The base-promoted α-alkylation of N-((S)-1-arylethyl)azetidine-2-carbonitriles 3via formation of their N-borane complexes 4 was investigated. For example, treatment of diastereomerically pure borane N-((S)-1'-(4''-methoxyphenyl)ethyl)azetidine-2-carbonitrile complex (1S,2S,1'S)-4b with 1.2 equivalents of LDA at -78 °C followed by 1.3 equivalents of benzyl bromide at -78 °C and warming to room temperature produced α-benzylated (2S,1'S)-5ba in 72% yield and (2R,1'S)-5ba in 2% yield. A mechanism for this diastereoselective α-alkylation was proposed. Our method enables the production of optically active 2-substituted azetidine-2-carbonitriles, such as α-benzylated (S)-10a and (R)-10a, starting from commercially available (S)-(1-(4-methoxyphenyl)ethyl)amine.

中文翻译：

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通过 N-硼烷配合物的 α-烷基化，从手性 1-芳基乙胺合成光学活性 2-取代氮杂环丁烷-2-甲腈。


研究了 N-((S)-1-芳基乙基)氮杂环丁烷-2-甲腈 3 通过形成 N-硼烷配合物 4 的碱促进 α-烷基化反应。例如，在-78℃下用1.2当量的LDA处理非对映体纯硼烷N-((S)-1'-(4''-甲氧基苯基)乙基)氮杂环丁烷-2-甲腈络合物(1S,2S,1'S)-4b ℃，然后在-78℃加入1.3当量的苄基溴并升温至室温，产生α-苄基化(2S,1'S)-5ba，产率72%，(2R,1'S)-5ba，产率2%。提出了这种非对映选择性α-烷基化的机制。我们的方法能够从市售的 (S)-(1-(4-甲氧基苯基)) 开始生产光学活性 2-取代氮杂环丁烷-2-甲腈，例如 α-苄基化 (S)-10a 和 (R)-10a乙）胺。