[(S)-BINAP]PdBr2-catalyzed direct synthesis of 2,3-disubstituted indoles via a tandem reaction between arylamines and α-diketones

A direct PdBr₂(BINAP)-complex catalyzed method has been developed to produce 2,3-disubstituted indoles by the reaction of arylamines with α-diketones under reductive (H₂) conditions. The synthetic methodology involves a tandem reaction of three steps and all the organic intermediates were isolated and characterized, the reduction products in this sequence are chiral and present interesting enantiomeric excess. This report constitutes a new and different route to synthesize indoles and a plausible mechanism is also suggested.     

Carbon-Nanotube-Appended PAMAM Dendrimers Bearing Iron(II) α-Keto Acid Complexes: Catalytic Non-Heme Oxygenase Models

Poly(amidoamine) dendrimers grafted on carbon nanotubes have been appended with iron(II)-α-keto acid (benzoylformate) complex of polypyridyl ligand to design artificial non-heme oxygenase model. This nano-enzyme was applied for selective catalytic oxidation of organic molecules. Although the carbon nanotubes serve as a robust heterogeneous platform, the amine terminals of dendrimers provide catalysts binding sites and the amide bonds provide a necessary second coordination sphere similar to the enzymatic polypeptide chains. Such a hybrid design prevented the deactivation of the primary active sites leading to 8 times faster oxidative decarboxylation rates than those of its homogeneous analogue. An electrophilic iron(IV)-oxo intermediate has been intercepted, which catalyzes the selective oxidation of alcohols to aldehydes and incorporates single oxygen atoms into sulfides and olefins by using aerial oxygen with multiple turnover numbers. The catalyst was consecutively regenerated three times by mild chemical treatment and showed negligible loss of activity.     

CONVENIENT ONE POT PROCEDURE FOR SYNTHESIS OF FORMYLATED CALIX[n]ARENES

A convenient one pot procedure for obtaining formyl calix [n]arenes via condensation with 1,1-dichloromethylmethylether is described.     

The Separation of Alanine Enatiomer Derivatives by the Proton‐Inhibition Method

Better peak shapes and complete separation of amino‐3,5‐dinitro derivatives by (S)‐N‐(2‐naphthyl)alanine derived chiral stationary phase (CSP) is achieved by adding a trace amount of acetic acid in the mobile phase. This method provides an indication of its broad applicability on direct separation of a series of amino‐containing enantiomers on CSP. In addition, the reversed elution order was obtained on its enatiomeric CSP.     

quiral: a computer program for the synthesis of chiral molecules from sugars

The quiral computer program analyzes the 3D structure of a target organic molecule to find which sugar(s) can be used as a starting material for its synthesis. The program also proposes schemes for the preparation of rare or unavailable sugars whose chiral centers fit with those of the target molecule. Castanospermine, an anti-HIV natural compound is chosen as an example to illustrate what the quiral program achieves.     

Enantioselective allylation of aldehydes with allyltrichlorosilane promoted by new chiral dipyridylmethane N-oxides

New chiral dipyridine N-monoxides and N,N′-dioxides, which possess an isopropylidene backbone between two pyridine rings, have been prepared from naturally occurring monoterpenes. Their utility as organocatalysts has been demonstrated in the enantioselective addition of allyltrichlorosilane to aldehydes. Enantioselectivities up to 85% ee have been obtained.     

Enantioselective trifluoromethylation of aromatic aldehydes catalyzed by combinatorial catalysts

A new combinatorial catalyst system containing the disodium (R)-binaphtholate prepared in situ and a chiral quaternary ammonium salt was developed for enantioselective trifluoromethylation of aromatic aldehydes in up to 71% ee. A possible intermediate for the binaphtholate activation of the TMSCF₃ and a catalytic cycle were proposed based on the experiments.     

Synthesis of optically active oligomers consisting of chiral phosphorus atoms: capture of an intermediate between a polymer and a small molecule

We describe here the synthesis and properties of novel optically active oligophosphines. The effect of the number of chiral phosphorus atoms on thermal properties and conformations is documented. In this study, we captured an intermediate between a polymer and a small molecule. To the best of our knowledge, it is primarily observed that a small molecule transforms into a polymer via an amorphous small molecule during the process of the elongation of the oligomer main chain.