Synthesis of N-alkoxybenzimidazoles with differentiated C2 and O-substituents
摘要:
N-Alkoxy-, N-aryloxy- and N-allyloxybenzimidazoles (prepared using tandem N-alkylation, heterocyclisation and O-alkylation with in situ alkylating agent) can be selectively O-deprotected and then independently realkylated to provide a protocol For diversification with differentiated substituents at C2 and on oxygen. In addition, carboxamide functionalised derivatives 8 are amenable to staged interruption of the tandem reaction, allowing sequential additions of two different bases and alkylating agents directly affording 9. This 'start-stop-start' tandem process also facilitates diversification to analogues bearing different C2 and N-alkoxy substituents. (C) 2001 Elsevier Science Ltd. All rights reserved.
Efficient One-Pot Conversion of 6-Methyl-2-nitroaniline into 1-Alkyloxy-2-alkyl-4-methyl-, 1-Benzyloxy-2-phenyl-4-Methyl-, and 1-Allyloxy-4-methyl-2-vinyl-benzimidazole
摘要:
6-Methyl-2-nitroaniline reacts with alkyl, benzyl and allyl halides and NaH as base, to afford 1-alkoxy-2-alkyl-, 1-benzyloxy-2-aryl- and 1-allyloxy-2-vinyl-benzimidazoles in good to excellent yields (73-98%), via a novel one-pot N-alkylation-heterocyclization-O-alkylation sequence.