Catalyst-Controlled Divergent Synthesis of 2 H -Chromenes via [3 + 3] Annulation of Vinyl Sulfoxonium Ylides with Quinones.

Herein, we report the synthesis of 2 H -chromenes via catalyst-controlled highly regioselective [3 + 3] annulation of vinyl sulfoxonium ylides with quinones. Under boron-catalyzed conditions, the reaction between the ylide and quinone resulted in the formation of 2 H -chromene-4-carboxylates. In contrast, a different mechanistic pathway was observed when utilizing a Ru(II) catalytic system, which led to the formation of 2 H -chromene-2-carboxylates through a furan intermediate.