Highly E-selective solvent-free Horner–Wadsworth–Emmons reaction catalyzed by DBU
作者:Kaori Ando、Kyohei Yamada
DOI:10.1039/c1gc15134g
日期:——
The solvent-free Horner–Wadsworth–Emmons reaction of triethylphosphonoacetate with a variety of aldehydes was catalyzed by DBU in the presence of K2CO3 to give E-α,β-unsaturated esters highly selectively (99:1 for most of the reactions). The reaction with ketones gave trisubstituted olefins with good to high E-selectivity by DBU-Cs2CO3.
这 溶剂无Horner–Wadsworth–Emmons的反应 膦酸三乙酯 与各种 醛类DBU在K 2 CO 3的存在下催化得到E -α,β-不饱和酯类高度选择性(大多数反应为99 :1)。与之反应酮类 给出三取代 烯烃DBU-Cs 2 CO 3具有良好的电子选择性,甚至具有很高的电子选择性。
Solvent-free Horner–Wadsworth–Emmons reaction using DBU
作者:Kaori Ando、Kyohei Yamada
DOI:10.1016/j.tetlet.2010.04.072
日期:2010.6
The solvent-free Horner-Wadsworth-Emmons reaction with a variety of aldehydes using 1.5 equiv of DBU gave E-alpha,beta-unsaturated esters and ketones in high yields. The E-selectivity was high and the used DBU was recovered. (C) 2010 Elsevier Ltd. All rights reserved.
Stereoselective radical additions of γ-oxy-α,β-unsaturated ester derivatives; 1,2-asymmetric induction in acyclic and cyclisation systems
Examination was made of 1,2-asymmetric induction in the addition of alkyl radicals to gamma-oxy-alpha,beta-unsaturated ester derivatives 1 and 2 prepared from ethyl lactate and (R)-2,3-0-isopropylideneglyceraldehyde 3, respectively. The addition reactions of hexyl, cyclohexyl and 3-phenylpropyl radicals to (Z)-2 derived from aldehyde 3 gave beta-addition products with syn-stereoselectivity (syn:anti = 8.6:1-syn only). The reactions of (E)-2 were non-stereoselective. Based on allylic strain, a transition-state model for the syn-stereoselectivity is proposed. 1,2-Asymmetric induction was carried out in radical cyclisation to synthesize optically active cyclohexane derivatives.
YAMAMOTO, KEIJI;YAMAMOTO, NORIO, CHEM. LETT.,(1989) N, C. 1149-1152