ピリジンからバイサイクルピラゾリンおよびピラゾールへの光化学的骨格編集
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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,ピリジンを金属や触媒なしでバイサイクルピラゾリンとピラゾールに変換する新しい光化学的方法が導入されています. この骨格の編集は 薬の発見のための 汎用的な後期修正を提供します
科学分野
- 有機化学
- 写真化学
- 薬剤化学
背景
- ピリジンは医薬品の常用基材ですが,その改変は困難です.
- ピリジン変換の既存の方法は,しばしば厳しい条件,金属,または特定の触媒を必要とします.
研究 の 目的
- ピリジンの骨格の編集のための効率的な1ポット光化学プロトコルを開発します.
- ピリジンを様々なバイサイクルピラゾリンとピラゾールに変換する.
- 薬の分子を後期的に改造するための方法を提供する.
主な方法
- 軽い条件下での光化学反応です.
- ピリジンの構造から選択的に炭素原子を除去する.
- ストップフローとフロー化学システムを用いたスケールアップ研究
- 制御実験とDFT計算を用いたメカニズム調査.
主要な成果
- ピリジンの様々なバイサイクルピラゾリンとピラゾールへの成功変換
- 金属フリー,触媒フリー,添加物フリー反応条件の実証
- 複雑な分子の末期機能化における多角的な応用
- ダイエルス・アルダーとヘックのような他の反応との統合が成功しました
結論
- 開発された光化学的骨格編集プロトコルは効率的で多用途です.
- この方法は,ピリジンを含む薬剤候補を改変するための便利なアプローチを提供します.
- このプロトコルは,産業用合成の広範な適用性と可能性を示しています.
関連する概念動画
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
Thermally-induced [2 + 2] cycloadditions are symmetry forbidden. This is because the ground state HOMO of one ethylene molecule and the LUMO of the other ethylene are out of phase, preventing a concerted suprafacial-suprafacial overlap.
Absorption...
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
Electrocyclic reactions are highly stereospecific. For a substituted polyene, the stereochemical outcome...
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
The feasibility of cycloaddition reactions under thermal and photochemical conditions can be...
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
Dienophiles with one or more electron-withdrawing substituents form stereochemically different products in which the substituents are oriented in an endo (towards) or exo (away) configuration relative to the double bond.
The endo isomer is formed faster and is the kinetic product. The exo isomer is more stable and is the thermodynamic...
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.