Affiliation:
1. N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk 630090, Russia
2. Novosibirsk State University, Pirogova str., 2, Novosibirsk 630090, Russia
Abstract
Background:
In recent years, microwave radiation has been widely used in organic synthesis, including solvent-free mode. However, the reaction conditions of phthalic anhydride with amino acids under solvent-free microwave activation have not been studied so far.
Objective:
In the present work, the effect of microwave activation on the interaction of phthalic anhy-dride with amino acids in solvent-free conditions has been studied in detail.
Methods:
The microwave heating dynamics of phthalic anhydride, glycine and their equimolar mixture under microwave conditions have been investigated, and the dependence of the heating rate on the mi-crowave power is defined.
Results:
The common conditions for the synthesis of phthaloylamino acids have been determined as continuous heating at a power of 200 W at 130 °C for 5-6 min and additional heating for 5-10 min at a temperature close to the melting point of the corresponding amino acid. We have applied the developed two-step solvent-free microwave reaction protocol successfully for the synthesis of phthaloyl deriva-tives of glycine, alanine, β-alanine, 4-aminobenzoic acid, γ-aminobutyric acid, isoleucine, leucine, phe-nylalanine.
Conclusion:
Reaction conditions for synthesizing phthaloylamino acids by microwave activation with-out solvent have been established. The solvent-free microwave reaction between phthalic anhydride and amino acid has been found to proceed in the melted phthalic anhydride.
Publisher
Bentham Science Publishers Ltd.