Novel iminium-type coupling agents containing proton acceptors in their iminium moiety, which can be used beneficially as coupling agents in various chemical polypeptide and/or polynucleotide syntheses, and are particularly useful as yield enhancing and racemization suppressing coupling agents for use in peptide syntheses, are disclosed. Further disclosed are a process of preparing such iminium-type coupling agents and their use in the preparation of polypeptides and/or polynucleotides.
Synthesis of 1-alkoxy-2-alkyl-benzimidazoles from 2-nitroanilines via tandem N-alkylation-cyclization-O-alkylation
作者:John M. Gardiner、Colin R. Loyns、Carl H. Schwalbe、Garry C. Barrett、Philip R. Lowe
DOI:10.1016/0040-4020(95)00127-t
日期:1995.4
Substituted 2-nitroanilines react with benzylic, allyl and alkyl halides to give 2-aryl-1-benzyloxy-, 1-allyloxy-2-vinyl- and 1-alkoxy-2-alkyl-benzimidazoles, in a one-pot cascade process involving 1-alkylation-cyclization-O-alkylation. 2-Aryl-1-benzyloxy- and 1-allyloxy-2-vinyl- derivatives are obtained in high yields (79-98%), while with simple alkyl halides, yields of the benzimidazoles are substrate dependent. An X-ray crystal structure of 2,4-dimethyl-1-ethoxybenzimidazole is presented.