It was shown previously in [i, 2] that 3-methyl-5-arylsulfonylpent-3-en-i-ynes, which are obtained from 3-methyl-5-hydroxypent-3-en-l-yne, an intermediate in the synthesis of vitamin A [3], are converted under the action of secondary amines into 3-methyl-5-arylsulfonylpent-3- en-2-ones~