RESUMO
[reaction: see text] The effect of chiral substituents on the enamide nitrogen atom upon the diastereoselection of the Mn(III)-mediated 4-exo-trig cyclization to beta-lactams was studied. A significant level of diastereoselectivity was achieved when an amino acid ester moiety was included into the enamidic skeleton. The structure of the major diastereoisomer was suggested by semiempirical calculations.
RESUMO
A study was carried out on 50 workers in a floriculture centre to evaluate the incidence of contact dermatitis to Alstroemeria. 3 subjects gave positive reactions to aqueous and ethanolic extracts of cut flowers, stems and leaves. By column chromatography, the allergen was isolated and its chemical structure identified as 6-tuliposide A by proton magnetic resonance and carbon-13 magnetic resonance. Only 6-tuliposide A was isolated from cut flowers, and this gave positive reactions when patch tested at 0.01%; a-methylene-gamma-butyrolactone at 10(-5) (v/v) was positive in the same 3 subjects. Other lactones (gamma-methylene-gamma-butyrolactone, alantolactone, isoalantolactone) were negative at all concentrations used.
Assuntos
Alérgenos/toxicidade , Dermatite Ocupacional/induzido quimicamente , Glicosídeos/toxicidade , Hidroxibutiratos/toxicidade , Extratos Vegetais/toxicidade , Plantas , Oxibato de Sódio/toxicidade , Adulto , Alérgenos/isolamento & purificação , Cromatografia em Camada Fina , Feminino , Glicosídeos/isolamento & purificação , Humanos , Masculino , Pessoa de Meia-Idade , Testes Cutâneos , Oxibato de Sódio/análogos & derivados , Oxibato de Sódio/isolamento & purificaçãoRESUMO
From the aerial part of Verbascum sinuatum L. a new iridoid diglycoside III has been isolated and its structure elucidated as 6-0-alphaL-rhamnopyranosylaucubin.