关键词: 环丙烷化反应; 炔丙型硫Ylide; Trans-2-乙炔基环丙烷羧酸酯; 密度泛函理论; 过渡态

Abstract:

The cyclopropanation of propargyl sulfur Ylide with acrylate usually gave poor yield because of several competing reactions such as [2,3]-σ atropic rearrangement were also involved in this system. In our research, a higher yield(75%) and high diastereoselectivity(96%d.e.) for trans-2-ethynyl cyclopropane carboxylate were obtained by changing the structure of sulfur ylide and optimizing the reaction conditions. The mechanism and diastereoselectivity of the reaction were studied via the density functional theory method. High selectivity toward trans cyclopropanes are predicted on the basis of the relative activation energies of diastereomeric torsional transition states and the thermodynamic satbility of products. The energy differences between these transition states could be rationalized with the help of weak intramolecular stereoelectronic interactions.

Key words: Cyclopropanation; Propargylic sulfur Ylide; trans-2-Ethynyl cyclopropane carboxylate; Density functional theory; Transition state