Intramolecular Nucleophilic Acyl Substitution Reaction of 3,4-Alkadienyl Carbonates Mediated by Ti(O-<i>i</i>-Pr)<sub>4</sub>/2 <i>i</i>-PrMgCl Reagent. Efficient Synthesis of Optically Active β,γ-Unsaturated Esters with an α-Substituent
作者:Yukio Yoshida、Sentaro Okamoto、Fumie Sato
DOI:10.1021/jo961401t
日期:1996.1.1
readily generated by the reaction of Ti(O-i-Pr)(4) with 2 i-PrMgCl, resulted in an intramolecular nucleophilic acyl substitution (INAS) reaction to afford vinyltitanium compounds 3 which, in turn, reacted with H(3)O(+), D(2)O, or iodine to give alpha-substituted beta,gamma-unsaturated esters 4 in good to excellent yields. The olefin moiety of the hydrolysis product 4 has (Z)-geometry mainly except for
用低价钛试剂二异丙氧基(eta(2)-丙烯)钛(1)处理3,4-链二烯基碳酸酯2a-i,该反应很容易通过Ti(Oi-Pr)(4)与2i反应生成-PrMgCl导致分子内亲核酰基取代(INAS)反应,得到乙烯基钛化合物3,后者再与H(3)O(+),D(2)O或碘反应生成α-取代的β, γ-不饱和酯4的收率为好至极好。水解产物4的烯烃部分主要具有(Z)几何形状,除了4h以外。从手性2f或2g开始,反应立体定向进行,得到仅具有(Z)-烯烃几何结构的旋光的α-取代的β,γ-不饱和酯4f或4g。