RESUMO
Polyamines are ubiquitously found in nature. In this paper, we disclose our iterative coupling strategy for the synthesis of a structurally defined polymer of 1,3-propanediamine, and the polymer can be used for the synthesis of both the initially proposed structure and the revised structure of protoaculeine B isolated from a marine sponge. We first attempted the synthesis of polyamines using "the Ns strategy" but found that a polyamine with eleven Ns groups has solubility problems. We then examined the versatility of the photoremovable NPEC protecting group in polyamine synthesis. Finally, the synthesis of a suitably protected 12-mer polyamine was achieved employing the NPEC group for the temporary protection of a terminal amino group.
RESUMO
By establishing the procedures for sequential deprotections, reaction monitoring, purification, and handling, for the first time, we achieved the total synthesis of the proposed structure for protoaculeine B (2), which is a highly hydrophilic and polycationic amino acid. The NMR and mass spectra and chemical reactivity of the synthetic sample differed from those of natural protoaculeine B, which indicates the necessity for revision of the originally reported structure.
Assuntos
Poríferos/química , Animais , Indóis/síntese química , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Estrutura Molecular , Poliaminas/síntese química , EstereoisomerismoRESUMO
A synthetic strategy for accessing protoaculeine B (1), the N-terminal amino acid of the highly modified peptide toxin aculeine, was developed via the synthesis of the fully protected natural homologue of 1 with a 12-mer poly(propanediamine). The synthesis of mono(propanediamine) analog 2, as well as core amino acid 3, was demonstrated by this strategy. New amino acid 3 induced convulsions in mice; however, compound 2 showed no such activity.
