低電圧トングステン触媒は,非活性アルケンのサイト選択的同位体化-水酸化を可能にします
Tanner C Jankins1, Raul Martin-Montero2, Phillippa Cooper1
1Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.
Journal of the American Chemical Society
|September 9, 2021
まとめ
トングステン触媒は,ディスタルC−H結合における非活性化アルケンの水酸化を誘導基を用いて可能にします. このシンプルで選択的な方法は,ボリレーション反応のための新しいサイト選択性パターンを提供します.
科学分野:
- 有機金属化学
- キャタリシス
- 有機合成
背景:
- ハイドロボレーションは有機合成における重要な変換です
- グループ戦略の指示は,サイト選択的なC-H機能化に不可欠です.
- 活性化されていないC−H結合を機能化するための触媒的方法は依然として困難である.
研究 の 目的:
- 活性化されていないアルケンの新型タングステン触媒水酸化を開発する.
- ディスタルC ((sp3) -H結合で選択的機能化を達成する.
- この変革におけるネイティブ・ディレクター集団の有用性を探求する.
主な方法:
- トングステン触媒による水酸化反応
- ネイティブ・ディレクティング・グループを持つ未活性化アルケンを利用した.
- 最適な収量と選択性のための反応条件を調査した.
主要な成果:
- 非活性化アルケンの遠隔C ((sp3) -H結合の水酸化を達成した.
- 高い地域と化学的選択性を示した.
- 開発されたメソッドの広範囲の基板を展示しました.
結論:
- 開発されたボルンガム催化方法は,水酸化アルケンの単純な選択的経路を提供します.
- このアプローチは,既存のボリレーション反応と比較して補完的なサイト選択性パターンを提供します.
- この方法論は,C-H機能化とアルケンの非機能化のためのツールキットを拡張します.
関連する概念動画
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
8.3K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
8.3K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
19.3K
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.
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.
19.3K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.5K
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...
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...
3.5K
02:36Regioselectivity and Stereochemistry of Hydroboration
8.6K
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...
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...
8.6K
02:13Reduction of Alkenes: Catalytic Hydrogenation
12.8K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
12.8K
03:08Hydroboration-Oxidation of Alkenes
9.4K
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.
9.4K