Highly Controlled Chemoselectivity of Tin Enolate by Its Hybridization State. Anionic Complex of Tin Enolate Coordinated by Tetrabutylammonium Bromide as Halo Selective Reagent
作者:Makoto Yasuda、Keiko Hayashi、Yasuhiro Katoh、Ikuya Shibata、Akio Baba
DOI:10.1021/ja972190s
日期:1998.2.1
bromide (Bu4NBr) to neutral four-coordinated tin(IV) enolates 1(e). The highly coordinated enolates which attained a marked change in chemoselectivity have higher nucleophilicity to organichalides. In addition, they showed low nucleophilicitytoward carbonyl moieties by the coordination of the bromide anion, whereas carbonyl addition readily proceeds using the usual four-coordinated tin enolate. NMR studies
Catalytic Effect of Five-Coordinate Organotin Bromide or Tetraphenylstibonium Bromide on the Chemo- and Stereoselective Addition of Tin Enolate to<i>α</i>-Halo Ketone
tetraphenylstibonium bromide, similarly promoted the selective addition of tin enolates to the carbonyl moiety in α-halo ketones. The reaction with 2-chlorocyclohexanones and the enolates gave chlorohydrins bearing chloro- and hydroxyl groups in the cis-conformation. Chemoselective carbonyl addition to acyclic α-halo ketones was followed by effective cyclization to 2-(2-oxoethyl)oxiranes. The structural and bonding
Michael Addition of Stannyl Ketone Enolate to α,β-Unsaturated Esters Catalyzed by Tetrabutylammonium Bromide and an ab Initio Theoretical Study of the Reaction Course
作者:Makoto Yasuda、Kouji Chiba、Noriyuki Ohigashi、Yasuhiro Katoh、Akio Baba
DOI:10.1021/ja028853+
日期:2003.6.1
Michael addition of stannyl ketone enolates to alpha,beta-unsaturated esters was accomplished in the presence of a catalytic amount of tetrabutylammonium bromide (Bu(4)NBr). Other typical systems using lithium enolate or silyl enolate with catalysts (TiCl(4) or Bu(4)NF) failed to give the desired products. The bromide anion from Bu(4)NBr coordinates to the tin center in enolate to accelerate the conjugate
Imines et enamines stanniques: preparation et caracterisation
作者:Jean-Marie Brocas、Bernard De Jeso、Jean-Claude Pommier
DOI:10.1016/s0022-328x(00)98027-6
日期:1976.11
been obtained by two different routes: (1) reaction of organotin enolates with stannazane; (2) reaction of tributyltin chloride with a magnesium derivative of imine. The first method allows the preparation of the less hindered compounds, the reverse being true for the latter.