アシンメトリックな水素調製のための不動的ビスディアザフォスフォラン触媒
Tyler T Adint1, Clark R Landis
1Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison Wisconsin 53706, United States.
Journal of the American Chemical Society
|April 19, 2014
まとめ
ビス-3,4-ディアザフォスフォラン (BDP) から派生した不動的非対称水素形成触媒は,均質な触媒に匹敵する高い選択性と活性を示します. これらのリサイクル可能な触媒は,バッチシステムとフローシステムの両方で,最小限のロジウム浸出で優れた性能を提供します.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- グリーン・ケミストリー (Green Chemistry)
背景:
- 均質な触媒は,高い選択性を提供しますが,分離の課題があります.
- 触媒の固定化は,再利用性と持続可能性にとって極めて重要です.
- ビス-3,4-ディアザフォスフォラン (BDP) は,非対称な触媒における効果的なリガンドである.
研究 の 目的:
- イモビライズされた非対称性水酸化 (iAHF) 触媒の開発と評価.
- 固定されたBDP触媒の性能を同質の同位体と比較する.
- 固定型水酸化触媒のリサイクル可能性と浸出性を評価する.
主な方法:
- エナンチオプアビス-3,4-ディアザフォスフォラン (BDPs) がカーボキシル酸機能化経由でビーズとシリカの支柱に共性的に結合する.
- 固定された水素形成触媒の形成は,結合されたBDPをRh ((acac) ((CO) 2) に暴露することによって行われる.
- プロキラルアルケンの非対称的水酸化過程におけるバッチ・フロー条件下における触媒性能の評価.
主要な成果:
- テンタゲル樹脂の固定化された触媒は,均質な触媒と比べて高い地域選択性とエナチオ選択性を示した.
- 加熱剤の活性度は,負荷を考慮して修正され,同質な同類品の活性に近かった.
- バッチ・リアクターとフロー・リアクターの両方で,優れた再利用性と最小限のロジウム浸出が観察されました.
- シリカ結合の触媒は,エナチオセレクティブ性が低下した.
結論:
- 固定されたBDPベースの触媒は,高選択性と活性を提供して,非対称性のある水素形成に有効です.
- テンタゲルで支えられた触媒は,金属の浸出を最小限に抑えた均質なシステムに再生可能で持続可能な代替手段を提供します.
- シリカを支える触媒については,エナチオセレクティビティを改善するためにさらなる最適化が必要である.
さらに関連する動画
![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
関連する概念動画
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
2.6K
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...
2.6K
02:36Regioselectivity and Stereochemistry of Hydroboration
7.8K
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...
7.8K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
6.9K
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.
6.9K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
19.8K
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.
19.8K
03:08Hydroboration-Oxidation of Alkenes
10.1K
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.
10.1K
01:28Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
5.6K
Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take place easily. For example, in the reduction of stilbene, the benzene ring remains unaffected while the alkene bond gets reduced. Hydrogenation of an alkene double bond is exothermic and a favorable process. In contrast, to hydrogenate the first unsaturated bond of benzene, an energy input is needed; that is, the process is endothermic. This is...
5.6K