Water → 2,6-Diphenyl-4-piperidone 1,2-Hexadecylene Ketal

Participants

Reaction Steps

A solution of 14.6 g (58.0 mmol) of 2,6-diphenyl-4-piperidone and 12.2 g (64 mmol) of p-toluenesulfonic acid monohydrate in 500 mL of toluene is refluxed and the azeotroping water is collected in a Dean Stark trap. When 1 mL of water is collected, 15.0 g (58.0 mmol) of 1,2-hexadecanediol (Aldrich) is added and the reaction is refluxed until another 1 mL of water is collected. The reaction mixture is cooled to room temperature and made basic with 50% aqueous sodium hydroxide solution. The organic layer is separated and the aqueous phase is extracted with toluene (2×100 mL). The combined organic phases are dried over anhydrous magnesium sulfate and the solvent is removed under reduced pressure. 11.0 g (38% yield) of the title compound is isolated after purification by liquid chromatography (LC) (silica gel, ethyl acetate/hexane) followed by recrystallization from ethanol: mp 63°-70° C.

Provenance & Evidence