A novel one-pot and one-step microwave-assisted cyclization-methylation reaction of amino alcohols and acetylated derivatives with dimethyl carbonate and TBAC.

Adrián Ochoa-Terán,Ignacio A Rivero,Leticia Guerrero

doi:10.1155/2014/634935

Adrián Ochoa-Terán, Ignacio A Rivero + Show 1 more

Open Access

https://doi.org/10.1155/2014/634935

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Abstract

A simple and efficient microwave-assisted methodology for the synthesis of 4-substituted-3-methyl-1,3-oxazolidin-2-ones from amino alcohols catalyzed by a ionic liquid was developed. This novel one-pot and one-step cyclization-methylation reaction represents an easier and faster method than any other reported protocols that can be used to obtain the desired products in good yields and high purity. Applying microwave irradiation at 130°C in the presence of TBAC, dimethyl carbonate acts simultaneously as carbonylating and methylating agent and surprisingly promotes an in situ basic trans esterification when a N-acetylated amino alcohol is used as starting material. Furthermore, dimethyl carbonate worked better than diethyl carbonate in performing this reaction.

Highlights

Amino alcohols are readily available by reduction of an α-aminoacid and are important precursors in the synthesis of 1,3-oxazolidin-2-ones [1,2,3,4,5,6]
To the best of our knowledge, it has not been previously reported any studies to examine the use of TBAC as catalyst for the synthesis of N-alkyl-1,3-oxazolidin-2-ones from 1,2amino alcohols and mono and diacetylated amino alcohols and dialkyl carbonates
Our research group reported that dimethyl carbonate (DMC) acts as both carbonylating and alkylating agent in the synthesis of 1-alkyl

Summary

Introduction

Amino alcohols are readily available by reduction of an α-aminoacid and are important precursors in the synthesis of 1,3-oxazolidin-2-ones [1,2,3,4,5,6]. The preparation of 4-substituted-N-alkyloxazolidin-2-ones is achieved through a two steps sequence, that is, the carbonylation of 1,2-amino alcohols or N-acetylated amino alcohols with phosgene or triphosgene, followed by the N-alkylation of the resulting 1,3-oxazolidin-2-one with an alkyl halide (R2X) or a basic deacetylation and alkylation (Scheme 1). To the best of our knowledge, it has not been previously reported any studies to examine the use of TBAC as catalyst for the synthesis of N-alkyl-1,3-oxazolidin-2-ones from 1,2amino alcohols and mono and diacetylated amino alcohols and dialkyl carbonates. We report an efficient and novel synthesis of 4-substituted N-methyloxazolidin-2-ones where DMC acts as both carbonylating and alkylating agent in the presence of TBAC. This protocol exploits an unusual simultaneous cyclization-methylation using ionic liquids catalyst and microwave irradiation. Mono- and diacetylated amino alcohols are used in the cyclization-deacetylationmethylation process giving the desired products in excellent yields

Results and Discussion

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Conclusions

Experimental