Michael Limbach, V. Korotkov, M. Es-Sayed*
Sep 17, 2008
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0
Influential Citations
6
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Journal
Organic & biomolecular chemistry
Abstract
The 2-spirocyclopropanated methyl 5-oxopiperazine-2-carboxylate and the 3-spirocyclopropanated 6-chloro-1,4-diazepane-2,5-dione could both be prepared at choice in 93 and 88% yield, respectively, from methyl 2-chloro-2-cyclopropylideneacetate () in a sequence of Michael addition of 3-benzyloxypropylamine, peptide coupling with N-Boc-glycine, Boc-group removal and cyclization. Transformation of the benzyloxypropyl side chain, peptide coupling with N-Boc-(S)-asparagine, deprotection and repeated cyclization led to the octahydro[2H]pyrazino[1,2-a]pyrazinetrione scaffold containing a rigidified mimic of a tripeptide with a DGR motif. The overall yield of after deprotection of (a total of 13 steps in 8 distinct operations) was 30%.