Remote Position Substituents as Modulators of Conformational and Reactive Properties of Quinones. Relevance of the / 详细信息    查看全文

• 作者：Guillermo Roura-Pé ; rez ; Beatriz Quir&oacute ; z ; Martha Aguilar-Martí ; nez ; Carlos Frontana ; Alejandro Solano ; Ignacio Gonzá ; lez ; José ; Antonio Bautista-Martí ; nez ; Jes&uacut
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：March 16, 2007
• 年：2007
• 卷：72
• 期：6
• 页码：1883 - 1894
• 全文大小：547K
• 年卷期：v.72,no.6(March 16, 2007)
• ISSN：1520-6904

文摘

Several studies have described that quinoid rings with electron-rich olefins at remote position experiencechanges in their redox potential. Since the original description of these changes, different approacheshave been developed to describe the properties of the binding sites of ubiquinones. The origin of thisphenomenon has been attributed to lateral chain flexibility and its effect on the recognition betweenproteins and substrates associated with their important biological activity. The use of electrochemical-electron spin resonance (EC-ESR) assays and theoretical calculations at MP2/6-31G(d,p) and MP2/6-31++G(d,p)//MP2/6-31G(d,p) levels of several conformers of perezone [(2-(1,5-dimethyl-4-hexenyl)-3-hydroxy-5-methyl-1,4-benzoquinone] established that a weak - interaction controls not only themolecular conformation but also its diffusion coefficient and electrochemical properties. An analogousinteraction can be suggested as the origin of similar properties of ubiquinone Q₁₀. The use of nuclearmagnetic resonance rendered, for the first time, direct evidence of the participation of different perezoneconformers in solution and explained the cycloaddition process observed when the aforementioned quinoneis heated to form pipitzols, sesquiterpenes with a cedrene skeleton. The fact that biological systems canmodulate the redox potential of this type of quinones depending on the conformer recognized by anenzyme during a biological transformation is of great relevance.