High yielding selective access to spirocyclopropanated 5-oxopiperazine-2-carboxylates and 1,4-diazepane-2,5-diones from methyl 2-chloro-2-cyclopropylideneacetate
作者:Michael Limbach、Vadim S. Korotkov、Mazen Es-Sayed、Armin de Meijere
DOI:10.1039/b809174a
日期:——
The 2-spirocyclopropanated methyl 5-oxopiperazine-2-carboxylate 3 and the 3-spirocyclopropanated 6-chloro-1,4-diazepane-2,5-dione 4 could both be prepared at choice in 93 and 88% yield, respectively, from methyl 2-chloro-2-cyclopropylideneacetate (1) 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 10 containing a rigidified mimic of a tripeptide with a DGR motif. The overall yield of 11 after deprotection of 10 (a total of 13 steps in 8 distinct operations) was 30%.
2-螺环丙烷基甲基5-氧代哌嗪-2-羧酸酯3和3-螺环丙烷基6-氯-1,4-二氮杂环庚烷-2,5-二酮4都可以从甲基2-氯-2-环丙亚基乙酸酯(1)中制备,选择顺序为3-苄氧基丙胺的迈克尔加成、与N-Boc-甘氨酸的肽偶联、Boc基团的去除和环化,产率分别为93%和88%。通过苄氧基丙基侧链的转化、与N-Boc-(S)-天冬酰胺的肽偶联、脱保护和重复环化,得到八氢[2H]吡嗪并[1,2-a]吡嗪三酮骨架10,其中包含具有DGR基序的三肽的刚性模拟物。10脱保护后的11(共13步,8个不同的操作)的总产率为30%。