1.1-Alkenyl-2,5-dimethyl-4-piperidones were condensed with acetylene under a pressure of 5 atra with formation in high yield of the corresponding 1-alkenyl-4-ethynyl-2,5-dimethyl-4-piperidinols (I)-(III) in the form of mixtures of stereoisomers, which were separated into individual compounds by fractional crystallization of the; hydrochlorides.2.Esterification of the piperidinols (I)-(III) with benzoyl and phenoxyacetyl chlorides gave the benzole and phenoxyacetic esters (IV)–(VIII), which were subjected to pharmacological tests for surface anesthesia. The most valuable of the esters examined was the benzoic ester of 1-(2-butenyl)-4-ethynyl-2,5-dimethyl-4-piperidinol (VI), which in 1% solution has the same activity as tetracaine (at the same concentration), but a toxicity that is less than that of tetracaine by a factor of almost 3.