Synthesis of ?-monosubstituted ?,?-unsaturated amides withZ-selectivity using diphenylphosphonoacetamides
作者:Satoshi Kojima、Tsugihiko Hidaka、Yuko Ohba
DOI:10.1002/hc.20054
日期:——
The utility of diphenylphosphonoacetamides [(PhO)2P(O)CH2CONRR′] as Horner–Wadsworth–Emmons reagents was examined with five different patterns of substitution upon the amide nitrogen atom (2a: R, R′ = CH2Ph; 2b: R = CH2Ph, R′ = H; 2c: R = Me, R′ = OMe; 2d: R, R′ = Ph; 2e: R, R′ = (CH2)4). The reaction of 2a was found to be Z-selective for aromatic aldehydes with selectivities up to 95:5. Reagent 2b
Ru-Based Catechothiolate Complexes Bearing an Unsaturated NHC Ligand: Effective Cross-Metathesis Catalysts for Synthesis of (<i>Z</i>)-α,β-Unsaturated Esters, Carboxylic Acids, and Primary, Secondary, and Weinreb Amides
作者:Zhenxing Liu、Chaofan Xu、Juan del Pozo、Sebastian Torker、Amir H. Hoveyda
DOI:10.1021/jacs.9b02318
日期:2019.5.1
compounds is illustrated through two representative applications: an eight-step, 15% overall yield, and completely Z-selective route leading to an intermediate that may be used in synthesis of stagonolide E (vs 11 steps, 4% overall yield and 91% Z, previously), and a five-step, 25% overall yield sequence to access a precursor to dihydrocompactin (vs 13 steps and 5% overall yield, formerly).
尽管取得了显着进展,但用于制备 (Z)-α,β-不饱和羰基化合物的烯烃复分解方法仍然很少,适用于合成多种生物活性分子。特别需要的是可以由基于钌的催化剂促进的转化,因为这样的实体将允许直接获得羧酸酯和酰胺或酸(与基于钼或钨的亚烷基相反)。在这里,我们详细介绍了如何根据通过计算和实验研究获得的机理洞察,发现一种易于获得的儿茶酚硫合钌配合物,该配合物可用于生成许多 α,β-不饱和羰基化合物,产率高达 81%,≥98: 2 Z/E 比率。我们首次证明,通过使用带有不饱和 N-杂环卡宾 (NHC) 配体的复合物,源自缺电子性更强的酯、酸和 Weinreb 酰胺(相对于伯酰胺或仲酰胺)的产物可以高效合成并具有高度立体化学控制。通过两个代表性应用说明了合成生物活性化合物的新进展的重要性:八步、15% 的总产率和完全 Z 选择性路线,导致可用于合成 stagonolide E 的中间体(vs 11步骤,4%
Application of Organocerium Reagents for the Efficient Conversion of<i>Z</i>-α,β-Unsaturated Weinreb Amides to<i>Z</i>-α,β-Unsaturated Ketones
The reactions of Z-rich unsaturated Weinreb amides with organolithium and organocerium reagents were examined. Taking in consideration both the extent of geometry retention and cleanness of the reaction, organocerium reagents were more effective for the conversion to Z-α,β-unsaturated ketones.
研究了富含 Z 的不饱和 Weinreb 酰胺与有机锂和有机铈试剂的反应。考虑到几何形状的保留程度和反应的清洁度,有机铈试剂在转化为 Z-α,β-不饱和酮方面更为有效。