p-Toluenesulfonylmethyl Isocyanide Derivatives Effective in the Construction of Heterocyclic Compounds

An isocyano group is used as a highly reactive functional group in organosynthetic reactions and many applications of its derivatives to multicomponent reactions have been reported. Other derivatives, which substitute a p-toluenesulfonylmethyl group directly to the isocyano group have an active methylene group so that they are effective for the use in the synthesis of heterocycles by multiple reactions regarding the active methylene group, promoted a condensation reaction as a key step. For example, an amine (2) and an aldehyde (3) form an imine and a subsequent van Leusen reaction proceeds by the treatment with α-(p-toluenesulfonyl)benzyl isocyanide (1) to afford a desired imidazole ring. Generally, isocyanide derivatives have a strong odor, but TosMIC and 1 are odorless solids, which have a remarkable feature of easier handling.