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.

Abstractα,β-Difluoromethylene deoxynucleoside 5'-triphosphates (dNTPs, N = A or C) are advantageously obtained via phosphorylation of corresponding dNDP analogues using catalytic ATP, PEP, nucleoside diphosphate kinase (NDPK) and pyruvate kinase (PK). DNA pol β K d values for the α,β-CF 2 and unmodified dNTPs, α,β-NH dUTP, and the a,β-CH 2 analogues of dATP and dGTP are discussed in relation to the conformations of α,β-CF 2 dTTP v. α,β-NH dUTP bound into the enzyme active site.In an ongoing multidisciplinary study of structure and function of DNA polymerase β, a eukaryotic enzyme primarily involved in filling short DNA gaps 1 , we required a series of α,β-methylene-substituted analogues of deoxynucleoside 5'-triphosphates (dNTPs). When the *Email Address: mckenna@usc.edu. Supporting Information Available General methods used; detailed synthetic procedures and characterization data for 1 -9; analytical and preparative HPLC methods; HPLC studies of conversions of 1 to 2, 2 to 3, 7 to 4, 4 to 5, 5 to 6; 1 H NMR spectra of 1-7 and 9; 31 P and 19 F NMR spectra of 2, 3, 5, 6, 9; 13 C NMR spectrum of 9; analytical HPLC traces for 3, 6 and 9; HRMS spectra for 3 and 6, and LRMS spectrum for 9; DNA synthesis gel analysis of 9 before and after HPLC purification; protocol and inhibition plot for inhibition of pol β dCTP incorporation by 6; crystallographic methods and statistics for the ternary pol β complex with 9; and supplementary literature references are available online at http://pubs.acs.org. P α -O-P β bridging oxygen in a natural mononucleotide substrate is replaced by an imido (NH) 2-4 or methylene (CXY) 4,5 group, the P-N or P-C bond should resist cleavage in the nucleotidyl transfer reaction catalyzed by the enzyme. As a result, these analogues will remain intact in stable ternary DNA complexes with the polymerase and therefore should be useful to probe pre-chemistry enzyme-complex function and structure, as recently shown with in an X-ray crystallographic study of α,β-NH dUTP with DNA pol β. 6 Information about such complexes provides a reference point for theoretical analysis of the chemical mechanism 7 for the complete transfer of a monophosphate nucleoside donor to the sugar acceptor in the active site. As probes for the mechanism of polymerase catalysis and its relationship to polymerase fidelity, α,β-methylene dNTP analogues permit exploration of stereoelectronic effects on active site interactions, by making appropriate substitutions X,Y on the adjacent P α CXY bridging carbon. The largest obtainable electron-withdrawing effect with minimal steric perturbation can be achieved using X,Y = F, resulting in analogues in which the bisphosphonate group is expected to be less basic than the pyrophosphate moiety in the natural dNTPs. 8,9 In this article, we describe the first synthesis of α,β-CF 2 dCTP 6, using a modified chemicalenzymological approach that also can be applied to synthesis of α,β-CF 2 dATP 3, affording these compounds in sufficient purity to virtually eliminate detectable contaminating substrate ...

The potential of using organogermatranes in palladium-catalyzed cross-coupling with aryl iodides has been investigated. We have found that organogermatranes are less reactive in this analogue of Stille coupling than trialkylorganostannanes; nevertheless activation by fluoride promotes the reaction. The hypervalent germanium species produced from the germatranes provide a more efficient and more easily handled reagent than trialkoxygermanium analogues.

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...

The structures of n-B18H22 and of n-B18H22 x C6H6 were determined by single-crystal X-ray analysis at -60 degrees C. The geometry of the boron cluster itself does not seem to be appreciably affected by solvation. There does, however, appear to be an unusual interaction of a polyborane bridging hydrogen atom with the benzene pi system, giving rise to an extended stacked structure. The 1H{11B} spectrum of n-B18H22 in [D6]benzene differs from that in [D12]cyclohexane most noticeably in the bridging proton region. Upon moving from the aliphatic to the aromatic solvent, the greatest increase in shielding was for the signal corresponding to the bridge hydrogen atom that interacts with the pi system of benzene; the signal was shifted upfield by 0.49 ppm. Density functional theory calculations were performed on 1:1 and 2:1 complexes of the n-B18H22 unit with benzene.

The 1,2-, 1,7-, and 1,12-isomers of (Me2S)2B12H10 (O, M, and P) react with potassium phthalimide in DMF or EtSNa in CH3CN/EtOH upon reflux producing the corresponding isomers of [(MeS)(Me2S)B12H10]- (O1-, M1-, P1-). If excess of either nucleophile is used, [Me2SB12H11]- (1) and O, M, P can be converted into dianions [MeSB12H11]2- (2) and [(MeS)2B12H10]2- (O2-, M2-, P2-). The use of EtSNa is recommended since it facilitates the isolation of products compared to the potassium phthalimide method. When 1 or O, M, P are treated with an excess of an alkali metal (Na, K) in liquid ammonia at -40 degrees C, sulfide 2 or bissulfide dianions O2-, M2-, P2- are obtained cleanly and almost instantly. While both the nucleophilic substitution and alkali metal reduction methods are useful for the synthesis of dianions 2, O2-, M2-, and P2-, only the former method is suitable for the synthesis of the sulfide-sulfonium anions O1-, M1-, P1-. The analysis of the 11B NMR spectra of 1, O, M, P and anions derived from them demonstrated that the spectra of the disubstituted species can be predicted qualitatively, keeping in mind the simple substituent effects obtained from the spectra of monosubstituted anions 1 and 2. Some evidence is found for small partial double bond character of the B-SMe bonds in anions. [MePPh3]+ salts of [MeSB12H11]2- (2) and [1-(MeS)-7-(Me2S)B12H10]- (M1-) are structurally characterized by single-crystal X-ray diffraction analysis. Crystal data: [MePPh3]2[MeSB12H11], P2(1) (No. 4), a = 9.243(1) A, b = 18.272(1) A, c = 12.548(1) A, beta = 103.17(1) degrees, Z = 2; [MePPh3][1-(MeS)-7-(Me2S)B12H10], P1 (No. 2), a = 9.278(2) A, b = 12.003(5) A, c = 14.819(7) A, alpha = 112.18(4) degrees, beta = 105.61(3) degrees, gamma = 92.91(3) degrees, Z = 2.

The pyrolysis of BH3·SMe2 at 130 °C and 1000 psi yields isomers of (Me2S)2B12H10. The previously unreported 1,2 isomer has been isolated and characterized by single-crystal X-ray analysis and multinuclear NMR spectroscopy. Its physical and spectral characteristics are compared to those of the earlier reported 1,7 and 1,12 isomers of (Me2S)2B12H10.

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