純粋なH-メンチルフォスフィネートから大量に発生した,光学的に活性なP-ステロゲン型フォスフィンボラン
David Gatineau1, Laurent Giordano, Gérard Buono
1Equipe Chirosciences, UMR CNRS 6263-ISM2 Université Aix-Marseille III, Ecole Centrale de Marseille Av. Escadrille Normandie Niemen, 13397 Marseille Cedex 20, France.
Journal of the American Chemical Society
|June 18, 2011
まとめ
研究者らはメンチルフォスフィネートをキラルフォスフィンボランに変換し,高エナティオメール純度でボリュームの大きいP-ステロゲンフォスフィンボランの合成を可能にしました. この方法により,阻害された三次性フォスフィン-ボランと希少なエナティオプアフォスファパルダサイクルが得られました.
科学分野:
- オーガノフォスファルス 化学 化学
- アシンメトリック・シンセシス
- ステレオ化学 ステレオ化学
背景:
- キラル・フォスフィンは,非対称な触媒における重要なリガンドである.
- エナティオピュール・ボリュキ・フォスフィンを合成するための効率的な方法の開発は,依然として課題です.
研究 の 目的:
- 大量のP-ステロゲン二次および三次フォスフィン-ボランを合成するための新しい経路を開発する.
- これらのフォスフィン・ボランが,複雑なキラル・オーガノメタリック化合物を製造する際の有用性を実証する.
主な方法:
- 純粋なH-メンチルフォスフィナートからキラルフォスフィノ酸ボランに変換する.
- 二次および三次フォスフィン-ボランへの加工.
- 大量のオートリルフォスフィンを用いたフォスファルサイクルの合成.
主要な成果:
- 大量なP-ステロゲン二次フォスフィン-ボランを成功裏に製造した.
- 優れたエナティオメリック過剰を持つ多種多様な阻害されたP-キラル三次フォスフィン-ボランを合成しました.
- 希少なエナチオピュア・フォスファパルダサイクルの合成でその有用性を示した.
結論:
- 開発された方法は,価値あるキラル・フォスフィン・ボランの構成要素へのアクセスを提供します.
- 大容量のP-キラルフォスフィン-ボランは,複雑なキラル分子を構築するための効果的なリガンドです.
関連する概念動画
02:36Regioselectivity and Stereochemistry of Hydroboration
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.
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.
03:08Hydroboration-Oxidation of Alkenes
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.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
03:24Hybridization of Atomic Orbitals I
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
03:35Hybridization of Atomic Orbitals II
sp3d and sp3d 2 Hybridization
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.