Solvent effects on the 9-hydroxymethylanthracene + N-ethylmaleimide Diels-Alder reaction. A theoretical study.
[structure: see text] The origin of the high reaction rates of the 9-hydroxymethylanthracene + N-ethylmaleimide Diels-Alder reaction in fluorous solvents and supercritical carbon dioxide is analyzed through a combination of regression analyses and theoretical calculations. Both approaches allow the solvent effects on the activation barrier (a decrease by solvophobic interactions, an increase by dipolarity-polarizability) to be attributed to the existence of a hydrogen bond between the two reactants in the transition state, refuting a previous hypothesis based on strong solvophobic interactions.
García
José I
JI
Departamento de Química Orgánica, ICMA, Universidad de Zaragoza-CSIC and IUCH, Facultad de Ciencias, Pedro Cerbuna 12, E-50009 Zaragoza, Spain.
Mayoral
José A
JA
Salvatella
Luis
L