Showing posts with label Nitroanilines. Show all posts
Showing posts with label Nitroanilines. Show all posts

Wednesday, 25 January 2017

One-Pot Reductive Cyclisations of Nitroanilines to Imidazoles

Hana and co-workers ( Synlett 2010182759−2764) from Genentech have developed a single-step procedure for conversion of 2-nitro aromatic amines to benzimidazoles. Addition of ammonium chloride proved necessary as Fe powder and formic acid alone was ineffective for nitro reduction. These conditions were compatible with a variety of functional groups on the aromatic, including boronate esters. The methodology was also extended to nitro aminopyridines but failed to deliver the desired product with isoxazole or pyrazole reactants.

Mild and General One-Pot Reduction and Cyclization of Aromatic and Heteroaromatic 2-Nitroamines to Bicyclic 2H-Imidazoles

Emily J. Hanan*, Bryan K. Chan, Anthony A. Estrada, Daniel G. Shore, Joseph P. Lyssikatos

*Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA, Email:
E. J. Hanan, B. K. Chan, A. A. Estrada, D. G. Shore, J. P. Lyssikatos, Synlett2010, 2759-2764.

see article for more reactions
A one-pot procedure for the conversion of aromatic and heteroaromatic 2-nitroamines into bicyclic 2H-benzimidazoles employs formic acid, iron powder, and NH4Cl as additive to reduce the nitro group and effect the imidazole cyclization with high-yielding conversions generally within one to two hours. The compatibility with a wide range of functional groups demonstrates the general utility of this procedure.

see article for more examples
//////////One-Pot, Reductive Cyclisations,  Nitroanilines,  Imidazoles
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