Dual-Copper-Catalyzed Enantioselective Decarboxylative [2 + 3] Cycloaddition of Ethynyl Cyclic Carbamates/Carbonates with 4-Hydroxycoumarins.

A dual-copper-catalyzed enantioselective decarboxylative [2 + 3] cycloaddition of ethynyl cyclic carbamates/carbonates with 4-hydroxycoumarins and 4-hydroxyl pyrones was developed. This reaction provides an efficient method for accessing a wide range of optically pure dihydrofuro[3,2-c]coumarin derivatives in high yields with good to excellent enantioselectivities (61 examples, up to 99% yield and 99% ee). Notably, the ethynyl cyclic carbamates/carbonates were used as unconventional bis-electrophilic 2C (Cγ-Cβ) synthetic units for an enantioselective [2 + 3] cycloaddition reaction.