A method for the preparation of terminal acetylenes
摘要:
A new pathway is proposed for the preparation of terminal acetylenes entailing the condensation of acid chlorides with phenylacetylene, isomerization of the acetylenic ketones with displacement of the oxo group and triple bond in the ketoacetylenic fragment, and subsequent alkaline cleavage of the isomerized ketones.
A method is suggested for isomerization of alpha-acetylenic ketones with migration of the oxo group from position 1 to position 3 and of the triple bond from position 2 to position 1 of the ketoacetylenic fragment; it consists of addition of Et2NH at the triple bond of the ketone, conversion of the adduct to the imminium salt with POCl3, followed by alkaline hydrolysis. The isomerization is achieved in one preparative stage without isolation of intermediate compounds.