Germacranolides of Erlangea cordifolia: structure and absolute stereochemistry of cordifene and cordifene 4β, 15-oxide by X-ray and spectrosopic methods
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Date
1981Author
Maradufu, Asafu
Gatuma, Ambrose K
Crombie, W Mary L
Crombie, Leslie
Begley, Michael J
Type
ArticleLanguage
enMetadata
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Cordifene and cordifene 4β,15-oxide, extracted from the insect-antifeedant plant Erlangea cordifolia, have been examined by spectroscopic and X-ray techniques. Cordifene is shown by X-ray analysis (R 5.49%) as its 5-bromo-2-furoate (3c) to be the 8-angelate ester of a 1R,2S,3S,5S,6S,7R,8S,10R-6,7-lactonised dihydroxygermacranolide bis-epoxide (3a). Cordifene 4β,15-oxide, having three contiguous epoxide groups and nine chiral centres, is the 4R-derivative (2a), as demonstrated by direct X-ray methods (R 3.2%): its abolute configuration is linked to (3a) by c.d. methods. On the basis of Stöcklin's rules, the signature of the n→π* c.d. maximum leads to an incorrect absolute configuration for both compounds, but the Beecham–McPhail treatment satisfactorily explains the situation. 1H N.m.r. data indicate that solution conformations are similar to crystal conformations.
URI
http://pubs.rsc.org/en/content/articlelanding/1981/p1/p19810002702http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/47286
Citation
Journal of the Chemical Society, Perkin Transactions 1 , 1981, 2702-2709Publisher
Department of Pharmacology and Pharmacognosy
Collections
- Faculty of Health Sciences (FHS) [10378]