Search

A new class of chiral phosphines belonging to the P-aryl-2-phosphabicyclo octane family (PBO) is prepared by enantioselective synthesis starting from lactate esters and 2,2-dimethylcyclopentanone enolate. A substantial effort was invested to probe the relationship between catalyst purity and enantioselectivity.

A method is developed for auxiliary-directed, palladium-catalyzed [beta]-arylation and alkylation of [sp.sup.3] and [sp.sup.2] C-H bonds in carboxylic acid derivatives. 8-Aminoquinoline auxiliary has produced the best results for alkylation of [sp.sup.3] and [sp.sup.2] C-H bonds, where functional group tolerance is observed and amino- and hydroxyl-acid derivatives are functionalized.

Microfluidics is used for implementing genetic algorithms (GA) for discovering new homogeneous catalysts by using the oxidation of methane by molecular oxygen as a model system. The Pt/Fe system has shown the compatibility of iron with the entire catalytic cycle and the approach of GA-guided evolution has the potential to accelerate the discovery in catalysis and other areas

A general method is developed for copper-catalyzed deprotonative dimerization of arenes by using oxygen as the terminal oxidant. The electron-rich and electron-poor heterocycles as well as electron-poor arenes are reactive and the method is tolerant to functionalities like nitro, cyano, dialkylamino and ester groups.

A general method is developed for in situ trapping of arylmetal intermediates by halogen, sulfur, ketone and aldehyde electrophiles, which has produced the functionalization of the most acidic position in arene. [K.sub.3]P[O.sub.4] base is used for functionalizing pentafluorobenzene, benzothiazole and benzoxazole.

A general method is developed for copper-catalyzed arylation of [sp.sup.2] C-H bonds with p[K.sub.a]'s below 35. Electron-poor arenes possessing at least two electron-withdrawing groups on a benzene ring is arylated and two arylcopper-phenanthroline complex intermediates are prepared independently.

The development a palladium-catalyzed benzamide sequence ortho-arylation/rection with [(C[F.sub.3]CO).sub.2]O for convenient one-pot synthesis of ortho-arylated benzonitriles and fluorenone derivatives is reported. The N-propyl benzamides is converted to fluorenones while N-cyclohexyl benzamides yield benzonitrile derivatives.

The article explains the development and efficiency of a new approach for direct arylation of heterocycle C-H bonds by aryl halides, using copper as a catalyst. The technique can be widely used for organic synthesis due to its readily available starting materials.

A study conducted demonstrates that anilides possessing a number of different acyl groups could be arylated by aryl iodides by using palladium catalysis. The arylation products could be converted to phenanthridines by the reaction with trifluoroacetic anhydride.

Two new palladium-catalyzed methods are developed for the direct ortho-arylation of free benzoic acids. Inter- and intramolecular isotope effects for the benzoic acid arylation by aryl chlorides are determined and are found to be the same with a magnitude of 4.4 pointing toward heterolytic C-H cleavage as the turnover-limiting step.

A strategy in which C-H activation reactions promoted by Pd(II) are combined with beta-heteroatom elimination to create a catalytic cycle and achieve the arylation of haloolefins is described. The catalytic cycle can be subdivided into four parts, which includes C-H activation.

A general method is described for the copper-catalyzed arylation and alkenylation of polyfluorobenzene C-H bonds. The results are obtained by using a combination of copper iodide catalyst, phenanthroline ligand, aryl bromide or aryl iodide coupling partner, and DMF or DMF/xylene mixed solvent.

A new arylation process based on C-H is developed and it allows for the beta-arylation of carboxylic acid derivatives and gamma-arylation of amine derivatives. Efforts are underway to extend this methodology to arylation of esters and alkenylation of amides and esters.

Studies on chiral phosphine catalysis for enantioselective acylation have revealed exceptional catalysts based on the 2-phosphabicyclo(3.3.0)octane skeleton. The first member of this catalyst family was observed to activate m-chlorobenzoic anhydride for aroyl transfer in the kinetic resolution of phenyl tert-butyl carbinol. It is interesting to note that the reaction was more than 100 times faster than with the original catalyst. Modifications of catalyst structure that might enhance phosphorus diastereoselectivity in the cyclization were examined.

The dual activation method using magnesium bromide (MgBr2) and a tertiary amine activated the hindered pivalic anhydride and converted it into a pivalate ester in 99% yield after 22 hrs. at room temperature. The amine and MgBr2 were mixed with linalool prior to reaction with the anhydride to minimize decomposition of the enolizable anhydride. Phthalic anhydrides and 1-methylcyclohexanol gave the highest yield although the reaction was slower than the corresponding benzoylations.