Cp2TiCl2-catalyzed reaction of symmetrical alkynes with α,ω-dicarboxylic acid esters and ЕtAlCl2: An original pathway to С5-С6 cyclic ketones and tetrasubstituted furans

Abstract

An original method for the synthesis of С5-С6 cyclic ketones and tetrasubstituted furans was developed based on the Cp2TiCl2-catalyzed reaction of symmetrical alkynes and α,ω-dicarboxylates in the presence of Mg and ЕtAlCl2. The length of the hydrocarbon chain between carboxyl groups in a,ω-dicarboxylic acid esters affects the chemoselectivity of the reaction. The formation of 2-alkylidene and 2-alkenyl cyclopent(hex)an-1-ones occurred in the reaction with esters of glutaric and adipic acids. α,ω-Dicarboxylic acid esters with more than four methylene units between carboxyl groups gave rise to substituted furans. Stereochemistry of 2-alkenyl cyclopent(hex)an-1-ones was determined based on the analysis of experimental and theoretical data obtained from DFT calculations.