THE REACTION OF LITHIUM TRIALKYL(1-ALKYNYL)BORATES WITH ORTHOESTERS IN THE PRESENCE OF TITANIUM TETRACHLORIDE. A NEW SYNTHESIS OF α,β-UNSATURATED CARBONYL COMPOUNDS
作者:Shoji Hara、Hidetaka Dojo、Akira Suzuki
DOI:10.1246/cl.1983.285
日期:1983.3.5
Trialkyl(1-alkynyl)borates readily available from trialkylboranes and lithium acetylides react with orthoesters in the presence of titaniumtetrachloride, followed by the oxidation with hydrogen peroxide and sodium hydroxide to give the corresponding α,β-unsaturated carbonyl compounds.
Treatment of lithium trialkylalkynylborates with acetyl chloride gave 2-oxa-3-borolenes (2). The enol borinates were oxidized by Jones reagent to highly substituted α,β-unsaturated ketones (4). The stability of 2 is ascribed to the steric hindrance of the B-alkyl groups and to the resonance contribution of the mesomeric structure 3.
Reactions of trialkylalkynylborates with 2-alkyl-1,3-dioxalan-2-ylium fluorosulphonates. Versatile direct routes to -αβ-unsaturated ketones, specifically protected 1,3-diketones and other ketonic species.
作者:Andrew Pelter、M.Eamon Colclough
DOI:10.1016/s0040-4039(00)84416-0
日期:1986.1
Pelter Andrew, Colclough M. Eamon, Tetrahedron, 51 (1995) N 3, S 811-828
作者:Pelter Andrew, Colclough M. Eamon
DOI:——
日期:——
HARA, SHOJI;DOJO, HIDETAKA;SUZUKI, AKIRA, CHEM. LETT., 1983, N 3, 285-286