[Omim][NO₃], a Green and Base-Free Medium for One-Pot Synthesis of Benzothiazinones at Room Temperature

Abstract

A general and efficient room-temperature procedure is developed for high-yield synthesis of 2H-benzo[b][1,4]thiazin-3(4H)-one derivatives in one pot from the reaction of 2-aminothiophenols with 2-bromoalkanoates in ionic liquid [bmim]NO₃ without the use of any catalyst, base, or additive. Products were obtained in good yields by simple extraction with Et₂O followed by evaporation of the volatile contents and recrystallization from Et₂O. The ionic liquid was recycled and reused in the next reaction without the loss of its activity.

GRAPHICAL ABSTRACT

Keywords:

• 1,4-Benzothiazin-3-ones
• green chemistry
• heterocyclization
• ionic liquids

ACKNOWLEDGMENT

The authors gratefully thank the Iran National Science Foundation (INSF) for financial support of this work (Project 88000118).

Notes

^a Isolated yields.

^a Isolated yields.

^a N-Methylpiperidine.