检查了 3-取代的甲苯磺酸环丁基酯(X=Ar、Cl 和 OEt)的乙酰水解,给出了速率和产物分布。对于烷基和芳基取代的化合物,限速步骤导致形成桥连的环丁基阳离子,然后重排为环丙基羰基/高烯丙基离子。3-芳基衍生物溶剂分解的 ρ 值为 -1.5,表明一些电荷转移到 3-位。3-氯环丁基甲苯磺酸酯反应仅产生转化的3-氯环丁基乙酸酯。3-乙氧基衍生物产生~1:1的相应乙酸酯混合物。有关这些反应的更多信息是通过 MP2/6-31 * 理论水平的 ab initio MO 计算获得的
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
Enantioselective Baeyer–Villiger Oxidation Catalyzed by Palladium(II) Complexes with Chiral <i>P,N</i>-Ligands
作者:Andrei V. Malkov、Frédéric Friscourt、Mark Bell、Martin E. Swarbrick、Pavel Kočovský
DOI:10.1021/jo800246g
日期:2008.6.1
Asymmetric Baeyer–Villiger reaction of symmetrical cyclobutanones 1a−j with urea−hydrogen peroxide (UHP) can be catalyzed by a complex of Pd(II) and the new terpene-derived P,N-ligand 7. The resulting lactones 2a−j were obtained in high yields and with good enantioselectivity (≤81% ee).
We report the metal-free chalcogenation of cycloketone oxime esters with dichalcogenides via a radical process. Because of the metal-free condition and use of readily accessible dichalcogenides, this method is an effective and green strategy for the synthesis of chalcogen-substituted butyronitrile.
Baeyer–Villigeroxidation of cyclobutanones is achieved in current developed protocol with 10-methylacridinium perchlorate (AcrH+ClO4−) as a novel organocatalyst both with irradiation at room temperature and without irradiation at elevated temperature. Excellent yields of the corresponding lactones are obtained and the possible mechanism has been proposed.
N'-dioxide-Sc(III) complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active ε- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratoryaptitude, were