Highly diastereoselective synthesis of cyclopropane-fused spiro-pseudoindoxyl derivatives through [2 + 1] annulation of 2-ylideneoxindoles and sulfonium bromides

Abstract

Compared with the intensively studied C3 spirooxindoles, limited reliable approaches are reported for synthesizing structurally analogous C2-spiropseudoindoxyl derivatives. Here, we developed an efficient method for highly diastereoselective synthesis of cyclopropane-fused spiropseudoindoxyl derivatives (up to 88% yield and >20 : 1 dr in all cases) through [2 + 1] annulation of (Z)-2-ylideneoxindoles with sulfur ylides.