MnO<sub>2</sub> as a terminal oxidant in Wacker oxidation of homoallyl alcohols and terminal olefins
作者:Rodney A. Fernandes、Gujjula V. Ramakrishna、Venkati Bethi
DOI:10.1039/d0ob01344g
日期:——
PdCl2/CrO3/HCl produced α,β-unsaturated ketonesfrom homoallyl alcohols, the present method provided orthogonally the β-hydroxy-methyl ketones. No overoxidation or elimination of benzylic and/or β-hydroxy groups was observed. The method could be extended to the oxidation of simple terminalolefins as well, to methyl ketones, displaying its versatility. An application to the regioselective synthesis of gingerol is
Traceless OH-Directed Wacker Oxidation-Elimination, an Alternative to Wittig Olefination/Aldol Condensation: One-Pot Synthesis of <i>α</i>,<i>β</i>-Unsaturated and Nonconjugated Ketones from Homoallyl Alcohols
作者:Venkati Bethi、Rodney A. Fernandes
DOI:10.1021/acs.joc.6b01899
日期:2016.9.16
A new method for one-pot synthesis of β-substituted and β,β-disubstituted α,β-unsaturated methyl ketones from homoallyl alcohols by sequential PdCl2/CrO3-promoted Wacker process followed by an acid-mediated dehydration reaction has been developed. Remarkably, internal homoallyl alcohols delivered regioselectively nonconjugated unsaturated carbonyl compounds under the same protocol. A new starting material-based
Reactivity in acid-catalyzed carbon-carbon heterolysis
作者:Weiguo Cao、Ihsan Erden、Richard H. Grow、James R. Keeffe、Jiangao Song、Mary B. Trudell、Teri L. Wadsworth、Fu-Pei Xu、Ji-Bin Zheng
DOI:10.1139/cjc-77-5-6-1009
日期:——
to carbocations plus a carbon-centered nucleofuge. The fragmentation mechanisms are shown to be A1 or A1(ion pair) except for the 2-arylnitrocyclopropanes which cleave in trifluoroacetic acid by a concerted mechanism. Rate comparisons among several unstrained substrate sets indicate that O-centered nucleofuges undergo acid-catalyzed heterolysis ca. 10 3 -10 4 faster than S-centered nucleofuges and ca
平衡和速率常数已经确定了酸催化的两种醇、9-xanthydrol 和对茴香基二苯基甲醇和两种硫化物、(9-xanthyl) 甲基硫化物和 (7-tropyl) 甲基硫化物的杂解。将这些数据与文献信息与酸催化 CC 杂解的速率常数进行了比较,其中包括几种(9-xanthyl)化合物、(7-tropyl)化合物、一组 3-芳基环丁酮和两种 2-芳基硝基环丙烷,所有这些都是碎片到碳正离子加上以碳为中心的离核剂。除了通过协同机制在三氟乙酸中裂解的 2-芳基硝基环丙烷外,裂解机制显示为 A1 或 A1(离子对)。几个无应变底物组之间的速率比较表明,以 O 为中心的核离心剂经历了酸催化的异解作用。10 3 -10 4 比以 S 为中心的离心机快 10 3 -10 4。10 9 -10 14 比此处使用的以 C 为中心的离心机快。有助于 CC 异种分解(及其有效性)的因素包括培养基的酸度(强);离核剂的
Isopropylmagnesium chloride-promoted unilateral addition of Grignard reagents to β-diketones: one-pot syntheses of β-tertiary hydroxyl ketones or 3-substituted cyclic-2-enones
作者:Rui Yuan、Dan Zhao、Li-Yuan Zhang、Xiang Pan、Yan Yang、Pei Wang、Hong-Feng Li、Chao-Shan Da
DOI:10.1039/c5ob02072g
日期:——
unilateral additions of Grignardreagents to acyclic or cyclic β-diketones were effectively promoted by sub-stoichiometric amounts of i-PrMgCl to afford β-tertiary hydroxyl ketones or 3-substituted cyclic-2-enones, respectively. Also, the addition of Grignardreagents to acyclic β-diketones followed by a reaction with cyclic β-diketones in a one-pot process was put forward. The reaction mechanism was discussed
Crossed aldol reaction of enol esters, stable carbon nucleophiles, with carbonylcompounds is effectively performed by the promotion of diethylaluminum ethoxide under mild conditions. This reaction is applicable not only to simple enol esters but also to lactones such as α-angelicalactone.