Phosphoniosilylation of alpha,beta-enones with TBSOTf and triphenylphosphine at 0 degrees C affords 3-tert-butyldimethylsilyloxyalk-2-enylphosphonium salts, which undergo facile nucleophilic substitution with various nucleophiles to give 3-substituted silyl enol ethers in good yields. (C) 1999 Elsevier Science Ltd. All rights reserved.