Elemental Sulfur Mediated Synthesis of Pyrrolo[1,2-a]quinoxalines from 1-(2-Nitroaryl)pyrroles

Abstract

Methods to afford pyrrolo[1,2-a]quinoxalines often require the use of prefunctionalized aniline precursors, transition metals, and/or harsh conditions. Herein we describe a simple coupling of 1-(2-nitroaryl)pyrroles and arylacetic acids, in the presence of elemental sulfur, to furnish the fused heterocycles in good yields. The conditions are compatible with many functionalities including ester, nitrile, halogen, and nitro groups. Use of benzyl alcohols and picoline coupling reagents was also attempted.

Key words

metal free - annulation - pyrrolo[1,2-a]quinoxalines - elemental sulfur - nitroarenes

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