Polyethylene Glycol (PEG-400) as an Efficient and Recyclable Reaction Medium for the One-Pot Synthesis of N-Substituted Azepines under Catalyst-Free Conditions

Abstract

Polyethylene glycol (PEG) was found to be an inexpensive nontoxic and effective medium for the one-pot synthesis of N-substituted azepines under catalyst-free conditions in excellent yields. Environmental acceptability, low cost, high yields, and recyclability of the PEG are the important features of this protocol.

Key words

anilines - dialkylacetylene dicarboxylates - 2,5-dimethoxytetrahydrofuran - N-substituted azepines - polyethylene glycol - catalyst-free conditions

References and Notes

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10

General Procedure for the Synthesis of N-Substituted Azapins by Using PEG as a Reaction Medium
A mixture of the requisite aniline (1.0 mmol), dialkyl-acetylene dicarboxylate (1.0 mmol), and 2,5-dimethoxy-tetrahydrofuran (1.0 mmol) was taken in PEG (5 mL) and stirred at 60 ˚C for the appropriate time. After completion of the reaction, as monitored by TLC, the reaction mixture was poured into H₂O and extracted with EtOAc. The organic layer was removed under reduced pressure, and the crude product was purified by column chromatography. The recovered PEG could be reused for a number of cycles without significant loss of activity.