title: Highly enantioselective, intermolecular hydroamination of allenyl esters catalyzed by bifunctional phosphinothioureas.
abstract: Bifunctional phosphinothiourea catalysts have been developed successfully for the highly regio- and enantioselective γ-hydroamination of allenyl and propargyl esters with N-methoxy carbamate nucleophiles to yield α,β-unsaturated γ-amino acid ester products. In the case of propargyl ester substrates, the reaction proceeds through reversible phosphinothiourea-catalyzed isomerization to the corresponding allenyl ester. The high enantioselectivity of the process is attributed to a cooperative conjugate addition of a thiourea-bound carbamate anion to a vinyl phosphonium ion resulting from covalent activation of the allenyl ester substrate.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Yuan-Qing
authors.initials: YQ
authors.lastname: Fang
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Tadross
authors.forename: Eric N
authors.initials: EN
authors.lastname: Jacobsen
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000586:Amination; D002384:Catalysis; D004952:Esters; D013237:Stereoisomerism; D013379:Substrate Specificity; D013890:Thiourea / Q000737:chemistry*
chemical_list: D000475:Alkenes; D004952:Esters; D013890:Thiourea