Stereoselective Conjugate Addition of Benzyl Phenylsulfonyl Carbanions to Enoates Derived from <scp>d</scp>-Mannitol
作者:André R. G. Ferreira、Guilherme V. M. de A. Vilela、Mauro B. Amorim、Kátia P. Perry、Antônio J. R. da Silva、Ayres G. Dias、Paulo R. R. Costa
DOI:10.1021/jo035427d
日期:2004.6.1
The conjugate addition of benzylic phenylsulfonyl carbanions (2a‘−d‘) to enoates derived from d-(+)-mannitol (E- or Z-1a−c) was studied using THF and THF/HMPA as solvent. Under kinetic conditions (−78 °C), enoate E-1a,b led to a mixture of syn-(R,S) and anti-(S,S) adducts (55/45), and syn-(R,S) adducts were the main product obtained (∼90/10) from enoate Z-1a. Under thermodynamic conditions (−78 °C
共轭加成苄苯基磺酰基负碳离子(的2A ' - d ')从衍生enoates d - (+) -甘露糖醇(ë -或ž - 1A - C ^)用THF和THF / HMPA作为溶剂的研究。下动力学条件(-78℃),烯酸甲酯ë - 1A,B导致的混合物顺式- (- [R ,小号)和反- (小号,小号)加合物(55/45),以及顺式- (- [R ,小号)加合物是从烯醇酸酯获得的主要产物(〜90/10)Z - 1a。在热力学条件下(-78°C到室温),尽管受体中双键的几何形状也优先形成(-90/10 )syn-(R,S)加合物。烯酸酯1C(Ë / Ž = 57/43),在α位置带有一个额外的苄基,也与负碳离子反应,2 ' ,A,B,热力学条件下,从而导致顺-adducts在良好的德(在三个控制新生成的立体成因中心)。将加合物定量转化为相应的β-γ-二取代的γ-丁内酯和α,β,γ-三取代的γ-丁内酯。这些内酯的1