Simple,Copper(I)-Catalyzed Oxidation of Benzylic/Allylic Alcohols to Carbonyl Compounds: Synthesis of Functionalized Cinnamates in One Pot

An environmentally benign [Cu(I)]-catalyzed oxidation of activated (benzylic/allylic) alcohols to the corresponding carbonyl compounds is presented. Interestingly, the reaction was also compatible with benzylic alcohols containing ortho-bromo substituents on the aromatic ring without competing with the expected intermolecular Buchwald coupling. Significantly, the catalytic system enables the synthesis of cinnamate-esters in a sequential domino one-pot fashion via oxidation followed by Wittig–Horner protocol.     

Ruthenium‐Catalyzed Oxidation of Alkenes,Alkynes, and Alcohols to Organic Acids with Aqueous Hydrogen Peroxide

A protocol that adopts aqueous hydrogen peroxide as a terminal oxidant and [(Me₃tacn)(CF₃CO₂)₂Ru^III(OH₂)]CF₃CO₂ ( 1 ; Me₃tacn=1,4,7‐trimethyl‐1,4,7‐triazacyclononane) as a catalyst for oxidation of alkenes, alkynes, and alcohols to organic acids in over 80 % yield is presented. For the oxidation of cyclohexene to adipic acid, the loading of 1 can be lowered to 0.1 mol %. On the one‐mole scale, the oxidation of cyclohexene, cyclooctene, and 1‐octanol with 1 mol % of 1 produced adipic acid (124 g, 85 % yield), suberic acid (158 g, 91 % yield), and 1‐octanoic acid (129 g, 90 % yield), respectively. The oxidative C?C bond‐cleavage reaction proceeded through the formation of cis‐ and trans‐diol intermediates, which were further oxidized to carboxylic acids via C? C bond cleavage.     

N-Methyl Piperidinium Chlorochromate Adsorbed on Alumina: A New and Selective Reagent for the Oxidation of Benzylic Alcohols to their Corresponding Carbonyl Compounds

Summary.  N-Methyl piperidinium chlorochromate adsorbed on alumina oxidizes a wide variety of benzylic alcohols to the corresponding carbonyl compounds. Received May 18, 2000. Accepted (revised) July 4, 2000     

醇类化合物气相色谱保留指数的分子拓扑研究

分子中原子i的特征值(ti)定义为tj＝1 ∑hi。并计算了醇类化合物的氢连接性指数，藉助多元线性回归技术分别建立了25个醇类化合物的指数与这些物质的气相色谱保留指数的定量结构／性质相关关系模型。模型具有良好的稳定性和预测能力，氢连接性指数能较好地反映化合物的结构特征。     

Hot Water‐Promoted SN1 Solvolysis Reactions of Allylic and Benzylic Alcohols

During the studies of hydrolysis of epoxides in water, we found that the hydrolysis of (?)‐α‐pinene oxide at 20 °C gave enantiomerically pure trans‐(?)‐sobrerol, whereas the same reaction in water heated at reflux unexpectedly gave a racemic mixture of trans‐ and cis‐sobrerol (trans/cis=6:4). We have examined this remarkable difference in detail and found that hot water, whose behavior is quite different compared with room‐ or high‐temperature water, could promote S_N1 solvolysis reactions of allylic alcohols and thus caused the racemization of trans‐(?)‐sobrerol. The effect of reaction temperature, the addition of organic co‐solvent, and the concentration of the solute on the rate of the racemization of trans‐(?)‐sobrerol were further examined to understand the role that hot water played in the reaction. It was proposed that the catalytic effects of hot water are owing to its mild acidic characteristic, thermal activation, high ionizing power, and better solubility of organic reactant. Further investigation showed that the racemization of other chiral allylic/benzylic alcohols could efficiently proceed in hot water.     

吖啶作为检测试剂脂肪醇和脂肪酸的间接光度高效液相色谱研究

以吖啶作为新型检测试剂,研究C_4～C_(12)脂肪醇、C_6～C_(16)脂肪酸的间接光度高效液相色谱,探讨影响色谱保留和产生间接光度响应的因素,从分离检测机理解释两类化合物色谱行为和检测响应的差别,提出新的分离测定脂肪醇和脂肪酸的间接光度高效液相色谱系统。     

A Simple and Versatile Re‐Catalyzed Meyer–Schuster Rearrangement of Propargylic Alcohols to α,β‐Unsaturated Carbonyl Compounds

Rhenium does the job! A readily available rhenium complex efficiently catalyzed the direct Meyer–Schuster‐like rearrangement of different alkyl‐ and aryl‐substituted propargylic secondary and tertiary alcohols to the corresponding α,β‐unsaturated compounds, which were produced with virtually complete E stereoselectivity. The reaction proceeded under neutral conditions and no racemization of potentially enolizable stereocenters was observed.

     

Selective Hydrogen Atom Abstraction through Induced Bond Polarization: Direct α‐Arylation of Alcohols through Photoredox,HAT, and Nickel Catalysis

The combination of nickel metallaphotoredox catalysis, hydrogen atom transfer catalysis, and a Lewis acid activation mode, has led to the development of an arylation method for the selective functionalization of alcohol α‐hydroxy C?H bonds. This approach employs zinc‐mediated alcohol deprotonation to activate α‐hydroxy C?H bonds while simultaneously suppressing C?O bond formation by inhibiting the formation of nickel alkoxide species. The use of Zn‐based Lewis acids also deactivates other hydridic bonds such as α‐amino and α‐oxy C?H bonds. This approach facilitates rapid access to benzylic alcohols, an important motif in drug discovery. A 3‐step synthesis of the drug Prozac exemplifies the utility of this new method.     

Gold(I)‐Assisted α‐Allylation of Enals and Enones with Alcohols

The intermolecular α‐allylation of enals and enones occurs by the condensation of variously substituted allenamides with allylic alcohols. Cooperative catalysis by [Au(ItBu)NTf₂] and AgNTf₂ enables the synthesis of a range of densely functionalized α‐allylated enals, enones, and acyl silanes in good yield under mild reaction conditions. DFT calculations support the role of an α‐gold(I) enal/enone as the active nucleophilic species.