Asymmetric formal [1 + 2 + 2]-cycloaddition of diazoamides with enamines and carbonyl compounds.

Cycloaddition reaction offers an ideal and powerful method for the construction of cyclic structures with molecular complexity and diversity. The exploration of versatile synthons, especially in situ formed species, for the assembly of poly-functionalized heterocycles in one-pot is an intriguing and challenging area in synthetic chemistry from the perspective of atom economy and bond formation efficiency. Herein, we report an asymmetric formal [1 + 2 + 2]-cycloaddition of readily accessible diazoamides with enamines and carbonyl compounds. This cascade reaction involves a 1,3-dipolar cycloaddition of ketones/aldehydes with the key zwitterionic intermediate that generated in situ through an intermolecular metal carbene transfer to nucleophilic enamines, which offers a direct access to spiro-tetrahydrofurans containing four consecutive stereocenters in high yields and excellent enantioselectivity through chiral copper complex or chiral dirhodium carboxylates catalysis.