Highly Diastereoselective Synthesis and Application of Functionalized 2,3-Dihydrofuran Derivatives from Enynones and Bis(diazo) Compounds

A highly efficient Ag(I)-catalyzed cascade Michael addition/cyclization of enynones with 1,3-(bis)diazo compounds has been established, providing functionalized 2,3-dihydrofuran derivatives containing a diazo group and an acetylenic bond with excellent diastereoselectivity. Transformation of the diazo group and hydration of the carbon–carbon triple bond have been performed successfully in different reaction systems.