Comprehensive DFT study on site-, regio-, and stereoselectivity of diels-alder reactions leading to 5-hydroxybenzofurans

Abstract

Diels-Alder reactions between the substituted furans 1a-1c and Danishefsky's diene (2), yielding 5-hydroxybenzofurans, were studied by density functional theory [B3LYP/6-31G(d) level] in benzene as solvent (SP/CPCM). The mechanistic details of these reactions, especially with respect to regio-, site-, and stereochemistry were analyzed in detail. Moreover, the extrusion of nitrous acid from the Diels-Alder cycloadducts and the formation of the aromatic products were also explained in order to give a total description of the complete domino processes. Some Diels-Alder reactions leading to 5-hydroxybenzofurans were studied at the B3LYP/6-31G(d) level of theory in benzene as solvent (SP/CPCM). DFT calculations on the transition structures were carried out for all the possible reaction channels (site, regio-, and stereoisomeric channels were included in this study). Additionally, a description of the complete domino processes was performed.