New Entry to the Synthesis of α-Iminonitriles by Lewis Acid Mediated Isomerization of Cyano-Substituted Iminoisobenzofurans Prepared by Palladium-Catalyzed Three-Component Coupling of Arynes, Isocyanides, and Cyanoformates

A variety of alpha-iminonitriles were formed as the minor products of three-component coupling reactions of arynes, isocyanides, and cyanoformates in the presence of the cationic palladium complex [Pd(NCPh)(2)(dppf)1(BF4)(2) as the catalyst, along with cyano-substituted iminoisobenzofurans as the major products. alpha-Iminonitriles obtained from this process are hardly accessible by conventional methods. In addition, when the isolated iminoisobenzofurans were treated with diisobutylaluminum hydride (DIBAL-H) or AlMe3, the transformation of cyano-substituted iminoisobenzofurans into alpha-iminonitriles was observed.