Jump to main content
Jump to site search


A molecular electron density theory study on [3+2] cycloaddition reaction of thiocarbonyl ylides toward hetaryl thioketones

Abstract

Utilizing the newly proposed molecular electron density theory (MEDT), a detailed study was performed on the [3+2] cycloaddition (32CA) reaction of thiocarbonyl ylide TCY 2 toward thioketone THK 3 at the B3LYP/6-31G(d) computational level. In the gas phase, this reaction displays a very low activation total electronic energy of 1.6 kcal/mol arising from the pseudo(di)radical (pdr) character of TCY 2 distinguished by an electron localization function (ELF) analysis over the ground-state electronic structure (GES) of this species. A further exploration of the relative Gibbs free energies in the presence of THF at -40˚C indicates that, in excellent agreement with the experimental findings, the C1-C4 regioisomeric channel is kinetically preferred over the C1-S5 one leading to the formation of cycloadduct CA 4 as the sole product. While, due to the high global nucleophilicity index of TCY 2 and the high global electrophilicity index of THK 3, a high polar 32CA reaction between reagents is expected, this pdr-type 32CA reaction displays a non-polar character. The entirely C1-C4 regioselectivity can be explained via probing molecular electrostatic potential (MEP) maps which portray a huge electrostatic repulsion between two interacting fragments of the transition state (TS) involved in the unfavorable C1-S5 regioisomeric channel. An ELF analysis over the most relevant points located along the intrinsic reaction coordinate (IRC) profile of the TS connecting separate reagents to CA 4 establishes a non-concerted two-stage one-step molecular mechanism for the non-polar pdr-type 32CA reaction of TCY 2 toward THK 3.

Back to tab navigation

Publication details

The article was received on 26 Apr 2018, accepted on 07 Jun 2018 and first published on 07 Jun 2018


Article type: Paper
DOI: 10.1039/C8NJ02021C
Citation: New J. Chem., 2018, Accepted Manuscript
  •   Request permissions

    A molecular electron density theory study on [3+2] cycloaddition reaction of thiocarbonyl ylides toward hetaryl thioketones

    A. Asr, M. Aghaie, S. Emamian and H. Aghaie, New J. Chem., 2018, Accepted Manuscript , DOI: 10.1039/C8NJ02021C

Search articles by author

Spotlight

Advertisements