BF(3)-monohydrate is found to be an efficient and strong acid catalyst as well as an effective protosolvating medium suitable for the hydroxyalkylation of arenes with aromatic aldehydes. This reaction has been extended to aromatic dialdehydes, such as terephthalic dicarboxaldehyde and isoterephthalic dicarboxaldehyde, for the efficient synthesis of diarylmethylbenzaldehydes, which are useful synthons for various organic transformations. Further, successful one step convergent synthesis of various synthetically useful anthracene derivatives from phthalaldehyde was also achieved. BF(3)-H(2)O is less expensive and acts as an efficient substitute for nonoxidizing strong protic acids/superacids.

[reaction: see text] A mixture of nitrate salt and chlorotrimethylsilane is found to be an efficient regioselective nitrating agent for the ipso-nitration of arylboronic acids to produce the corresponding nitroarenes in moderate to excellent yields. High selectivity, simplicity, and convenience are the key features of the reaction.

Organofluorine compounds are becoming increasingly important in different fields, such as material science, agro chemistry, and the pharmaceutical industry. Nucleophilic trifluoromethylation is one of the widely used methods to incorporate a trifluoromethyl moiety into organic molecules. We have carried out extensive studies to develop varieties of easily accessible nucleophilic catalysts to promote such reactions. TMS-protected trifluoromethylated alcohols were prepared from both aldehydes and ketones in excellent yields using catalytic amount of amine N-oxide. Carbonate and phosphate salts also showed efficient catalytic activity toward this reaction. These reactions were highly solvent dependent, and DMF was found to be the most suitable one among the various solvents studied. All these reactions proceeded under very mild conditions, giving clean products and avoiding the use of any fluoride initiators or expensive catalysts, and extremely water-free conditions. The mechanism for the reaction is discussed in detail. DFT calculations were performed on the possible reaction intermediates using the Gaussian 03 program at B3LYP/6-311+G* level to support the proposed mechanism.

The synthesis of ␣-aminonitriles and their fluorinated analogs has been carried out in high yield and purity by the Strecker reaction from the corresponding ketones and amines with trimethylsilyl cyanide using gallium triflate in dichloromethane. Monofluoro-, difluro-, or trifluoromethyl groups can be incorporated into the ␣-aminonitrile product by varying the nature of the fluorinated ketones. Study with various fluorinated and nonfluorinated ketones reveals that the choice of proper catalyst and the solvent system (suitable metal triflates as a catalyst and dichloromethane as a solvent) plays the key role in the direct Strecker reactions of ketones.three-component reaction ͉ ␣-aminonitriles

A mixture of nitrate salt and chlorotrimethylsilane is found to be a mild and efficient reagent for the direct oxidative conversion of thiols (1) and disulfides (2) to the corresponding sulfonyl chlorides (3) in excellent yields through oxidative chlorination. Sulfides and sulfoxides were also found to undergo oxidation to sulfones under similar reaction conditions. In most cases these reactions are highly selective, simple, and clean, affording products in high yield and purity.

Cyanosilylation of aldehydes and aliphatic ketones can be carried out in dimethylformamide even without the use of any catalyst. In the presence of nucleophilic catalysts such as carbonate and phosphate salts, the reaction rate is significantly enhanced.nature of solvent C yanohydrins (1) serve as key intermediates in the synthesis of biologically important compounds such as ␤-amino alcohols, ␣-hydroxy acids, ␣-hydroxy ketones, and ␣-amino acids. The possibilities to obtain a wide range of 1,2-bifunctional compounds by using both the hydroxyl and nitrile groups enhance their use as versatile building blocks in synthetic organic chemistry. Hydrogen cyanide (HCN) is the most commonly industrially used reagent for cyano transfer to carbonyl compounds (2). However, due to its toxicity and difficulty in handling, new methods have been developed to substitute HCN with other potentially less harmful and yet easily manageable reagents.Trimethylsilyl cyanide (TMSCN) is widely used as a cyanide source with various catalysts. The use of TMSCN dates back to the early 1970s. In 1973, Evans and Truesdale (3, 4) were among the first to report the use of anionic catalysts with TMSCN. Since then, a multitude of different catalysts has been reported in the literature for both the racemic and asymmetric addition of the cyanide to carbonyls. Majority of these catalysts are based on metallic Lewis acidic systems (5-22) containing a variety of ligands that enable enantioselective transfer of CN Ϫ to carbonyls. Izumi et al. (23) have reported cyanosilylation of carbonyl compounds with TMSCN using inorganic solid acids (varioius ion exchanged montmorillonites) and bases (basic solids such as CaF 2 , CaO, MgO, etc.) as catalysts. Kagan and coworkers (24,25) have reported the use of mono-and dilithium salts of binol. Recently, Ishiahara and coworkers (26) have modified this system by introducing a water/alcohol mixture as a coactivator. There has been also an increased interest in nonmetallic catalytic systems. Deng (27, 28), Plummet (29, 30), Corey (31), Jacobsen (32), and Feng (33) have reported systems based on chincona alkaloids, phosphonium salts, oxazaborolidinium ions, modified thiourea, and chiral amino acids, respectively, as good catalysts for cyano transfer from TMSCN. With the exception of the phosphonium salts, the rest are chiral catalysts and afford the products in high enantioselectivities. Recently, Denmark and Chung (34) conducted a brief survey of effective solvents, catalysts, and kinetics of Lewis base catalyzed addition of TMSCN to aldehydes. We now report our study of these reactions in dimethylformamide (DMF) using nucleophilic catalysts such as carbonates and phosphates. The convenient and inexpensive reaction conditions do not require any air and moisture free environment. We found that the CN to carbonyl transfer in N,N-dimethylformamide can be carried out even in the absence of a catalyst. With the addition of K 2 CO 3 or organic phosphate as catalyst, the rate of the reaction has been significantly enhanced...

Solid hydrogen peroxide complexes based on poly(N-vinylpyrrolidone) and poly(4-vinylpyridine) were prepared and used as solid hydroxylating reagents. These solid hydrogen peroxide equivalents are found to be much safer, convenient and efficient reagent systems for the ipso-hydroxylation of arylboronic acids to the corresponding phenols in high yields at a faster rate. The versatility of the reagents has been further expanded for the one-pot synthesis of halophenols. Density functional theory calculations were carried out on hydrogen peroxide complexes of N-ethylpyrrolidone and 4-ethylpyridine as models to get a better understanding of structure and behavior of hydrogen peroxide complexes of the polymers poly(N-vinylpyrrolidone) and poly(4-vinylpyridine) compared to aqueous hydrogen peroxide.

One-pot synthesis of fluorinated benzimidazolines, benzothiazolines, benzoxazolines, and dihydrobenzoxazinones was easily achieved under mild conditions in high yields and purity through gallium(III) triflate mediated condensation-cyclization. Introduction of fluorine atoms favors the formation of the five-membered heterocycles over seven-membered heterocycles. [reaction: see text].