Catalytic Asymmetric Synthesis of Dihydrofurans and Cyclopentenols with Tertiary Stereocenters

A new asymmetric synthesis of dihydrofurans and cyclopentenols has been developed and is based on the copper-catalyzed 1,2-addition of Grignard reagents to enones in combination with Sonogashira coupling/cyclization or ring-closing metathesis. By this approach, dihydrofurans with an oxygen-containing tertiary stereocenter and chiral tertiary cyclopentenols are efficiently prepared. The absolute stereochemistry of the products has been established.