RESUMO
The sigma-enynyl complex [TpRu(C(Ph)=C(Ph)C identical to CPh)(P-MeiPr2)] efficiently catalyses the regioselective cyclization of alpha,omega-alkynoic acids to yield endocyclic enol lactones having ring size up to 12 atoms.
Assuntos
Lactonas/síntese química , Alcinos , Ácidos Carboxílicos/química , Catálise , Ciclização , Lactonas/química , Compostos Organometálicos/química , Rutênio/químicaRESUMO
The synthesis of (+/-)-11alpha-hydroxy-3-oxo-6alphaH,7alphaH, 10betaMe-eudesman-1,2-4,5-dien-6,12-olide (1), previously isolated from Melanoselinum decipiens, is described, and its structure has been corrected.
Assuntos
Apiaceae/química , Lactonas/síntese química , Sesquiterpenos de Eudesmano , Sesquiterpenos/síntese química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Análise EspectralRESUMO
The effect on germination, shoot, and root growth by bergapten, xanthotoxin, imperatorin, xanthyletin, xanthoxyletin, luvangetin, donatin and alloxanthoxyletol fromPilocarpus goudotianus leaves, onLactuca sativa var. nigra seedlings has been evaluated. A structure-activity correlation is discussed based on the bioassay results. Furanocoumarins appear to be the most active compounds in comparison with pyrano- and simple coumarins. The presence of an oxygenated function at C-8 decreases the germination effect in furano- and pyranocoumarins, while C-5 substituents do not cause significant changes on the activity.
RESUMO
The leaves of PILOCARPUS GOUDOTIANUS afforded in addition to eight known coumarins three new ones, donatin, alloxanthoxyletol, and (+)-elisin. The structures were elucidated on the basis of spectroscopic evidence and chemical derivatives.
RESUMO
13 C NMR data for several simple coumarins are reported. The γsyn effect of a 5-methoxy substituent on the C-4 chemical shift was observed and measured. The effects of an 8-iodo substituent on the chemical shifts of the carbons of the coumarinic skeleton are discussed.
