Summary 1. Acid chlorides react readily in the presence of zinc chloride to cleave the tetrahydropyran ring, forming 5-chloroamyl esters. 2. 5-Diethylaminopentanol-1 has been prepared in 44.5% over-all yield in three steps starting with benzoyl chloride and tetrahydropyran in the presence of zinc chloride, followed by replacement of the chlorine atom by a diethylamino group and hydrolysis.