Cerium Chloride (CeCl3·7H2O) as a highly efficient catalyst for one-pot Three-Component Mannich reaction

Mazaahir Kidwai,Jahan Anwar

doi:10.1590/s0103-50532010001200002

Abstract

We have demonstrated the use of CeCl3· 7H2O as highly efficient catalyst for one-pot Mannich reaction to afford β-amino carbonyl compounds in good to excellent yield within shorter period of reaction time. The process is mild, efficient, environmentally benign with the use of little amount of catalyst.

Highlights

Three-component reactions have emerged as a useful method, since the combination of three-components to generate new products in a single step is extremely economical, among the multi-component reaction.[1,2,3,4,5]Our research group focuses on finding efficient chemical transformation using three or more components in a single step by a catalytic process since it avoids use of stoichiometric toxic reagents, large amounts of solvents and expensive purification techniques which is the fundamental targets of modern organic synthesis.[6]There are many types of three-component reaction reported in the literature and Mannich reaction is one of the most important C-C bonds forming reaction
We have found CeCl37H2O as an efficient catalyst for the synthesis of β-amino carbonyl compounds at room temperature through a one-pot three-component reaction of aromatic aldehydes, ketones and aromatic amines in methanol (Scheme 1)
The intermediate II again activated by the catalyst through coordination by CeCl3 and the attack by enol to imine gives the desired product 4. Encouraged by these remarkable results, we screened a variety of aromatic aldehydes and amines having electron-withdrawing as well as electron-donating groups and in each case we observed good to excellent yields, when ortho-substituted anilines were used as substrates, the reaction gave no product probably due to steric hindrance of ortho-substituents

Summary

Introduction

Three-component reactions have emerged as a useful method, since the combination of three-components to generate new products in a single step is extremely economical, among the multi-component reaction.[1,2,3,4,5]Our research group focuses on finding efficient chemical transformation using three or more components in a single step by a catalytic process since it avoids use of stoichiometric toxic reagents, large amounts of solvents and expensive purification techniques which is the fundamental targets of modern organic synthesis.[6]There are many types of three-component reaction reported in the literature and Mannich reaction is one of the most important C-C bonds forming reaction. The conventional catalyst for the synthesis of β-amino carbonyl compounds of aldehydes, ketones and amines involve mainly organic and mineral acids like proline,[16,17,18] acetic acid,[19] p-dodecyl benzene sulfonic acid[20] and other Lewis acids.[21,22] They often suffer the drawbacks of long reaction times, harsh reaction conditions, toxicity and difficulty in product isolation. Soc. In this work, we have found CeCl37H2O as an efficient catalyst for the synthesis of β-amino carbonyl compounds at room temperature through a one-pot three-component reaction of aromatic aldehydes, ketones and aromatic amines in methanol (Scheme 1).

Results

Conclusion