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-Oct-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
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