Abstract

Haydar A. Mohammad-Salim¹and Hassan H Abdallah²

DOI : http://dx.doi.org/10.13005/ojc/350512

This study presents the intramolecular [2+2] cycloaddition reaction of ketenes to form cyclobutanones using B3LYP-D3/6-311++G(d,p) level of approximation. The concerted mechanism path was studied in detail. The structures of all intermediates and transition states were located using same level of theory. The influences of the substituents (-H, -CH3, -NH2, -F, -OH and –CN) were also discussed. The analysis of stationary points and the energetic parameters indicates that the substituted ketene with –CN group has the highest activation energy; however, ketene with –NH2 group has the lowest one. Conversely, in-tramolecular [2+2] cycloaddition records the highest degree of asynchronicity with –NH2 group and lowest with –CN group. The calculated thermodynamic parameters at room temperature have been listed and analyzed. The global and local properties of reactants involved in the intramolecular [2+2] cycloaddition reactions and the Fukui functions for an electrophilicity and local electrophilicity were also elucidated for carbon centers of each reactant.

DFT; Mechanism; Ketenes; [2+2] Cycloaddition

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