Concise synthesis of 3- C -glycosyl isocoumarins and 2-glycosyl-4 H -chromen-4-ones.

A new Ru-catalyzed C-H activation/cyclization reaction for the synthesis of 3- C -glycosyl isocoumarins and 2-glycosyl-4 H -chromen-4-ones with carbonyl sulfoxonium ylide glycogen are reported. In this catalytic system, benzoic acid and its derivatives react with carbonyl sulfoxonium ylide glycogen to yield isocoumarin C -glycosides, while 2-hydroxybenzaldehyde substrates react to produce chromone C -glycosides. These reactions were characterized by mild reaction conditions, broad substrate scope, high functional-group compatibility, and high stereoselectivity to yield several high-value isocoumarins and chromone skeleton-containing C -glycosides. The methods were successfully implemented in the context of large-scale reactions and the late-stage modification of complex natural products.