Stereoselective epoxidation of cis-3,4-disubstituted-(CH2X)-cyclobutenes with dimethyldioxirane and peroxy acids. Experimental and computational evidence for a syn-orienting electrostatic effect
作者:Mauro Freccero、Remo Gandolfi、Mirko Sarzi-Amadè
DOI:10.1016/s0040-4020(99)00630-4
日期:1999.9
The epoxidation reactions of a series of cis-3,4-disustituted-(CH2X)-cyclobutenes 1–8 with dimethyldioxirane (DMD) and mClPBA have been investigated with both reagents. A remarkable syn diastereoselectivity in the formation of the epoxide has been observed for substrates bearing electron withdrawing substituents. Transition structures for epoxidations of 3,4-dimethylcyclobutene (1), diastereoisomeric
Leigh, William J.; Zheng, Kangcheng; Clark, K. Brady, Canadian Journal of Chemistry, 1990, vol. 68, # 11, p. 1988 - 1997
作者:Leigh, William J.、Zheng, Kangcheng、Clark, K. Brady
DOI:——
日期:——
High selectivities in electrophilic additions to cyclobutene compounds
作者:Laurence Mévellec、Michel Evers、François Huet
DOI:10.1016/s0040-4020(96)00945-3
日期:1996.11
Epoxidation of 2, 3, 4 with m-CPBA mainly led to the cis-attack products whereas 1 and 6 led to the other selectivity. The result was reversed, from 4, with Payne's reagent Bromohydroxylation of 4 involved an intermediate bromonium ion syn to the substituents. Haloselenylations occurred with the syn-selectivity from 1, 2, 3 and 4, to the anti-selectivity from 6, and without selectivity from 5. NOE enhancement measurements and several chemical correlations led to the stereochemical assignments. Formation of the intramolecular reaction products 24 and 25 was also pointed out. Copyright (C) 1996 Elsevier Science Ltd
Freccero, Mauro; Gandolfi, Remo; Sarzi-Amade, Mirko, Journal of the Chemical Society. Perkin Transactions 2 (2001), 1998, # 11, p. 2413 - 2419
作者:Freccero, Mauro、Gandolfi, Remo、Sarzi-Amade, Mirko、Rastelli, Augusto
DOI:——
日期:——
Cyclobutene photochemistry. Nonstereospecific photochemical ring opening of simple cyclobutenes
作者:K. Brady Clark、William J. Leigh
DOI:10.1021/ja00254a030
日期:1987.9
The photochemistry of bicyclo(3.2.0)hept-6-ene, bicyclo(4.2.0)oct-7-ene, and cis- and trans-3,4-dimethylcyclobutene has been investigated in hydrocarbon solution with monochromatic far-ultraviolet (185 and 193 nm) light sources. All of these simple cyclobutene derivatives undergo ring opening to yield the isomeric 1,3-dienes, and the latter three open nonstereospecifically to yield mixtures of the
研究了双环(3.2.0)庚-6-烯、双环(4.2.0)辛-7-烯和顺式和反式-3,4-二甲基环丁烯在具有单色远紫外光的烃溶液中的光化学( 185 和 193 nm) 光源。所有这些简单的环丁烯衍生物都进行开环以产生异构的 1,3-二烯,后三种以非立体有择的方式打开以产生可能的几何异构体的混合物。异构的 3,4-二甲基环丁烯产生三种 2,4-己二烯异构体的不同混合物,并且在每种情况下,混合物被加权以有利于轨道对称性禁止异构体。已尝试在纯反旋转的背景下分析双环 (4.2.0) 辛烯和异构 3,4-二甲基环丁烯开环的相对异构二烯产率,最近的 ab initio 计算表明的绝热开环机制应该是可能的。虽然前一种化合物的结果与这种机制一致,但对后两种化合物光解产生的异构 2,4-己二烯的相对产率的分析表明,通过正式禁止的旋转途径进行的光化学开环可能在一定程度上竞争具有旋转环开口。