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[摘要]：Copper-mediated cyclopropanation of 1,3-dialkyl-1,3-dihydroimidazol-2-ones with diazomethane and methyl diazoacetate yields 2,4-diazabicyclo[3.1.0]hexan-3-ones and the first diaza[4.3.1]propellane. The bicyclic system survives elevated temperatures and in strongly basic and acidic solutions, but drastic conditions cleave the (C-1) (C-6) bond affording 1,3-dihydroimidazol-2-ones. Catalytic hydrogenation removes N-benzyl groups and opens the (C-1) (C-6) bond. Lithium aluminium hydride reduces 2,4-dibenzyl-2,4-diazabicyclo[3.1.0]hexan-3-one to a bicyclic aminal. Acid-induced cleavage of its imidazolidine ring is followed by unexpected transformations that probably procede via an acyclic intermediate, which comprises an azomethine ylide and an iminium moiety. 1,3-Cyclization involving both functional groups leads to N,N'-dibenzyl-trans-1,2-cyclopropanediamine, while 1,5-cyclization gives rise to the formation of N-benzylpyrrole along with N-benzylamine. |
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