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
摘要:
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.
Iminoisobenzofuran derivatives have been prepared in moderate yields by the palladium-catalyzed three-component coupling reaction of arynes, isocyanides, and cyanoformates. This paper is dedicated to Professor Ei-ichi Negishi on the occasion of his 77th birthday.
An efficient method for the direct conversion of cyano-substituted iminoisobenzofurans into their corresponding alkyl 2-cyanobenzoates has been developed. This transformation proceeds via cleavage of C-C, C-O, and C-N bonds in starting iminoisobenzofurans. DFT study revealed that intermediate a-iminonitriles are produced in situ via C-C bond formation between 2-iminium benzoates and a cyanide ion. Generation of isocyanide as the byproduct in a more thermodynamic manner in DFT calculations also supports the experimental results.
A NOVEL THREE-COMPONENT COUPLING REACTION OF ARYNES, ISOCYANIDES, AND CYANOFORMATES: A STRAIGHTFORWARD ACCESS TO CYANO-SUBSTITUTED IMINOISOBENZOFURANS
Iminoisobenzofuran derivatives have been prepared in moderate yields by the palladium-catalyzed three-component coupling reaction of arynes, isocyanides, and cyanoformates. This paper is dedicated to Professor Ei-ichi Negishi on the occasion of his 77th birthday.
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.