Freshly prepared potassium bis(trimethylsilyl)amide (K[N(SiMes3)2], KHMDS) was added to a cloudy suspension of (triphenylphosphoranylidene) acetonitrile to generate the anionic ylid that was first prepared as the sodium salt by Bestmann and Schmidt in 1987. Addition of 18-crown-6 and CO to this mixture, by analogy with the pioneering work from the Gessner group, led to loss of triphenylphosphine (detected by 31 P NMR spectroscopy) and clean formation of the target compound [K(18-crown-6)][NCCCO]