Face selectivity in the reactions of 2,4-disubstituted adamantanes and their modification by inclusion in β-cyclodextrin solutions

Jean Ho Chu, Wan Sheung Li, Ito Chao, Wen-Sheng Chung

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

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 β-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. Graphical Abstract.

Original languageEnglish
Pages (from-to)9493-9501
Number of pages9
JournalTetrahedron
Volume60
Issue number42
DOIs
StatePublished - 11 Oct 2004

Keywords

  • 2,4-Disubstituted adamantanes
  • Face selectivity
  • Inclusion complex
  • Neighboring group participation
  • β-Cyclodextrin

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