Selective palladium-catalyzed C-F activation/carbon-carbon bond formation of polyfluoroaryl oxazolines

A selective palladium-catalyzed Suzuki-Miyaura coupling reaction of polyfluorophenyl oxazolines through ortho C-F activation is described. It was found that reactions with DPPF as the ligand occurred much faster than those with other ligands. A variety of arylboronic acids including challenging functionalized arylboronic acids such as enolizable ketones, aldehyde, cyano, ester, and trifluoromethyl groups were tolerated with the reaction conditions.     

Modular chiral selenium-containing oxazolines: synthesis and application in the palladium-catalyzed asymmetric allylic alkylation

A new series of modular chiral selenium-containing oxazolines has been synthesized from inexpensive and commercially available l-serine and l-aspartic acid. These new compounds were evaluated as chiral ligands in the palladium-catalyzed asymmetric allylic alkylation reaction, furnishing the product in high enantiomeric excess, using Cs₂CO₃/CH₂Cl₂ as the base/solvent system.     

One pot direct synthesis of oxazolines, benzoxazoles, and oxadiazoles from carboxylic acids using the Deoxo-Fluor reagent

A one-pot, high yield direct synthesis of various 2-substituted oxazolines, benzoxazoles, and 2-oxadiazoles from carboxylic acids using Deoxo-Fluor reagent is described.     

A novel palladium-catalyzed dicarbonylation process leading to coumarins

A novel approach to coumarin derivatives has been developed starting from readily available 2-(1-hydroxyprop-2-ynyl)phenols, based on an unprecedented palladium-catalyzed dicarbonylation process. Reactions were carried out in the presence of catalytic amounts of PdI2 in conjunction with an excess of KI in MeOH as the solvent at room temperature and under 90 atm of CO to give 3-[(methoxycarbonyl)methyl]coumarins in good to high isolated yields (62-87%).     

A palladium-catalyzed three-component reaction for the preparation of quinazolin-4(3H)-imines

A novel and efficient route for the preparation of quinazolin-4(3H)-imines via a palladium-catalyzed three-component reaction of carbodiimide, isocyanide, and nucleophile is described. The palladium-catalyzed isocyanide insertion is believed to be the key step during the reaction process.     

Selectively substituted thiophenes and indoles by a tandem palladium-catalyzed multicomponent reaction

A variety of di- and trisubstituted thiophenes were synthesized by a one-pot palladium-catalyzed ortho-alkylation sequence terminated by either Heck or C-H coupling. Initial results toward the functionalization of indoles are also presented.     

A one-pot multicomponent Biginelli reaction for the preparation of novel pyrimidinthione derivatives as antimicrobial agents

A convenient synthesis of pyrimidinthiones was carried out in presence of thiourea and easily available catalyst sulfamic acid ( 2a-t) . One-pot Biginelli reaction is very important due to the use of simple and readily available chemicals, less reaction time, economically friendly, and furnishing good yield. Structures of the synthesized compounds are characterized by spectral techniques like IR, ¹H-NMR, ¹³C-NMR, and LC–MS. Synthesized compounds were studied for their antimicrobial activity against several strains of bacteria (E. coli, P. aeruginosa, and S. aureus, S. pyogenes) and fungi (C. albicans, A. niger, and A. clavatus) using serial dilution method.     

A palladium-catalyzed multicomponent synthesis of imidazolinium salts and imidazolines from imines, acid chlorides, and carbon monoxide

A palladium-catalyzed multicomponent synthesis of imidazolinium carboxylates and imidazolines is described. The palladium catalyst [Pd(CH(R(1))N(R(2))COR(3))Cl](2), or [Pd(allyl)Cl](2), with P(t-Bu)(2)(2-biphenyl) can mediate the simultaneous coupling of two imines, acid chloride, and carbon monoxide into substituted imidazolinium carboxylates within hours under mild conditions (45 °C, 4 atm of CO). The reaction proceeds in good yield with aryl-, heteroaryl-, and alkyl-substituted acid chlorides, as well as variously functionalized imines. Imidazolines are formed via the initial generation of Mu?nchnone intermediates, followed by their cycloaddition with an in situ generated protonated imine. The addition of an amine base can intercept catalysis at Münchnone formation, which allows the subsequent cycloaddition of a second imine. The latter provides a route for the assembly of complex, polysubstituted imidazolinium carboxylates with independent control of all five substituents. The subsequent removal of the nitrogen substituent(s) provides an overall synthesis of imidazolines.     

The preparation of 2-iodoamides from glucals and their further transformations into oxazolines

2-Deoxy-2-iodo-glycosylamides have been prepared from a variety of protected d-glucals by their reaction with N-iodosuccinimide and amides. Benzyl protected 2-iodoamides, when treated with sodium hydride and 15-crown-5, gave stable C1 N-linked 2-glycooxazolines as the major products. Silyl protected 2-iodoamides afforded the C1 O-linked 2-glycooxazolines; presumably by the rearrangement of unstable N-acylaziridine intermediates.     

Spectrophotometric flow-injection techniques for the multicomponent monitoring of process streams

An overview of simultaneous determinations in flow-injection analysis (FIA) is presented and the advantages of photodiode array detection are discussed. The application of multivariate calibration procedures to nonselective data is outlined and examples of its use in FIA are reviewed. The role of flow-injection techniques in process analysis and the potential of FIA-photodiode array-multivariate calibration systems for on-line multideterminations are also considered.     

Enantioselective chromatography as a powerful alternative for the preparation of drug enantiomers

The preparative separation of enantiomers by chromatography on chiral stationary phases (CSPs) has been recognized as being a useful alternative to the more conventional approaches such as enantioselective synthesis and enzymatically catalyzed transformations. The possible contribution of enantioselective chromatography with respect to the preparation of enantiomerically pure compounds is reviewed in the context of the competitive approaches and depending on the application scale, with a special emphasis on the recent progresses achieved in this particular field of separation.     

Electrochemical fluorination (Simons process) – A powerful tool for the preparation of new conducting salts, ionic liquids and strong Brønsted acids

Electrochemical fluorination (Simons process) provides a cheap commercial access to a series of tris(perfluoroalkyl)diflurophosphoranes. These substances are convenient starting material for the preparation of various fluoro-chemicals. The synthesis of new conducting salts and ionic liquids with perfluoroalkyl-fluorophosphate (FAP) and perfluoroalkyl-phosphinate anions is described. FAP ionic liquids exhibit excellent hydrolytic stability, low viscosity and high electrochemical and thermal stability. Organic and inorganic salts with FAP anions possess high electrochemical stability and conductivity that makes them attractive for application in several electrochemical devices (Li-ion batteries, super-capacitors, etc.). The possible application of H[(R_F)₃PF₃] (HFAP), (R_F)₂P(O)(OH) and (R_F)P(O)(OH)₂ as components of proton-conducting membranes is discussed.     

Intermolecular palladium-catalyzed coupling of 2-halopyridines and alcohols for the preparation of pyridine ether PPAR agonists

A series of pyridine ether PPAR agonists were synthesized through intermolecular palladium-catalyzed coupling of 2-halopyridines and alcohols. This method proved to be versatile, efficient, and amenable to parallel synthesis.     

Copper-catalyzed multicomponent cascade process for the synthesis of hexahydro-1H-isoindolones

Copper-catalyzed coupling of imines, dienylstannanes, and acryloyl chlorides followed by a Diels-Alder reaction afforded hexahydro-1H-isoindolones. Diversification of the core via Pd-catalyzed cross-coupling defines a new modular approach to isoindolone combinatorial libraries.     

Functionalized orthoesters as powerful building blocks for the efficient preparation of heteroaromatic bicycles

By combining substituted anilines with functionalized orthoesters, an efficient and connective methodology for the preparation of benzoxazole, benzothiazole, and benzimidazole derivatives has been established. The versatility of this approach enables the development of new libraries of heterocycles containing multifunctional sites.     

Efficient preparation of monohydrosilanes using palladium-catalyzed Si-C bond formation

The arylation of dihydrosilanes with aryl iodides or heteroaryl iodides in the presence of a palladium catalyst provides the corresponding monohydrosilanes in good to high yield. Moderate to good yields are obtained even in the presence of a variety of reactive functional groups, such as -NH2, -OH, or -CN, without their protection.     

An efficient method for the preparation of tertiary esters by palladium-catalyzed alkoxycarbonylation of aryl bromides

The palladium-catalyzed alkoxycarbonylation of aryl bromides is described for the efficient preparation of tertiary esters. The protocol proved compatible with a wide variety of functionalized (hetero)aromatic bromides, as well as several different sterically hindered tertiary alcohols, affording the alkoxycarbonylated products in high yields. Finally, the formation of aromatic trityl esters is discussed.     

Uncatalyzed and solvent-free multicomponent process for the synthesis of biphenyl-2-carbonitrile derivatives

An innovative route to prepare a number of variously substituted new biphenyl derivatives is presented here. The protocol avoids the use of a catalyst, an organic solvent, and dry conditions. [reaction: see text]