title: Electrophilic Activation of α,β-Unsaturated Amides: Catalytic Asymmetric Vinylogous Conjugate Addition of Unsaturated γ-Butyrolactones.
abstract: Although catalytic asymmetric conjugate addition reactions have remarkably advanced over the last two decades, the application of less electrophilic α,β-unsaturated carboxylic acid derivatives in this useful reaction manifold remains challenging. Herein, we report that α,β-unsaturated 7-azaindoline amides act as reactive electrophiles to participate in catalytic diastereo- and enantioselective vinylogous conjugate addition of γ-butyrolactones in the presence of a cooperative catalyst comprising of a soft Lewis acid and a Brønsted base. Reactions mostly reached completion with as little as 1 mol % of catalyst loading to give the desired conjugate adducts in a highly stereoselective manner.
authors.affiliation: Institute of Microbial Chemistry (BIKAKEN), 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo, 141-0021, Japan), Fax: (+81) 3-3441-7589.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Institute of Microbial Chemistry (BIKAKEN), 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo, 141-0021, Japan), Fax: (+81) 3-3441-7589. nkumagai@bikaken.or.jp.
authors.forename: Naoya
authors.initials: N
authors.lastname: Kumagai
authors.affiliation: Institute of Microbial Chemistry (BIKAKEN), 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo, 141-0021, Japan), Fax: (+81) 3-3441-7589. mshibasa@bikaken.or.jp.
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Shibasaki
mesh_terms: D015107:4-Butyrolactone / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D058116:Lewis Acids / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: D000577:Amides; D002264:Carboxylic Acids; D058116:Lewis Acids; D014753:Vinyl Compounds; D015107:4-Butyrolactone
keywords: asymmetric catalysis; azaindoline; butenolide; conjugate addition; cooperative catalysis