Synthesis of Tetrasubstituted Alkenes through a Palladium-Catalyzed Domino Carbopalladation/C-H-Activation Reaction

Helical tetrasubstituted alkenes (7) were obtained in a highly efficient way through a palladium-catalyzed domino-carbopalladation/CH-activation reaction of propargylic alcohols 6 in good to excellent yields. Electron-withdrawing- and electron-donating substituents can be introduced onto the upper and lower aromatic rings. The substrates (6) for the domino process were synthesized by addition of the lithiated alkyne (20) to various aldehydes (19); moreover, the substrates were accessible enantioselectively (in 95?% ee) by reduction of the corresponding ketone using the Noyori procedure.