RESUMO
[reaction: see text] A short synthesis of the C(11)N(5) oroidin derivatives is reported. The key step of the strategy is a one-pot oxidative bromine-mediated addition of protected guanidines to the N-acyl-1,2-dihydropyridines 9a-c. The new N-acyl-1,2-dihydropyridines were prepared directly from pyridine and pyrrole-2-carbonyl chloride by reduction with borohydride reagent in one step.
Assuntos
Imidazóis/síntese química , Piridinas/síntese química , Pirróis/síntese química , Catálise , Imidazóis/química , Indicadores e Reagentes , Biologia Marinha , Estrutura Molecular , Oxirredução , Piridinas/química , Pirróis/químicaRESUMO
[reaction: see text] A simple synthesis of the fused tetrahydro-imidazopyridine 13 was accomplished via selective addition of protected guanidine to N-carbomethoxy-1,2-dihydropyridine in the presence of bromine. Base-mediated semicleavage of the aminal gave 4-substituted 2-aminoimidazole 14. With this new method, natural marine metabolite 3-amino-1-(2-aminoimidazol-4-yl)-prop-1-ene (1) and derivatives may now be prepared from pyridine. Ab initio calculations of the energies of tautomers I-IV and deuteration experiments have provided insight into their reactivity.
RESUMO
A new spontaneous oxidative transformation of the associated pyrrole-proline-guanidine to the natural marine pyrrole 2-aminoimidazolinone derivative has been achieved. The sensitive reaction requires air oxygen and the N-acylation of proline by pyrrole-2-carboxylic acid. Proline metabolism and pyrrole 2-aminoimidazole secondary metabolites formation seem to be related and are utilized by sponges under stress conditions for their defense against predators. A plausible stress-induced oxidative chemical pathway that establishes dispacamide derivatives as the forerunners in the biogenetic synthesis of the key pyrrole 2-aminoimidazole oroidin is proposed. The mechanism of the reaction seems to be another development of the known luciferins' chemiluminescent reactions in bioluminescent marine organisms.
