Copper(I)-Catalyzed Formal [4 + 2] Cyclocondensation of <i>ortho</i>-Hydroxybenzyl Alcohol, Aromatic Terminal Alkynes, and Sulfonyl Azides: An Alternative Approach to 2-Sulfonyliminocoumarins

Abstract

In this paper, an alternative and efficient copper(I)-catalyzed synthesis of 2-sulfonyliminocoumarins is developed through a three-component reaction of ortho-hydroxybenzyl alcohol, alkynes, and p-toluenesulfonyl azide. The proposed route for access to the 2-iminocoumarin ring involves a [4 + 2] hetero-Diels-Alder reaction between ortho-quinone methide and ketenimine intermediates generated in situ.

Keywords

• alkyne
• copper-catalyzed
• <i>ortho</i>-hydroxybenzyl alcohol
• sulfonyliminocoumarins