Germacranolides of Erlangea cordifolia: structure and absolute stereochemistry of cordifene and cordifene 4β, 15-oxide by X-ray and spectrosopic methods
dc.contributor.author | Maradufu, Asafu | |
dc.contributor.author | Gatuma, Ambrose K | |
dc.contributor.author | Crombie, W Mary L | |
dc.contributor.author | Crombie, Leslie | |
dc.contributor.author | Begley, Michael J | |
dc.date.accessioned | 2013-07-11T07:04:51Z | |
dc.date.available | 2013-07-11T07:04:51Z | |
dc.date.issued | 1981 | |
dc.identifier.citation | Journal of the Chemical Society, Perkin Transactions 1 , 1981, 2702-2709 | en |
dc.identifier.uri | http://pubs.rsc.org/en/content/articlelanding/1981/p1/p19810002702 | |
dc.identifier.uri | http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/47286 | |
dc.description.abstract | 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. | en |
dc.language.iso | en | en |
dc.title | Germacranolides of Erlangea cordifolia: structure and absolute stereochemistry of cordifene and cordifene 4β, 15-oxide by X-ray and spectrosopic methods | en |
dc.type | Article | en |
local.publisher | Department of Pharmacology and Pharmacognosy | en |
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