非対称な合成のためのシンプルで一般的なキラルシリコンルイス酸:高度にエナチオセレクティブ [3+2] アシルヒドラゾン-エノルエーテルサイクロアディション
Seiji Shirakawa1, Pamela J Lombardi, James L Leighton
1Department of Chemistry, Columbia University, New York, New York 10027, USA.
Journal of the American Chemical Society
|July 14, 2005
まとめ
新種のキラルシランルイス酸は,高度に選択的な [3 + 2]サイクル添加反応を可能にします. この実用的な方法は,大規模でも優れた収穫量とエナチオセレクティビティを達成します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- アシンメトリック・シンセシス
背景:
- サイクル添加反応は有機合成において根本的な役割を果たします.
- エナンチオセレクティブ・メソッドの開発は,キラル分子を作る上で極めて重要です.
研究 の 目的:
- 新しい,高度にダイアステレオセレクティブおよびエナチオセレクティブ [3 + 2]サイクロアディション反応を記述する.
- 単純なキラルシランのルイス酸を触媒として利用する.
主な方法:
- チラルシランのルイス酸を用いて,アシルヒドラゾンとエノールエーテル間の [3 + 2] サイクル添加を媒介する.
- 実用性を評価するために,大規模な反応 (5gのヒドラゾン) を実行します.
主要な成果:
- サイクル添加反応で高いダイアステロ選択性とエナチオ選択性を達成した.
- 大規模再結晶化後に93%の収量と99%のエナティオメール過剰 (ee) で製品を取得しました.
- 段階的な反応機構と非対称誘導のモデルを支持する証拠を提供した.
結論:
- 記述された [3 + 2] サイクロアディションは,複雑な分子を合成するための非常に実用的で選択的な方法です.
- キラルシランのルイス酸は,ステレオ化学を効果的に制御し,非対称合成のための貴重なツールを提供します.
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