[82257-34-9] · C9H14N4O7S · 1,1´-Carbonylbis(3-imidazolium) Bis(methanesulfonate) · (MW 354.33)
(dehydrating agent capable of preparing isocyanides under acidic conditions2)
Preparative Method: freshly prepared by adding Methanesulfonic Acid to a solution of N,N´-Carbonyldiimidazole in acetonitrile.
The preparation of isocyanides from N-alkylformamides is typically accomplished with a dehydrating agent under basic conditions.1,3 The preparation of isocyanides using Trichloromethyl Chloroformate (diphosgene)4 and chlorodimethylforminium chloride5 (Vilsmeier reagent) has been reported. The title reagent was developed to prepare chiral isocyanides from chiral N-formyl amino acids, with minimal racemization (eq 1). The other, more basic, reaction conditions had proven unacceptable.
The reaction was carried out with freshly prepared carbonylbis(3-imidazolium) bis(methanesulfonate) in acetonitrile, at ambient temperature, over 4 h. Carbonyldiimidazole, without methanesulfonic acid, did not effect the transformation. Cyclohexyl isocyanide (85%), t-butyl isocyanide (85%), and methyl-L-2-isocyanoisovalerate (90%) were prepared to further demonstrate the reagent. Carbonylbis-(3-imidazolium) bis(methanesulfonate) failed to prepare 2-nitro-5-methoxyphenyl isocyanide from the corresponding N-formylanilide. Carbonylbis-(3-imidazolium) bis(methanesulfonate) is conveniently prepared from readily available starting materials and avoids the problems associated with handling Phosgene or phosgene equivalents.
Great Lakes Chemical Corporation, West Lafayette, IN, USA