Stereoselective Synthesis of Tri- and Tetrasubstituted Olefins via 1,6-Additions of Diazo Compounds and Their Precursors to p‑Quinone Methides

Reactions of para-quinone methides (p-QMs) with α-diazo-β-ketosulfones and their corresponding esters as well as simple β-dicarbonyl compounds and β-ketosulfones have been carried out under basic conditions. While the reaction of diazosulfone with p-QMs afforded trisubstituted olefins via deacylative 1,6-addition and elimination, α-diazo-β-ketoesters and various active methylene compounds such as 1,3-dicarbonyls and β-ketosulfones afforded tetrasubstituted olefins via 1,6-addition and aerial oxidation. These simple, environmentally benign, and mechanistically diverse protocols provided the products in moderate to excellent yields and selectivities.