Aza-Michael Mono-addition Using Acidic Alumina under Solventless Conditions.

Giovanna Bosica,Roderick Abdilla

doi:10.3390/molecules21060815

Abstract

Aza-Michael reactions between primary aliphatic and aromatic amines and various Michael acceptors have been performed under environmentally-friendly solventless conditions using acidic alumina as a heterogeneous catalyst to selectively obtain the corresponding mono-adducts in high yields. Ethyl acrylate was the main acceptor used, although others such as acrylonitrile, methyl acrylate and acrylamide were also utilized successfully. Bi-functional amines also gave the mono-adducts in good to excellent yields. Such compounds can serve as intermediates for the synthesis of anti-cancer and antibiotic drugs.

Highlights

IntroductionFinaTllayboleth3.eYr icehldasllaenndgcionngdMitioicnhsafeolr macocneop-atacodcrdespitwtioorensr.oef mono-adduct which was supposedly formed could not tveasrtieodu.s aWmhineens wβ-itnhitdrioffsetryernetnMe iwchaaselused, the be characterized by 1H-NMR
FinaTllayboleth3.eYr icehldasllaenndgcionngdMitioicnhsafeolr macocneop-atacodcrdespitwtioorensr.oef mono-adduct which was supposedly formed could not tveasrtieodu.s aWmhineens wβ-itnhitdrioffsetryernetnMe iwchaaselused, the be characterized by 1H-NMR. This could be because the mono-RaddNHu2ct o+r the Michael acceptor itself were noRt stNabHle
The amine (7.5 mmol) and the Michael acceptor (5 mmol) in a molar ratio of 1.5:1 were refluxed with stirring in the presence of acidic alumina (1 g, 200 mol%)

Summary

Introduction

FinaTllayboleth3.eYr icehldasllaenndgcionngdMitioicnhsafeolr macocneop-atacodcrdespitwtioorensr.oef mono-adduct which was supposedly formed could not tveasrtieodu.s aWmhineens wβ-itnhitdrioffsetryernetnMe iwchaaselused, the be characterized by 1H-NMR This could be because the mono-RaddNHu2ct o+r the Michael acceptor itself were noRt stNabHle. it is reported that β-nitrostyrene undergoes [2 + 2] cycloaEdWdGition in the presence of sunlight [25]. The yields obtained for the additions of n-alkylamines to methyl methacrylate (12), methyl trans-crotonate (14) and methyl trans-cinnamate (16) were slightly less impressive, even if the reaction time was increased (entries 10–14). These observations can be explained in terms of steric reasons.

Procedure for Preparation of Mono-Adducts

Product Identification

Findings

Conclusions