ルテニウムとキラルリン酸触媒を用いたアルデヒドと1,1-ディオルルアルク3エンのアンチ-1,2-オクサボリナン3エンのエナントオセレクティブ合成
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PubMedで要約を見る
まとめ
この要約は機械生成です。この研究では,ルテニウムとリン酸を用いたキラルホモアリルアルコールを合成するための新しい触媒法が導入されました. このプロセスは効率的に (Z) - ビニルボロナート化合物を生成し,さらなる合成修正を可能にします.
科学分野
- 有機化学
- カタリシス
- 合成方法論
背景
- 移行金属の触媒は現代の有機合成に不可欠です
- キラルリン酸は,非対称的変換の効果的な触媒である.
- ビニルボロナートは多用途の合成中間物質である.
研究 の 目的
- 同性アルコールのエナチオ選択的合成のための新しい触媒システムを開発する.
- 二重結合の転置とアリレーション反応を連続的に利用する.
- 合成用途のために (Z) - ビニルボロナート分子を組み込む.
主な方法
- ダブルボンドの転置のためのカチオンのルテニウム (II) 複合体を用いた触媒.
- キラルリン酸はアルデヒドのエナチオセレクティブ・アリレーションを触媒化した.
- ビニルボロナート中間物質のインシット生成と反応
主要な成果
- ルーテニウム触媒による1,1-二酸化ボリルアルク-2-エンの効率的な合成.
- 1,2-アンチステレオ化学によるホモアリルアルコールのエナチオ選択的形成.
- 1,2-オキシボリナン-3-エンのサイクルを容易にする (Z) -ビニルボロナート部分の設置.
結論
- 複雑なキラル分子を作る 強力な触媒戦略です
- 開発された方法は,有価な (Z) - ビニルボラネートを含む化合物へのアクセスを提供します.
- その結果生成される1,2-オキシボリナン-3-エンは,その後の合成処理のためのプラットフォームとして機能する.
関連する概念動画
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
Syn Dihydroxylation Mechanism
The reaction comprises a two-step mechanism. It begins with the addition of osmium tetroxide across the alkene double bond in a concerted manner forming a...
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
Borane as a reagent is very reactive, as the...
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
The observed...
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
The observed regioselectivity can be explained based on the radical stability and steric effect. From the radical stability perspective, adding hydrogen bromide in the presence of peroxide directs the bromine radical at the less substituted carbon via a more stable tertiary radical intermediate. Similarly, in the steric framework, the...
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Mechanism
The hydroboration-oxidation reaction is a two-step...