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
The palladium-catalysed reductive addition of aryl iodides to propargyl alcohols: a route to /gg,/gg-diaryl allylic alcohols
作者:A. Arcadi、S. Cacchi、F. Marinelli
DOI:10.1016/s0040-4020(01)96756-0
日期:1985.1
The reaction of aryliodides with ethynyl and arylethynyl,dialky l carbinols in the presence of the tri- or dialkylammonium formate-palladium reagent provides a convenient route to γ,γ-diarylallylic alcohols. In the presence of arylethynyl,alkylcarbinols a lack of regioselectivity was observed and mixtures of ß,γ-, γ,γ-diarylallylic alcohols, and α,ß-unsatu rated ketones were obtained.
The reaction of β-substituted-α,β-enones and -enals with aryl halides in the presence of a palladium catalyst has been investigated. The outcome of the reaction was found to be greatly dependent on the nature of the added base. Tertiary amines tend to favour the formation of conjugate addition-type products while sodium bicarbonate or sodium acetate that of vinylic substitution products. Usually, the