標題: | Face selectivity in the reactions of 2,4-disubstituted adamantanes and their modification by inclusion in beta-cyclodextrin solutions |
作者: | Chu, JH Li, WS Chao, I Chung, WS 應用化學系 Department of Applied Chemistry |
關鍵字: | face selectivity;2,4-disubstituted adamantanes;beta-cyclodextrin;inclusion complex;neighboring group participation |
公開日期: | 11-十月-2004 |
摘要: | Sodium borohydride reduction reactions on 4-X-adamantan-2-ones (where X=ethyleneketal 11, ethylenethioketal 12, and methylene 15) were studied, which gave Z-alcohols 16 and 17 (from en-face attack) as the predominant products for ketones 11 and 12, but gave 1: 1 mixture of Z- and E-18 alcohols for ketone 15. The en/zu face selectivity of 15 in sodium borohydride reduction was enhanced to 32/68 in beta-CD solution. Both 1,3-dipolar addition and dichlorocarbene addition reactions on 4-ethyleneketal-2-methyleneadamantane 13 underwent again predominant en-face attack to give products in an E/Z ratio of > 99:1 and 92:8, respectively. The exceptional high zu-face selectivity on the dichlorocarbene addition reaction of 15 may be explained by a temporal complexation between the carbene and the C-4-oxo group. In the epoxidation reaction of 13 and 15 the zu-face attack products were favored despite their steric congestions suggesting that hydrogen bonding interaction between the peroxide reagent and the C-4-oxo or 4-ethyleneketal is involved. (C) 2004 Elsevier Ltd. All rights reserved. |
URI: | http://dx.doi.org/10.1016/j.tet.2004.07.075 http://hdl.handle.net/11536/25764 |
ISSN: | 0040-4020 |
DOI: | 10.1016/j.tet.2004.07.075 |
期刊: | TETRAHEDRON |
Volume: | 60 |
Issue: | 42 |
起始頁: | 9493 |
結束頁: | 9501 |
顯示於類別: | 期刊論文 |