PPh3•HBr-DMSO: A Reagent System for Diverse Chemoselective Transformations

The broad applicability of the hitherto unexplored reagent combination PPh3 center dot HBr-DMSO is exemplified with multiple highly diverse one-step transformations to synthetically useful building blocks, such as flavones, 4H-thiochromen-4-ones, alpha-hydroxy ketones, 1,4-naphthoquinones (including vitamin K-3), 2-bromo-3-substituted-1H-1-indenones, 2-rnethylthio-1H-1-indenones, 3-butyne-1,2-dione, and 4-pentene-2,3-diones. The simple and mild reaction conditions make the reagent superior in terms of yield and substrate scope in comparison with the existing alternatives.