Reactions of diethyl 1-lithio-1-trimethylsilylmethylphosphonate (1) and l-trimethylsilyl-l- phenylthiomethyl-lithium (2) with representative aldehydes and ketones are reported which provide useful routes to diethyl vinylphosphonates (6a-g) and vinyl phenylthioethers (18a-g) by loss of MerSiOLi from the presumed intermediate resulting from attack of the organolithium reagent at the carbonyl group. It was found that the exocyclic ...