RETRACTED: Theoretical study of the mechanism, regio- and stereoselectivity of Diels-Alder reactions of 5-aryl-2-pyrones with substituted alkenes

Reason: this paper has been retracted because errors in the text and supplementary material were pointed out to the Editors after its publication. The MP2 numbers in the text were computed by an incorrect procedure, and the supplementary material does not correspond to the correct molecules.