Tetrahedron letters

Why are benzimidazoles efficiently acylated with esters? Identification of a tetrahedral hemiacetal alkoxide intermediate

…, C Kadowaki, S Karady, S Kii, K Maeda, BF Marcune…

Index: Asakawa, Ken-Ichi; Dannenberg; Fitch, Kenneth J.; Hall, Stan S.; Kadowaki, Chie; Karady, Sandor; Kii, Satoshi; Maeda, Kenji; Marcune, Benjamin F.; Mase, Toshiaki; Miller, Ross A.; Reamer, Robert A.; Tschaen, David M. Tetrahedron Letters, 2005 , vol. 46, # 30 p. 5081 - 5084

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Citation Number: 14

Abstract

Substituted benzimidazoles are important intermediates for the synthesis of various drugs and natural products. Substituents at the 2-position are generally introduced by reaction of the 2-lithio derivative of N-protected benzimidazoles with electrophiles. 1 The dimethoxymethyl N-protecting group has been used because of its easy removal and ketones were obtained by acylation of the corresponding carbanion. 2 In some cases when esters were used as acylating ...