Current Organic Chemistry - Volume 14, Issue 3, 2010

This review deals with recent advances in ligand design for the intermolecular asymmetric Mizoroki-Heck reaction. Since the seminal report by Hayashi and co-workers in 1991 on the intermolecular asymmetric Mizoroki-Heck reaction, research on new and improved catalytic systems has become a field of growing interest. Over the last decade, efforts have been made to develop stable and easily synthesised ligands that induce high reactivity and selectivity (regio- and enantioselectivity) with a wide range of substrates. This review covers important developments in this field over the last decade by focusing on ligand design and applications. The article is organised according to the ligand class: [P,P], [P,N] and other ligand classes involved in the intermolecular asymmetric Mizoroki-Heck reaction.

This review gives an overview of our recent developments in the chemistry of 1,3- and 1,2-butadiene derivatives, with a special attention to their use in palladium catalyzed reactions. The reactions of α,β-unsaturated and propargylic acetals with various lithium and mixed lithium-potassium Schlosser reagents will be firstly reviewed. These processes have afforded (E)-1-alkoxy-1,3-dienes, and (E)-1,3-enynes, 1,3-diynes or allenes, respectively. When the reactions have been carried out in the presence of suitable electrophiles a linear route to functionalized derivatives has been set up. The above-mentioned compounds can be thus considered valuable synthetic tools for the construction of various and more complex structures and, in particular, they have been established to be useful reagents for the Suzuki-Miyaura cross-coupling reaction. As a matter of fact, alkoxy-functionalized butadienylboronic esters have been synthesized, cross-coupled with both N-protected and N-unprotected haloanilines (or halophenols), and finally transformed under mild conditions into quinolines and quinolinones (or chromenes and chromenones). The second part of the paper will deal with our recent interest in the Heck coupling of conjugate systems. In particular, the synthesis of γ-arylated α,β-unsaturated carbonyl compounds, by regioselective Heck process on 1-alkoxy-1,3-dienes in ionic liquids will be reviewed, in conjunction with the Heck coupling of 1,2-dien-1-ols to α-arylated α,β-unsaturated aldehydes. A survey of the recent literature on closely related topics will complete the contribution.

Organic functionalization of the semiconductor (100) surfaces of C, Si and Ge using traditional organic reactions has been attracting tremendous interest in the past decade, which has developed as a very hot and interesting topic at the border between material science and synthetic organic chemistry. In this review, we will give a brief summary of our recent research work in this regard. It is well demonstrated that, due to the structural similarity of the surface dimer of X (100) (X=C, Si and Ge) to alkenes, many well-known reactions associated with alkenes, such as carbenes addition reaction and Diels-Alder reaction, have been used to modify the (100) surface of C, Si and Ge successfully. In particular, a joint combination of theory and experiment empowers us to gain quick insight into the microscopic mechanism of chemistry of functionalization of the (100) surface of C, Si and Ge by synthetic organic reactions. All of these strongly advance the mantra of chemistry, i.e. similar structure dictates analogous function. In other words, fullerenes, carbon nanotubes and the (100) surface of X (100) all have an analogous bonding motif similar to alkenes, hence suggesting that similar chemistry is able to exist among them.

In this study, the title compound, N,N'-bis[(2,4-dimethoxyphenyl)methylidene]butane-1,4-diamine (L), was prepared and characterized by analytical and spectroscopic methods. The analytical data of the Schiff base ligand (L) confirms the proposed structure. The conductance value indicates that the ligand is non-electrolyte. The electrochemical properties of the ligand (L) are dependent on irreversible and quasi-reversible redox waves in the anodic and cathodic regions, due to oxidation and reduction. The single crystal of the ligand (L) was obtained from MeOH solution. Space group and crystal system of the ligand are P21/C and monoclinic, respectively. Unit cell dimensions of the ligand are a=4.0647(2) Å, b=17.4186 (10) Å, c= 13.8982(8) Å and β= 94.325 (1) .

This review focuses on a literature survey of the hydroarylation of alkynes via aryl C-H bond cleavage to prepare aryl-alkenes in the past thirty years. These efficient methods catalyzed by various metal complexes or protic acids are discussed respectively. Several reaction paths involved in these hydroarylations of alkynes are emphasized, which are aryl C-H activation by transition metals, formation of metal vinylidenes and Friedel-Crafts type process. In addition, some applications of these methods in organic synthesis are also introduced.

Chitosan is a natural polymer composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and Nacetyl- D-glucosamine (acetylated unit). It has been described as a non-toxic, biodegradable and biocompatible polymer with very interesting biological properties, such as permeation-enhancing and mucoadhesive properties, anticoagulant and antimicrobial activity and so on. Chitosan has been used in several areas such as biomedical, pharmaceutical and biotechnological fields as well as in the food industry. Recently, there has been a growing interest in the modification of chitosan to improve its solubility in physiological conditions, to introduce new applications or to improve chitosan biological properties. Research and development on a variety of amphiphilic copolymers containing hydrophobic and hydrophilic segments, have been very active due to their spontaneous self-assembly behaviour in aqueous media These smart transitions often lead to diverse functional compartment structures like micelles, vesicles and gels, which represent promising applications in the field of biotechnology and pharmaceutics. The aim of the present paper is to review the latest advances in the synthesis of chitosan amphiphilic derivatives with a special emphasis in their applications.