Synthesis of 1,4-Oxazepane-2,5-diones via Cyclization of Rotationally Restricted Amino Acid Precursors and Structural Reassignment of Serratin.
J Org Chem
; 82(12): 6210-6222, 2017 06 16.
Article
em En
| MEDLINE
| ID: mdl-28530397
ABSTRACT
Several natural products containing a 1,4-oxazepane-2,5-dione-core are known. One example is serratin, isolated from Serratia marcescens. Because of the presence of a carboxylic amide, which has a preference for a trans-conformation, and the presence of a labile lactone in this core, many synthetic methodologies commonly used for the cyclization toward medium-sized heterocycles cannot be applied. As N-acyl amino acids lacking a third substituent at nitrogen failed to undergo ring-closure, several N-protecting groups were evaluated. With the use of the removable PMB-group, an N-unsubstituted 1,4-oxazepane-2,5-dione was synthesized. Via the application of pseudoprolines (i.e. serine-derived oxazolidines as another type of protecting group), a compound with the presumed structure of the natural product serratin was obtained. As a result of the differences in spectral data, the incorrect structural assignment of the natural product serratin was identified. Instead of the predicted seven-membered heterocycle, a symmetrical serratamolide analogue is proposed to be the correct structure of serratin.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oxazepinas
/
Triterpenos
/
Aminoácidos
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article