title: Synthesis of 6H-dibenzo[b,d]pyran-6-ones using the inverse electron demand Diels-Alder reaction.
abstract: A set of coumarin-fused electron-deficient 1,3-dienes was synthesized, which differ in the nature of the electron-withdrawing group (EWG) at the terminus of the diene unit and (when EWG = CO(2)Me) the nature and position of substituents. These dienes reacted with the enamine derived from cyclopentanone and pyrrolidine to afford the corresponding cyclopenteno-fused 6H-dibenzo[b,d]pyran-6-ones, most likely via a domino inverse electron demand Diels-Alder (IEDDA)/elimination/transfer hydrogenation sequence. The parent diene (EWG = CO(2)Me, no substituents) was reacted with a range of electron-rich dienophiles (mostly enamines) to afford the corresponding 6H-dibenzo[b,d]pyran-6-ones or their nondehydrogenated precursors, which were aromatized upon treatment with a suitable oxidant. The enamines could either be synthesized prior to the reaction or generated in situ. The syntheses of 30 dibenzopyranones are reported.
authors.affiliation: Department of Chemistry, Memorial University, St. John's, NL, Canada, A1B 3X7.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Pottie
authors.forename: Penchal Reddy
authors.initials: PR
authors.lastname: Nandaluru
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Benoit
authors.forename: David O
authors.initials: DO
authors.lastname: Miller
authors.forename: Louise N
authors.initials: LN
authors.lastname: Dawe
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Bodwell
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D003374:Coumarins / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D004583:Electrons; D015394:Molecular Structure; D011090:Polyenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000475:Alkenes; D003374:Coumarins; D011090:Polyenes