The additive-free 1,3-dipolar cycloaddition reaction of isatin-derived azomethine ylides with αcyano-α,β-unsaturated compounds was developed, which enabled diversity-oriented synthesis of a series of novel and structurally complex 3,3'-pyrrolidinyl-spirooxindoles derivatives containing four contiguous and two quaternary stereogenic centers in high yields (up to 92%) and excellent diastereoselectivities (up to > 25:1 dr). The reaction displays switchable regioselectivity depending on the steric effect of the substrates.

A simple and practical method for synthesizing a broad range of functionalized O-acylhydroxamates in high yields from oxime chlorides and carboxylic acids has been achieved.