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

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

Volume: 22 Issue: 19

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

Affiliation:

• Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111 Budapest, Muegyetem rkp. 3,Hungary

• Chemical Works of Gedeon Richter Plc., H-1103 Budapest, Gyomroi ut 19-21,Hungary

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

Abstract: 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).

Cite this article as:

Szabó Balázs, Faigl Ferenc*, Éles János*, Greiner István, A Novel One-pot Benzimidazole Ring Formation via a Continuous Flow Selective Reductive Cyclization Method, Current Organic Chemistry 2018; 22 (19) . https://dx.doi.org/10.2174/1385272822666180829100850