A Novel Bimetallic Tetrahedron Cobalt Complex Promoting the Addition of Diethylzinc to Benzaldehyde

Asymmetric catalytic addition of dialkyzinc to aldehyde using chiral ligands has become one of the most active areas in asymmetric synthesis. In recent years, various chiral ligands have exhibited good results in promoting this asymmetric addition1, such asβ- amino alcohol and chiral amine which possess chiral carbon centers, chiral ((6-arene) chromium complexes2, derivatives of Ferrocene3, which possess planar chirality, and BINOL and NOBIN4. Further development of novel catalysts is sti…     

First Enantioselective Synthesis of (2R,3R)-and(2S,3S)-2-(4-hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxan-6-carbaldehyde

Numerous lignans containing 1,4-benzodioxane nucleus represent a class of natural products with cytotoxic and hepatoprotective activities1,2. Recently we have reported the racemic total synthesis of sinaiticin, a flavonolignan of the 1,4-benzodioxane type which was isolated from sinaiticum leaves found in sinai region of Egypt, using 2-(4-hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxan-6-carbaldehyde as the key interme-diate3,4. This species exhibits significant inhibitory activity against the …     

Active Oxygen Radical Scavenging Ability of Water-Soluble β-Alanine C_(60) Adducts

The bioactivity study of C60 and its relative derivatives is of considerable importance. Functional fullerenes have peculiar biological activities, such as enzymatic inhibition, anti-HIV activity, neuroprotection, antibacterial activity, DNA cleavage, and photodynamic therapy et al.1. Neuroprotective properties are based on the facts that functional fullerenes have antioxidant properties and high reactivity toward free radical2. Active oxygen radical in biological system mainly include…     

A New Monodisperse Reactive Resin with Active Groups on the Particle Surface

The cross-linked polymer beads with reactive groups as active supports have been widely used in many fields such as chromatographic separation, solid phase synthesis, catalytic reaction, ion exchange and adsorption etc. In resent years, the synthesis and application of monodisperse polymer beads with different structures have been rapidly developed1~4. It is obvious that this type of monosized resin as matrix of active supports will be even more advantageous in some applications. This paper pr…     

The Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by 2-Methylquinoline Derived Chiral Ligands

One of the most important and fundamental synthetic procedures for the establishment of a carbon-carbon bond stereoselectively is the enantioselective addition of organometallic reagents to aldehydes affording chiral secondary alcohols1. In this process, a frequently used method is to perform the reaction in the presence of a chiral ligand such as amino alcohol2. Here, we first report that two new chiral ligands3, which were readily available by the reaction of chiral ketone with lithiated 2-m…     

Synthesis of Pyridazinonethiadiazoles as Possible Antifungal Agents

Pyridazine derivatives represent one of the most active classes of compounds possessing a wide spectrum of biological activity. They are widely used in pharmaceuticals and agrochemicals1. On the other hands, 1,3,4-thiadiazole derivatives exhibit a broad spectrum of biological activity2-5. In view of these facts and in continuation of our interest in the chemistry of pyridazines, it was attempted to synthesize novel tri-heterocyclic compounds containing both pyridazinone and 1,3,4-thiadiazole m…     

Theoretical Studies on the Conformation of mono-6-O-p-nitrobenzoyl-β-cyclodextrin in Aqueous Solution

It is well known that a substituted cyclodextrin (CD) can often form a self-included complex, in which the substituent group is incarcerated into the CD cavity1. The phenomenon is interesting, as the self-inclusion is a nice model of protein folding2 and it has also been successfully used in the construction of various molecular devices3. Studies have showed that van der Waals force, hydrophobic effect, and electrostatic interaction are the major driving forces leading to the self-inclusion4…     

Microwave-assisted Polymerization of D,L-Lactide with Stannous Octanoate as Catalyst

Poly (lactic acid) (PLA) is an important member of the polyesters which are used as biomedical materials in bioresorbable suture, implantates and drug controlled release systems1. PLA is prepared by two routs2: ring-opening polymerization of dimeric cyclic lactide or direct polycondensation of lactic acid. The ring-opening polymerization has attracted much more scientific and industrial interests than the later one, but both methods need long time for the polymerization reactions to be compl…     

Synthesis and Photochemistry of Diphenylchlorin and Diphenylbacteriochlorin

5, 15-Diphenylporphyrin (DPP), a novel porphyrin model compound, was always inaccessible in quantities suitable for study1 because the difficulty of synthesis. So that the characteristic of this molecule had not been explored until a novel method developed for the preparation of DPP recently2. Therefore it will be possible for the synthesis of DPP-based photosensitizers, and investigation of their photodynamic properties. Here we reported the synthesis of novel photosensitizers 5, 15-diphe…     

The CH_3OH+Cl Hydrogen Abstraction Reactions: An ab initio Study

The hydrogen abstraction from methanol by atomic chlorine can proceed via two possible channels: CH3OH + Cl → CH2OH + HCl (i) → CH3O + HCl (ii)In 2000, Ahmed et al1. reported their investigation for the H abstraction dynamics of the CH3OH+Cl reaction by crossed molecular beams in conjunction with velocity map imaging. Hydroxymethyl (CH2OH) was detected in their experiments. In 1998, Jodkowski et al2. reported their theoretical study on the CH3OH+Cl reactions. They located inte…