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Tuning the Reactivity of Isocyano Group: Synthesis of Imidazoles and Imidazoliums from Propargylamines and Isonitriles in the Presence of Multiple Catalysts
Author(s) -
Tong Shuo,
Wang Qian,
Wang MeiXiang,
Zhu Jieping
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201410113
Subject(s) - chemistry , catalysis , reactivity (psychology) , triple bond , amidine , metathesis , medicinal chemistry , carbene , racemization , propargyl , counterion , combinatorial chemistry , umpolung , amine gas treating , organic chemistry , double bond , nucleophile , polymerization , medicine , ion , alternative medicine , pathology , polymer
The reaction of propargyl amines with tert‐butylisonitrile in the presence of a catalytic amount of both Yb(OTf) 3 and AgOTf afforded imidazoles, whereas the same reaction with primary and secondary alkylisonitriles, as well as arylisonitriles, in the presence of three metal salts [Yb(OTf) 3 /AgOTf/KOTf] resulted in the 1,3,4,5‐tetrasubstituted imidazoliums in excellent yields. Both chiral amines and chiral isonitriles can be used to provide corresponding chiral heterocycles without racemization. In this multiple catalytic system, Yb(OTf) 3 catalyzed the insertion of isonitriles to the NH bond of amines, AgOTf catalyzed the 5‐exo‐dig cyclization of the resulting amidine nitrogen to the tethered triple bond, and KOTf promoted the salt metathesis, thus providing at the same time the counterion to the imidazolium. Against common knowledge, the isocyano group acted in these reactions as a polarized triple bond instead of conventional carbene‐like function.