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结合环己烷的构象与能量关系,讨论[3,3]σ迁移反应的立体化学过程。[3,3]σ迁移反应生成的主产物经过的是椅式过渡态,生成的次要产物经过的是扭船式过渡态,而不是以前认为的船式过渡态。 相似文献
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本文提出一种确定Huckel-Hubbard(H-H)参数的方法,并将H-H 理论首次推广用于Witting重排,硫叶立德重排,烯丙基亚砜重排等[2,3]σ键迁移重排反应的研究.我们考虑协同机理,构造了Huckel和Mobius 两种不同反应途径的基态和低激发态势能面,详细讨论了热反应和光化学反应的立体选择性和反应的活化能 相似文献
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报道烯(炔)基硫醚与α-重氮羰基化合物, 在[RuCl2(p-cymene)]2催化下, 经由金属卡宾发生硫叶立德[2,3]-σ重排反应(Doyle-Kirmse反应). 在Ru(II)作用下, α-重氮羰基化合物与烯丙基硫醚的反应以较好收率生成相应的[2,3]-σ重排产物高烯丙基硫醚. 同样条件下与炔丙基硫醚的反应则生成[2,3]-σ重排产物联烯和呋喃衍生物, 后者是联烯进一步在Ru(II)作用下重排的产物. 相似文献
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本文对含有手性碳原子的[3,3]σ迁移反应的立体化学过程进行了讨论,重点讨论了含有手性碳原子的Cope重排和Claisen重排的产物及其生成的立体化学过程。 相似文献
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磷杂环戊二烯在探索磷化学的研究中发挥了重要的作用,并广泛应用于配位化学、催化和有机光电材料等领域.[1,5]-σ键迁移(以下简称[1,5]迁移)是磷杂环戊二烯的一类重要反应.该迁移主要是由于磷杂环戊二烯弱的芳香性和环外磷上取代基的σ键与环内二烯体的反键轨道存在一定的σ-π*超共轭效应等特性所共同造成的.该反应自发现以来就成为磷杂环戊二烯衍生化的重要和有效手段.主要介绍了近几年来人们利用磷杂环戊二烯[1,5]迁移特性设计与合成新型有机磷化合物和含磷光电材料的研究进展. 相似文献
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联苯胺重排是N,N’-二芳基肼在酸催化下生成4,4’-二氨基联苯的反应。对该重排反应曾有π络合物和极性过渡态两种代表性的机理。但通过同位素效应动力学研究确定该重排反应是σ迁移反应型的周环反应。本文介绍了对联苯胺重排反应机理的研究及其代表性的实例。 相似文献
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The rearrangement of terminal allylic hexafluoroisopropyl sulfides to the internal olefinic sulfide occurs under either photochemical or thermal conditions. In the case of the formation of and isomers, the isomer was predominant. The rearrangement is suggested as a unimolecular, associative radical mechanism, kinetic studies, use of inhibitors, or radical initiator. 相似文献
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Russian Journal of Organic Chemistry - 相似文献
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Regioselective generation of the C(2)-carbocation a of tricyclo[4.2.2.01,5]decane ( 1 ) by treatment of both corresponding epimeric alcohols 5 and 6 with BF3 and trapping the rearranged tricyclo[5.3.0.04,8]decan-7-yl carbocation b with Et3SiH as hydride-ion donor (ionic hydrogenation) gives the corresponding hydrocarbon 3 as sole product in almost quantitative yield. The latter is a known intermediate in the Lewis-acid-catalyzed rearrangement of 1 to adamantane ( 4 ). 相似文献
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In the presence of AlBr3 in CS2 at temperatures below 0°, syn-tricyclo[4.2.1.12,5]decane ( 1 ) isomerizes exclusively to anti-tricyclo[4.2.1.12,5]decane ( 2 ) at a higher rate than the latter rearranges to 2-exo,3-exo-trimethylene-8,9,10-trinorbornane ( 4 ). However, at temperature above 0°, the anti-isomer 2 isomerizes to 4 faster than 1 to 2 and 4 . As a consequence, hydride abstraction occurs at C(3) (→carbocation a , which rearranges to carbocation b (anti-skeleton)) in the syn-isomer 1 , and more readily at C(9) (→carbocation c ) than at C(3) (→carbocation b ) in the anti-isomer 2 . 相似文献
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Oleksandr V. Grytsai Marian V. Gorichko Vladimir B. Golovko 《Tetrahedron: Asymmetry》2013,24(13-14):817-821
The regio- and diastereospecific Wagner-Meerwein-type rearrangements of the potassium cyanide adducts of camphor-derived substituted 1-bromo-N-nitrobicyclo[2.2.1]heptan-2-imines under acidic conditions have been investigated. The selective formation of bromonorbornene derivatives has been demonstrated in the case of rearrangements involving intermediate α-bromocarbocations containing vicinal hydrogen atoms. In all other cases, hydrolysis of the intermediates resulted in the formation of a carbonyl group. The simplicity of this transformation opens up a novel and straightforward synthetic pathway to enantiopure derivatives of bridgehead-substituted norbornane carboxamides in just three steps, starting from 1-bromonorbornanones. 相似文献
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A. G. Makarenko P. I. Parkhomenko A. B. Rozhenko A. A. Grigor'ev M. V. Rybakova Y. V. Bezuglyi 《Chemistry of Heterocyclic Compounds》1994,30(9):1106-1109
The reaction of 4-bromo-2-thiolene 1,1-dioxide with thiosemicarbazide and thiosemicarbazones gave 2-iminoperhydrothieno[3,4]-d]thiazole 5,5-dioxides, which contain a nitrogen function at the imino group. The recyclization of these compounds was studied.Institute of Bioorganic Chemistry and Petyrochemistry, 252160 Kiev. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1274–1277, September, 1994. Original article submitted July 25, 1994. 相似文献