One-pot multicomponent nitro-Mannich reaction using a heterogeneous catalyst under solvent-free conditions.

Giovanna Bosica,Ramon Zammit

doi:10.7717/peerj.5065

Abstract

An environmentally-friendly, one-pot multicomponent reaction of various aldehydes, amines and nitroalkanes for the synthesis of β-nitroamines is here described. Amberlyst A-21 supported CuI was found to be a highly efficient novel heterogeneous catalyst for the three-component nitro-Mannich reaction between aldehydes, amines and nitroalkanes. The developed protocol is performed in a solvent-free medium to produce a variety of β-nitroamines in good to excellent yields within short reaction times. The catalyst can be easily prepared and recovered. It has been tested up to eight times with only a minor activity loss.

Highlights

The synthesis of bioactive secondary metabolites through the formation of networks of carbon–carbon bonds has fascinated synthetic organic chemists for entire generations (Kolb, Finn & Sharpless, 2001)
Several natural products and pharmaceuticals have been synthesised via an intermediate nitro-Mannich reaction including antiemetic (Tsuritani et al, 2002), analgesics (Kumaraswamy & Pitchaiah, How to cite this article Bosica and Zammit (2018), One-pot multicomponent nitro-Mannich reaction using a heterogeneous catalyst under solvent-free conditions
Various heterogeneous catalysts or catalytic species which could be immobilised on a solid support were all employed under solvent-free conditions

Summary

Introduction

The synthesis of bioactive secondary metabolites through the formation of networks of carbon–carbon bonds has fascinated synthetic organic chemists for entire generations (Kolb, Finn & Sharpless, 2001). In order to develop a greener approach to the nitro-Mannich reaction, efforts were made to employ Amberlyst A-21 supported CuI in a one-pot three-component strategy reaction between benzaldehyde (1a) and aniline (2a) (the starting materials required to form N -benzylideneaniline, 5) together with nitromethane (3a) (Fig. 4). The multicomponent reaction was performed in a sequential manner such that the catalyst, CuI-Amberlyst A-21, 1a and 2a were first mixed to form the intermediate 5 followed by addition of 3a in the same pot to form the resultant β-nitroamine 6.

Results

Conclusion