A New Versatile Reagent for the Synthesis of Cyclopropylamines Including 4-Azaspiro[2.n]alkanes and Bicyclo[n.1.0]alkylamines
作者:Vladimir Chaplinski、Harald Winsel、Markus Kordes、Armin de Meijere
DOI:10.1055/s-1997-17828
日期:——
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 Ï-bromo-N,N-dimethylhexanamide and methyl Ï-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-â-caprolactam 25b and even the strained N-benzylpropiolactam 25a were converted to the spirocyclopropanated heterocycles 26a,b.
二烷基羧酰胺1与等摩尔的三异丙氧甲基钛反应,结合仅1.1摩尔的格氏试剂,所得环丙胺3的产率优于之前发布的方法,该方法使用2摩尔的格氏试剂和1摩尔的Ti(OiPr)4。这种新方案可用于酰胺内分子反应,通通过ω-溴-N,N-二甲基己酰胺和甲基ω-溴己酸酯原位生成格氏试剂,获得预期的1-二甲氨基环[4.1.0]己烷15及相应的醇18。环己基溴镁或氯镁可将N,N-二苯甲基甲酰胺和乙酸乙酯转化为7-exo-N,N-二苯甲基氨基诺卡烷和7-exo-羟基-7-甲基诺卡烷。N-甲基-ε-己内酯25b,甚至是应变较大的N-苄基丙烯内酯25a,均可转化为螺环丙烷化的杂环化合物26a,b。