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Current Organic Chemistry


ISSN (Print): 1385-2728
ISSN (Online): 1875-5348

Research Article

A Novel One-pot Benzimidazole Ring Formation via a Continuous Flow Selective Reductive Cyclization Method

Author(s): Balázs Szabó, Ferenc Faigl*, János Éles* and István Greiner

Volume 22, Issue 19, 2018

Page: [1940 - 1944] Pages: 5

DOI: 10.2174/1385272822666180829100850

Price: $65


A novel, simple and efficient laboratory scale continuous flow protocol has been elaborated for one-pot benzimidazole synthesis via a reductive cyclization method using the commercially available H-Cube Pro. Coupling with a stainless steel microreactor (4mL reactor volume), the acylation of o-nitroaniline was successfully joined in the hydrogenation step without any isolation or purification steps. This concept enabled a fully integrated process using a standard 5% Pt/C, sulfide catalyst for the reductive cyclization of 2-nitroacetanilide with quantitative yield. Compared with the previously reported batch processes, the present procedure facilitated efficient synthesis of a broad range of benzimidazole derivatives bearing functionalities sensitive to reductive cleavage and acidic conditions (10 compounds, 82 to >99% selectivity).

Keywords: Benzimidazole, continuous flow, reductive cyclization, one-pot, selective synthesis, heterocycles

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