Synthesis of 3-alkylidene-piperidin-4-ones via one-pot cascade transylidation–olefination

3-Alkylidene-piperidin-4-ones with diverse C-5 substitution patterns are synthesized via a one-pot cascade transylidation–olefination sequence. Tributylphosphorus ylides show distinct higher reactivity as compared to triphenyl analogs. t-Butanol is the solvent of choice for transylidation, while the Wittig olefination of aliphatic aldehydes requires MeCN as the solvent.