Abstract
Naturally occurring nucleoside-peptide antibiotics such as muraymycins or caprazamycins are of major interest for the development of novel antibacterial agents. However, the synthesis of new analogues of these natural products for structure–activity relationship (SAR) studies is challenging. In our synthetic efforts towards a muraymycin-derived nucleoside building block suitable for attachment to a solid support, we came across an interesting side product. This compound resulted from an undesired Fmoc deprotection with subsequent cyclization, thus furnishing a remarkable caprazamycin-like seven-membered diazepanone ring.
Highlights
The encountered side reaction from precursor 4 to diazepanone 6 is highly interesting as the construction of the diazepanone scaffold represents one of the main challenges in the total synthesis of caprazamycins and their analogues [18,19,21,22]
To the best of our knowledge, a simple thermally promoted nucleophilic attack of the linker unit to a 7 -carboxylic acid ester moiety has not been successfully explored for the diazepanone-forming step before
The good yields of 6 obtained from this reaction strongly suggest that it should be investigated for caprazamycin syntheses in a more systematic way in the future
Summary
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