Catalyst- and Substrate-Dependent Chemodivergent Reactivity of Stabilised Sulfur Ylides with Salicylaldehydes

Stabilised sulfur ylides are synthetically appealing compounds, which reactivity under Brønsted acid catalysis has been poorly explored. Herein, we report a new catalyst- and substrate- dependent chemodivergent reaction between stabilised sulfur ylides and salicylaldehydes, leading to the (suprising) formation of 2H-chromenes or dihydrobenzofurans products. Particular attention was set on the unusual mechanisms involved. Two unique reaction routes including two ylide units in the reactions are proposed. These pathways were validated by performing a selectivity switch in some cases, enabled by the modulation of the nucleophilicity of the sulfur ylide, and by the loading of the Brønsted acid catalyst in the reaction.