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Synlett 1997; 1997(1): 111-114
DOI: 10.1055/s-1997-17828
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A New Versatile Reagent for the Synthesis of Cyclopropylamines Including 4-Azaspiro[2.n]alkanes and Bicyclo[n.1.0]alkylamines

Vladimir Chaplinski, Harald Winsel, Markus Kordes, Armin de Meijere*
  • *Institut für Organische Chemie, Georg-August-Universität Göttingen, Tammannstraße 2, D-37077 Göttingen, Germany
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Publication Date:
22 March 2004 (online)

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The reaction of dialkylcarboxamides 1 with 1 equiv. of methyltriisopropyloxytitanium together with only 1.1 equiv. of a Grignard reagent gives cyclopropylamines 3 in better yields than the previously published method with 2 equiv. of Grignard reagent and 1 equiv. of Ti(OiPr)4. This new protocol can be applied to intramolecular reactions with in situ generation of the Grignard reagent from ω-bromo-N,N-dimethylhexanamide and methyl ω-bromohexanoate yielding the expected 1-dimetehylaminocyclo[4.1.0]hexane 15 and the corresponding alcohol 18. Cyclohexylmagnesium bromide or chloride transforms N,N-dibenzylformamide and ethyl acetate to 7-exo-N,N-dibenzylaminonorcarane and 7-exo-hydroxy-7-methylnorcarane. N-Methyl-ℇ-caprolactam 25b and even the strained N-benzylpropiolactam 25a were converted to the spirocyclopropanated heterocycles 26a,b.

cyclopropylamines - substituted - bicyclic - functionalized - cyclopropanation - titanium mediated