title: (E)- and (Z)-stereodefined enol phosphonates derived from β-ketoesters: stereocomplementary synthesis of fully-substituted α,β-unsaturated esters.
abstract: A versatile, robust, and stereocomplementary synthesis of fully-substituted (E)- and (Z)-stereodefined α,β-unsaturated esters 3 from accessible α-substituted β-ketoesters 1via (E)- and (Z)-enol phosphonates was achieved. The present method involves two accessible reaction sequences: (i) (E)- and (Z)-stereocomplementary enol phosphorylations of a wide variety of β-ketoesters 1 (24 examples; 71–99% yield, each >95: 5 ds), and (ii) (E)- and (Z)-stereoretentive Suzuki–Miyaura cross-coupling (16 examples; 71–91% yield, >81/19 ds) and Negishi cross-coupling (32 examples; 65–96% yield, >95 : 5 ds) using (E)- and (Z)-enol phosphonates 2. 1H-NMR monitoring for a key reactive N-phosphorylammonium (imidazolium) intermediate I and an application in the synthesis of both (E)- and (Z)-tamoxifen precursors 6 are described.
authors.affiliation: Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan. tanabe@kwansei.ac.jp.
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Nakatsuji
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Ashida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hori
authors.forename: Yuka
authors.initials: Y
authors.lastname: Sato
authors.forename: Atsushi
authors.initials: A
authors.lastname: Honda
authors.forename: Mayu
authors.initials: M
authors.lastname: Taira
authors.forename: Yoo
authors.initials: Y
authors.lastname: Tanabe
mesh_terms: D004952:Esters / Q000138:chemical synthesis* / Q000737:chemistry; D063065:Organophosphonates / Q000138:chemical synthesis* / Q000737:chemistry; D010766:Phosphorylation; D066244:Proton Magnetic Resonance Spectroscopy; D013237:Stereoisomerism; D013629:Tamoxifen / Q000737:chemistry
chemical_list: D004952:Esters; D063065:Organophosphonates; D013629:Tamoxifen