Mechanistic density functional theory study of the Claisen Rearrangement Diels-Alder Cycloaddition domino sequence for the synthesis of the caged garcinia xanthone

The mechanism of the tandem Claisen-Rearrangement-Diels-Alder-Cycloaddition reactions of the caged garcinia xanthone derivatives has been investigated and optimized by density functional theory (DFT) calculations studies at the B3LYP/6-31G+(d) level of theory. Hence, this study attempts to exploit and to show the favored reaction path leads in the step of a Claisen-Rearrangement-Diels-Alder-Cycloaddition reaction and to determinate the thermodynamic and kinetic products. For this purpose, an energy profile was determined by the optimization of the geometries of reactants, products and the corresponding transition-state (TS). The intrinsic reaction coordinate (IRC) analyses were made. Fukui functions, electrostatic potential surfaces and HOMO-LUMO energy of the component 1-O-methyl forbesione 1 were computed at the same level of theory. The Hirshfeld surface analysis indicates that the major contributions for the 1-O-methyl forbesione 1 packing are H center dot center dot center dot H (65.1%), H center dot center dot center dot O (23.2%) and H center dot center dot center dot C (9.7%) interactions. (C) 2019 Elsevier B.V. All rights reserved.