Photochemische Reaktionen. 86. Mitteilung [1]. Zur Photolyse von Bicyclo[3.3.1]nonan-2-on
作者:Rudolf Otto Duthaler、Regula Susanna Stingelin-Schmid、Camille Ganter
DOI:10.1002/hlca.19760590136
日期:——
Photolysis of Bicyclo[3.3.1]nonan-2-one.
双环[3.3.1]壬二-2-酮的光解。
Stereocontrolled Preparation of Spirocyclic Ethers by Intramolecular Trapping of Oxonium Ions with Allylsilanes
作者:Leo A. Paquette、Jinsung Tae
DOI:10.1021/jo961306k
日期:1996.1.1
6-dimethyl derivative, the substituents act in a reinforcing manner and direct cyclization uniquely in one direction. Both the cis and trans bicyclic ethers ring close on that pi-surface of the intermediate oxoniumion syn to the angular hydrogen. The results are rationalized in terms of the predilection of the associated oxoniumions for nucleophilic capture via a chairlike or twist-boat transition state
已经研究了在各个环位置被烷基取代的2-(苯磺酰基)-2-(4-(((三甲基甲硅烷基)甲基)-4-戊烯基)四氢吡喃自发分子内环化的立体选择性。对于4-和6-甲基衍生物,螺环中心的形成仅与甲基相反。5-甲基实例的结果是3.7:1 syn / anti拆分。对于反式4,6-二甲基衍生物,取代基以增强方式起作用,并且在一个方向上唯一地直接环化。顺式和反式双环醚均在中间体氧鎓离子的pi表面上与角氢同位而闭合。根据相关联的氧鎓离子的偏爱,可以通过椅子状或扭曲舟状过渡态进行亲核捕获,从而使结果合理化。
An unusual reaction of cyclic enol ethers with titanium(III) tetrahydroborate
作者:K.S. Ravikumar、Srinivasan Chandrasekaran
DOI:10.1016/s0040-4020(96)01176-3
日期:1997.2
Titanium(III) Tetrahydroborate formed in situ from titanium tetrachloride and benzyltrieihylammonium retrahydroborate (1:4) readily reacts with cyclic enol ethers in dichloromethane at -20 degrees C to give the corresponding acyclic diols in high yields after simple aqueous work-up. (C) 1997 Elsevier Science Ltd.
A Ring Size-Selective Reduction of Lactones Using SmI<sub>2</sub> and H<sub>2</sub>O
作者:Lorna A. Duffy、Hiroshi Matsubara、David J. Procter
DOI:10.1021/ja078137d
日期:2008.1.30
The Sml(2)-H2O reducing systems shows complete selectivity for six-membered lactones over other classes of lactone and esters. Experimental and computational studies suggest that the origin of the selectivity lies in the initial electron-transfer to the lactone carbonyl.