article abstract of DOI:10.1016/S0040-4020(01)88637-3

The oxidative addition of thiocyanogen to triphenilphosphine has been investigated by (31)P NMR spectroscopy showing the formation of the isothiocyanatophosphonium salt 8.The analogous reaction between thiocyanogen and alkyl o-phenylene phosphites 7 leads to diisothiocyanatophosphoranes 9.The same products were prepared via ligand substitution from the corresponding chlorophosphonium salt 12 and alkyldichloro-o-phenylene phosphoranes 13 by the action of potassium thiocyanate in the presence of 18-crown-6-ether or more conveniently using lead thiocyanate.The phosphonium salt 8 and phosphoranes 9 were employed as convenient novel reagents for converting hydroxy groups into thiocyanate and isothiocyanate function with high stereoselectivity under very mild conditions.The efficient synthesis of acylisothiocyanates RCONCS,R2P(O)NCS and R2P(S)NCS via addition of thiocyanogen to mixed anhydrides is of special interest.