Yuan-Qing Tang, I. Sattler, R. Thiericke
2001
Citations
0
Influential Citations
123
Citations
Quality indicators
Journal
European Journal of Organic Chemistry
Abstract
New diketopiperazines, named maremycins C1/C2 (1a/1b) and D1/D2 (2a/2b), as well as the novel spiro-indoles, maremycins E (3) and F (4), have been detected alongside the known maremycin B (6) in the culture broth of Streptomyces sp. (strain GT 051237) by chemical screening. The structures have been determined by detailed NMR spectroscopic investigations of the isolated metabolites. Maremycins C1/C2 (1a/1b) as well as D1/D2 (2a/2b) are diastereomers and were identified as mixtures. Structurally, maremycins C1/C2 (1a/1b) are the diastereomers of the sulfur oxidation products of maremycin B (6), while D1/D2 (2a/2b) are the demethylmercapto analogues of maremycins A (5) and B (6), respectively. Maremycins E and F possess a novel structural skeleton, where a spiro moiety is formed between the 6-position of the cyclopenta[f]quinoxaline moiety and the 3′-position of the indol-2-one moiety of the initial diketopiperazine product.