title: PBu3-mediated vinylogous Wittig reaction of α-methyl allenoates with aldehydes and mechanistic investigations.
abstract: A highly stereoselective PBu(3)-mediated vinylogous Wittig olefination between α-methyl allenoates and a variety of aldehydes is presented as the first example of a practical and synthetically useful vinylogous Wittig reaction. Mechanistic experiments including deuterium-labeling, intermediate entrapment, and NMR monitoring have been deliberately conducted. On the basis of mechanistic investigations, a reliable mechanism for the vinylogous Wittig reaction is proposed, which features a water/phosphine-coassisted allylic phosphorus ylide 1,3-rearrangement pathway, rather than previous retro-Diels-Alder ones. It is noteworthy that mechanistic findings in this work also provide supportive evidence for typical mechanisms of important phosphine-mediated reactions of allenoates.
authors.affiliation: The State Key Laboratory of Elemento-Organic Chemistry and Department of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, People's Republic of China.
authors.forename: Silong
authors.initials: S
authors.lastname: Xu
authors.forename: Rongshun
authors.initials: R
authors.lastname: Chen
authors.forename: Zhengjie
authors.initials: Z
authors.lastname: He