title: Catalytic asymmetric inverse-electron-demand oxa-Diels-Alder reaction of in situ generated ortho-quinone methides with 3-methyl-2-vinylindoles.
abstract: The first catalytic asymmetric inverse-electron-demand (IED) oxa-Diels-Alder reaction of ortho-quinone methides, generated in situ from ortho-hydroxybenzyl alcohols, has been established. By selecting 3-methyl-2-vinylindoles as a class of competent dienophiles, this approach provides an efficient strategy to construct an enantioenriched chroman framework with three adjacent stereogenic centers in high yields and excellent stereoselectivities (up to 99 % yield, >95:5 d.r., 99.5:0.5 e.r.). The utilization of ortho-hydroxybenzyl alcohols as precursors of dienes and 3-methyl-2-vinylindoles as dienophiles, as well as the hydrogen-bonding activation mode of the substrates met the challenges of a catalytic asymmetric IED oxa-Diels-Alder reaction.
authors.affiliation: Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, School of Chemistry and Chemical Engineering, Jiangsu Normal University, Xuzhou, 221116 (China).
authors.forename: Jia-Jia
authors.initials: JJ
authors.lastname: Zhao
authors.forename: Si-Bing
authors.initials: SB
authors.lastname: Sun
authors.forename: Sai-Huan
authors.initials: SH
authors.lastname: He
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.forename: Feng
authors.initials: F
authors.lastname: Shi
keywords: asymmetric catalysis; cycloaddition; enantioselectivity; heterocycles; organocatalysis