Dimethyl Sulfoxide Provides Three Different Units in Synthesis of Chroman-4-ones Containing Sulfur and a Quaternary Carbon Center under HOAc Conditions.

HOAc-promoted construction of chroman-4-ones with a sulfur atom and an α-carbonyl quaternary carbon center directly from ortho -hydroxyacetophenones and DMSO is described. In these unique reactions, DMSO is activated by HOAc and provides three different units (CH 2 , CH 2 OH, and CH 2 SMe) in the target molecules. This reaction displays good substrate scope and reaction yields with a series of substitutes. The mechanism showed that the three units were formed in sequential order.