金属锌在有机合成反应中的应用

综述了近年来以金属锌作为还原剂的各种反应，以及它在有机合成中的应用。 讨论了金属锌在催化剂的作用下，还原碳碳、碳氮、碳氧重键及碳氧、碳硫、碳卤 等单键的还原和偶联。     

Cu（OAc）2/Pyrimidines-Catalyzed Cross-coupling Reactions of Aryl Iodides and Activated Aryl Bromides with Alkynes under Aerobic, Solvent-free and Palladium-free Conditions

Excellent results have been achieved in the Cu（OAc）2-catalyzed Sonogashira cross-couplings of aryl iodides and activated aryl bromides utilizing TBAF （tetrabutylammonium fluoride） as the base and 4,6-dimethoxypyrimidin-2-amine as the ligand. It is noteworthy that the reaction is conducted under aerobic, solvent-free and palladium-free conditions.     

Ni2+在γ-Al2O3上的分散状态及负载型Ni/γ-Al2O3催化剂的α-蒎烯加氢活性

用X-射线衍射(XRD)、紫外-可见漫散射光谱(UV-Vis DRS)、程序升温还原(TPR)、CO化学吸附和微反测试等方法研究了Ni²⁺在γ-Al₂O₃上的分散状态和负载型Ni/γ-Al₂O₃催化剂的α-蒎烯加氢催化活性。结果表明，当Ni²⁺负载量远低于其在γ-Al₂O₃载体表面分散容量时，Ni²⁺优先嵌入载体表面四面体空位，随着Ni²⁺负载量的增加，嵌入载体表面八面体空位Ni²⁺的比例增大。由于八面体Ni²⁺易被还原为金属态Ni⁰，NiO/γ-Al₂O₃样品的还原度随Ni²⁺负载量的增加而大幅度地增加，经氢还原所得Ni/γ-Al₂O₃催化剂的CO吸附量和α-蒎烯加氢催化活性大幅度增加。对La₂O₃助剂的作用进行了研究，结果表明分散在γ-Al₂O₃上的La³⁺物种可阻止Ni²⁺嵌入γ-Al₂O₃表面四面体空位，增大了八面体Ni²⁺物种所占比例，提高了催化剂的还原度，故Ni-La₂O₃/γ-Al₂O₃催化剂催化活性高于Ni/γ-Al₂O₃催化剂。     

Nb2O5/TiO2催化剂表面铌氧物种的分散状态和催化性能

用X射线粉末衍射(XRO)、拉曼光谱(LRS)、Hammett指示剂和微反测试等方法考察了负载型Nb2O5/TiO2催化剂表面铌氧(NbOx)物种的分散状态、表面酸性和催化异丁烯(IB)与异丁醛(IBA)缩合生成2，5-二甲基．2，4．己二烯(DMHD)反应的催化性能．实验测得Nb2O5在TiO2表面的分散容量为0．94mmol／100m^2TiO2，与“嵌入模型”理论计算值相近．当负载量低于分散容量的1／3时，Nb2O5主要以孤立的NbOx物种通过Nb—O—Ti链与载体表面相连，这种孤立的NbOx物种酸性很弱，催化活性很低．随负载量的增加，孤立的NbOx物种通过Nb—O—Nb键连接聚合，表面酸性增强，IB与IBA缩合生成DMHD的转化数(TON)增加．当Nb2O5负载量超过分散容量时，表面NbOx物种主要是通过Nb—O—Nb化学键相连形成多层的Nb2O5虽然催化剂的强酸中心数量有所增加，但NbOx物种表面利用率下降，催化活性增加幅度趋缓．     

Ni(II)-catalyzed Conia-ene reaction of 1,3-dicarbonyl compounds with alkynes

[reaction: see text]. We have discovered a Ni(II)-catalyzed Conia-ene reaction of 1,3-dicarbonyl compounds with alkynes. In the presence of Ni(acac)2 and Yb(OTf)3, various acetylenic 1,3-dicarbonyl compounds underwent Conia-ene reaction to give mono- and bicyclic olefinic cyclopentanes. A mechanism involving the enol-yne-Ni complex formation is proposed and supported by deuterium-labeling experiments.     

Efficient Stille cross-coupling reaction catalyzed by the Pd(OAc)2/Dabco catalytic system

[reaction: see text] An efficient Pd(OAc)2/Dabco-catalyzed Stille cross-coupling reaction procedure has been developed. In the presence of Pd(OAc)2 and Dabco (triethylenediamine), various aryl halides including aryl iodides, aryl bromides, and activated aryl chlorides were coupled efficiently with organotin compounds to afford the corresponding biaryls, alkene, and alkynes in good to excellent yields. Furthermore, high TONs [turnover numbers, up to 980,000 TONs for the coupling reaction of 1-bromo-4-nitrobenzene and furan-2-yltributyltin] for the Stille cross-coupling reaction were observed.     

Recyclable and reusable Pd(OAc)2/DABCO/PEG-400 system for Suzuki-Miyaura cross-coupling reaction

[reaction: see text] A stable and efficient Pd(OAc)2/DABCO (triethylenediamine) catalytic system for Suzuki-Miyaura cross-coupling reaction has been developed. In the presence of Pd(OAc)2 and DABCO, coupling of aryl halides with arylboronic acids was carried out smoothly to afford good to excellent yields and high turnover numbers (TONs) (the maximal TONs were up to 960,000 for the reaction of 1-iodo-4-nitrobenzene with phenylboronic acid) using PEG-400 as the solvent. Moreover, the Pd(OAc)2/DABCO/PEG-400 system could be recycled and reused five times without any loss of catalytic activity for aryl iodides and bromides.     

PEG-400 promoted Pd(OAc)2/DABCO-catalyzed cross-coupling reactions in aqueous media

PEG-400 [poly(ethylene glycol-400)] was found to improve the Pd(OAc)₂/DABCO-catalyzed aqueous Suzuki-Miyaura and Stille cross-coupling reactions. In the presence of Pd(OAc)₂, DABCO, and PEG-400, a variety of aryl halides were coupled with arylboronic acids or organotin compounds efficiently to afford the corresponding cross-coupled products in moderate to excellent yields. The turnover numbers was up to 900,000 for the Suzuki-Miyaura reaction and up to 9800 for the Stille reaction. The catalyst system was also effective for Heck and Sonogashira cross-coupling reactions to some extent.     

Where is the road to bio-water-saving for the globe?

The First International Conference on the Theory and Practices in Bio-water-saving (ICTPB) was held from May 21 to 25, 2006 in Beijing, China. This indicated that the work related to this hot topic on the globe has been paid more attention to. Most progress in this field has been presented from near 300 participating people worldwide, who were meeting together to discuss about the theory and practices of water-saving biology and how to serve global agricultural and ecological sustainable development. The work related to bio-water-saving has been involved in different scales and soil–plant root biointerfaces. On the basis of this background and in combination with the work from our laboratory and the center, we provided some ideas for global bio-water-saving in this paper, sharing the achievement in this field and advocating true bio-water-saving for the world and promoting the pace of global bio-water-saving.     

Reusable Cu2O/PPh3/TBAB system for the cross-couplings of aryl halides and heteroaryl halides with terminal alkynes

An efficient and reusable Cu2O/PPh3/TBAB (n-Bu4NBr) system for the cross-coupling reactions of aryl and heteroaryl halides with terminal alkynes has been developed. Four types of Cu2O, including bulky Cu2O, cubic Cu2O nanoparticles, octahedral Cu2O nanoparticles, and spherical Cu2O nanoparticles, were examined, and the octahedral Cu2O nanoparticles were found to be the most effective catalyst for the reaction. In the presence of the octahedral Cu2O nanoparticles, PPh3, and TBAB, a variety of aryl and heteroaryl halides were reacted with alkynes including alkynols smoothly in moderate to good yields. Noteworthy is that the Cu2O/PPh3/TBAB system can be recovered and reused several times without loss of any activities.