Current Organic Chemistry - Volume 10, Issue 13, 2006

This volume of Current Organic Chemistry is dedicated to the topic of the use of heterogeneous catalysts in organic synthesis. Catalysis, in general, plays a crucial and dominant role in chemistry, which may be best illustrated by the fact that about 90% of all the chemical processes applied in industry are catalytic transformations. Since the early 1990s, with the advent of green chemistry, there has been a strong driving force t Read More

The state of the art for the enantio-differentiating hydrogenation over an asymmetrically modified nickel catalyst is reviewed along with the background development of the catalyst. An enantioselectivity up to 98% was obtained for the hydrogenation of β-functionalized ketones. The durability of the enantioselectivity was significantly improved using an in-situ-modified nickel powder catalyst (80-90% enantioselectivity Read More

The manuscript gives an overview mainly on the results performed at the Department of Organic Chemistry the University of Szeged on the enantioselective hydrogenation of activated ketones of various structures on Pt/alumina catalysts modified with cinchona alkaloids. Relevant results by other research groups are also referred too. The review covers the literature till the end of 2004.

The heterogeneous catalytic asymmetric hydrogenation of the C=C bond resulting in optically active product has been a challenge since decades. Such products can arise in enantio- and in diastereoselective reactions depending on whether the prochiral compound is hydrogenated with a chirally modified catalyst or the substrate itself contains the source of chirality in the form of a chiral moiety. The common step in these Read More

The review reports the general approach, problems, potential and recent advances in heterogeneously catalyzed Heck reactions. It demonstrates the advantages and limitations for practical applications at present. A literature overview is given separately for substrates that are easier to activate (aryl iodides, activated aryl bromides) and for non-/deactivated aryl bromides and aryl chlorides during the period between 200 Read More

Zeolite catalysts can play an important role in the development of greener organic syntheses through their abilities to act as heterogeneous catalysts, support reagents, entrain by-products, avoid aqueous work-ups and enhance product selectivities via shape-selectivity. We have shown that zeolites under modest conditions can have advantages in para-regioselective nitration, alkylation, acylation, methanesulfonylation a Read More

The basic and catalytic properties of hydrotalcites, supported fluorides and mixed oxides are reviewed, with a special emphasis on C-C bond forming reactions. Relatively strong basicity can be induced on hydrotalcites by calcination followed by rehydration. In that case the shift from Lewis to Bronsted basicity has strong influence on the catalytic properties. The basicity is further enhanced by introduction of t-butoxide Read More

The Meerwein-Ponndorf-Verley (MPV) transfer hydrogenation of aldehydes and ketones to the corresponding alcohols is distinguished by its exceptional chemoselectivity. This reaction is particularly suited for the reduction of unsaturated aldehydes and ketones, compared to catalytic reductions with molecular hydrogen using noble metal catalysts. The MPV reaction has traditionally been carried out using homogeneou Read More

The preparation and application of heterogenized metal complexes is a relatively new field of research resulting in a new way of catalysis, that we cannot realize either with traditional homogeneous or heterogeneous catalysts. The heterogenized metal complexes can successfully combine the excellent performance (high activity and selectivity) of homogeneous catalysts with the easy separation and recycling of the heterogene Read More

Supported liquid phase catalyst (SLPC) is one of effectively heterogenized homogeneous catalysts using organometallic complexes as active components, which are dissolved in a small quantity of liquid phase dispersed in the form of isle or film on the surface of supports. The SLPC has successfully been applied for several chemical transformations and this article will review recent results with respect to the preparation Read More

The methods to prepare mesoporous silica materials and their derivatization by catalytically active functional groups covalently anchored to the surface are summarized. A short description of the major characterization techniques is also given. The transformations induced by solids with anchored basic functions mainly with various amino groups including oxidations, C-C forming reactions, and enantioselective alkylations Read More