Chemo, regio, and stereoselective photo-oxygenations: Conformational and substituent effects, biomass valorization, and applications in photomicroreactors

该项目涉及新底物类别的开发，反应条件，微反应器设置，以及单线态氧光氧化过程的后续反应。我们希望研究构象控制对申克烯氧化中环己烯衍生物的反应活性和选择性的影响。结合合成、理论和操作的努力，将引入在温和条件下进行高选择性双氧化的新型环状己烯。机制研究将致力于双环烯烃和环烯基芳烃的取代基效应，以阐明构象应变和机制二分法。在还原剂、氧化剂、催化剂和亲核试剂的存在下，将研究所得到的烯丙基氢过氧化物的各种后续反应，以获得广泛的氧化平台分子的化学空间。与空气/氧气的连续光氧化为生物质化学物质的增值提供了很大尚未开发的潜力。我们将通过从腰果果废料中提取的腰果酚混合物的综合技术、分析和机理研究来证明这一概念。三种不同的“相”——液体、气体和光之间的反应通常具有较低的色散（混合、光衰减）。因此，我们将继续努力设计和建造新的模块化光反应器，用于与氧气/空气的光氧化，停留时间在几分钟范围内。

This project deals with the development of new substrate classes, reaction conditions, microreactor setups, and follow-up reactions of photooxygenation processes with singlet oxygen. We wish to study the effects of conformational control on the reactivity and selectivity of cyclohexene derivatives in Schenck-ene oxidations. A combined synthetic, theoretical, and operational effort will introduce new anellated cyclohexenes that engage in highly selective dioxygenation under mild conditions. Mechanistic studies will be devoted to substituent effects in bicyclic alkenes and cycloalkenylarenes to elucidate conformational strain and mechanistic dichotomies. Various follow-up reactions of the resultant allylic hydroperoxides will be studied in the presence of reductants, oxidants, catalysts, and nucleophiles to access a wide chemical space of oxygenated platform molecules. Continuous photo-oxidations with air/oxygen offer largely untapped potential for the valorization of biomass chemicals. We will demonstrate this concept in a combined technical, analytical, and mechanistic study with cardanol mixtures from cashew nutshell waste. Reactions between the three distinct "phases" liquid, gas, and light generally suffer from low dispersion (mixing, light attenuation). We will therefore continue our ongoing efforts to design and construct new modular photoreactors for applications to photooxygenations with oxygen/air with residence times in the few min range.