リチウム-ボリレーションによる非循環分子における複数の,連続した四極性ステレオセンターの構築
Charlotte G Watson1, Angelica Balanta, Tim G Elford
1School of Chemistry, University of Bristol , Cantock's Close, Bristol, BS8 1TS, U.K.
Journal of the American Chemical Society
|December 4, 2014
まとめ
混合ボランを用いた新しい方法により,隣接する四次元の立体性センターの合成が可能になり,障害のあるシステムにおける標準ボリレーションの限界を克服しました. この強力なアプローチは,高いステレオコントロールで複雑な炭素鎖を作り出します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- ステレオセレクティブ合成
背景:
- 炭酸塩リチエーションに続いてボリリエーションは,ボロン反応剤の同型化のための重要な方法である.
- この標準的な方法は,特に四次中心の構築において,ステリカルに阻害された基板で課題に直面します.
研究 の 目的:
- 障害のあるシステムにおける隣接する四次元のステレオジェニックセンターを合成するための堅牢な方法を開発する.
- 複雑な炭素鎖の構築において完全なステレオ制御を達成するために.
主な方法:
- 阻害された二次カルバメートのボリル化のために混合ボラン (tBuBMe2) を利用した.
- 連続的な同型化のためのワンポット手順を開発し,複数の隣接する四次中心の作成を可能にしました.
- クロラミン処理で生成ボランを三次性アルコールまたはC-三次性アミンに変換する.
- ステレオ選択性の起源を調査するために,計算手法を使用した.
主要な成果:
- 混合ボランを用いた完全なステレオ制御を持つ隣接する四次元のステレオジェニックセンターを合成し,標準のtBu-ボロンエステルの失敗を克服しました.
- 1つの鍋でプロセスを繰り返す能力を示し,複数の隣接する四極性ステレオジェニックセンターを持つ炭素鎖を生成しました.
- 計算分析によって確認されたように,メチル群の移動よりもアルキル群の移動に対して高い選択性を達成しました.
- 合成されたボランを有価な三次アルコールとC-三次アミンの機能に効率的に変換した.
結論:
- 混合ボランは,阻害された四次中心の立体選択的合成のために,標準的なボロンエステルに優れた代替品を提供します.
- 開発されたワンポット,マルチステッププロトコルは,複数のステレオセンターを持つ複雑なカーボン・スカファッドへの効率的なアクセスを提供します.
- 計算による洞察は,鍵となるアルキル移行ステップのメカニズムと選択性を明確にします.
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