Methylenation of Aldehydes: Transition Metal Catalyzed Formation of Salt-Free Phosphorus Ylides

Abstract
A variety of terminal alkenes are produced in excellent yields by the rhodium(I)-catalyzed methylenation of aldehydes using TMSCHN2 and PPh3 [Eq. (1)]. These mild reaction conditions allowed the conversion of enolizable substrates and the chemoselective methylenation of aldehydes over ketones. TMS=trimethylsilyl.