cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system’s exceptional siteselectivity and functional group
脂肪族催化脱氢 (CDA) 在有机合成中的价值在很大程度上仍未得到充分探索。已知的均相 CDA 系统通常需要使用牺牲氢受体(或氧化剂)、贵金属催化剂和苛刻的反应条件,因此将大多数现有方法限制为非或低官能化烷烃的脱氢。在这里,我们描述了一种可见光驱动的双催化剂系统,该系统由廉价的有机光氧化还原和贱金属催化剂组成,用于室温、无受体 CDA (Al-CDA)。该过程由光激发的 2-氯蒽醌引发,涉及脂肪族的 H 原子转移 (HAT) 形成烷基自由基,然后与钴肟反应生成烯烃和 H 2. 这种操作简单的方法能够将容易获得的化学原料直接脱氢成多种官能化的烯烃。例如,我们首次证明了硫醚和酰胺在无氧化剂条件下分别脱饱和为烯基硫醚和烯酰胺。此外,14 种生物相关分子和药物成分的后期脱氢和合成说明了该系统卓越的位点选择性和官能团耐受性。机理研究揭示了双重 HAT 过程,并提供了对反应性和位点选择性起源的见解。
Ligand‐Controlled C−O Bond Coupling of Carboxylic Acids and Aryl Iodides: Experimental and Computational Insights
Palladium‐catalyzedcross‐coupling reactions between carboxylic acids and arylhalides have several possible competitive pathways. Decarboxylative C−C bond coupling and C−H arylation are well established in the literature. However, direct C−O bond coupling between carboxylic acids and arylhalides has received little success. In this report, we describe a protocol for exclusive C−O bond formation,
Water-Soluble Acylating Agents: Preparation of 2-Acylthio-1-alkylpyridinium Salts and Acylation of Phenols, Acids, and/or Amines with These Salts in an Aqueous Phase
Reaction of phenols, amines, and acids with 2-benzoylthio-1-methylpyridiniumchloride prepared in situ from benzoyl chloride and 1-methyl-2(1H)-pyridinethione, afforded the corresponding benzoyl derivatives in good yields. In the reaction of p-nitrophenol, even a catalytic amount of 1-methyl-2(1H)-pyridinethione proved to be effective. Similar reactions of p-nitrophenol with isobutyryl chloride and acetyl
Dibenzoylmethane sunscreens photostabilized with arylalkyl amide or ester compounds
申请人:Candau Didier
公开号:US20080019930A1
公开(公告)日:2008-01-24
Improvedly effective and photostable sunscreen compositions combine a dibenzoylmethane screening agent and a specific arylalkyl amide or ester compound of the following formulae (I), (II) or (III):