Chiral phosphoric acid catalyzed enantioselective inverse-electron-demand oxa-Diels-Alder reactions to synthesize chiral tricyclic tetrahydropyran derivatives

A series of enantioenriched tricyclic tetrahydropyran derivatives were achieved through chiral phosphoric acid catalyzed intramolecular inverse electron demand oxa-Diels-Alder (IEDODA) reactions, with good yields (up to 95%) and excellent stereocontrol (>20 : 1 dr, up to 99% ee). The achievement of such high enantioselectivity was ascribed to the rationally designed remote dual hydrogen bonding interaction, by which the conformation of the flexible substrate was well arranged by the catalyst in a reactive and stereoselective manner to participate in the transformation.