From ketones, aldehydes or alkyl halides to terminal 1,1-difluoroolefins using BrF3

Terminal difluoromethylenes were prepared by two different routes: (a) by treating ketones and aldehydes with bis(methylthio)methane, producing 2-alkyl-1,1-bis(methylthio)alkene (2) (b) reacting alkyl halides with tris(methylthio)methane forming 1-alkyl-1,1,1-tris(methylthio)alkane derivatives (7). The reaction of either 2 or 7 with BrF₃, followed by oxidation with HOF·CH₃CN gave the difluorosulfonyl derivatives 4. Consecutive treatment with Zn led to the target difluoroolefins (5) in overall yields of 60-75%.     

Complex of cesium and rubidium fluorides with bromine trifluoride

Vibrational spectra are reported for the new complexes CsF·3BrF₃, RbF·3BrF₃, and RbF·2BrF₃ and the previously known complex CsF·2BrF₃. The spectra suggest that these compounds are salts having general formulas M⁺Br₃F^?₁₀ and M⁺Br₂F^?₇.     

Stille cross-couplings of unactivated secondary alkyl halides using monoorganotin reagents

The first catalyst that achieves Stille cross-couplings of secondary (as well as primary) alkyl halides has been developed. The method employs easily handled and inexpensive catalyst components (NiCl2 and 2,2'-bipyridine) and, through the use of monoorganotin reagents, avoids the formation of toxic and difficult-to-remove triorganotin side products.     

The Barbier-Grignard-type carbonyl alkylation using unactivated alkyl halides in water

The aqueous Barbier-Grignard-type alkylation of aldehydes with unactivated alkyl iodides and bromides was developed. By using a combination of zinc and cuprous iodide, catalyzed by indium(I) chloride, we successfully added tertiary, secondary, and primary alkyl halides to various aromatic aldehydes in 0.07 M aqueous Na2C2O4. A mechanistic rationale for the success of the reaction has been proposed.     

The bromine catalysed oxidation of arsenic trifluoride by antimony pentafluoride

Antimony pentafluoride dissolves in excess arsenic trifluoride presumably with the formation of AsF₃·SbF₅ [1,2] and possibly (AsF₃)_nSbF₅ n = 2, [3], 3, [4], in equilibrium with one another and the solvent. However, O. Ruff [5] found in 1906 that in the presence of bromine, antimony pentafluoride oxidises arsenic trifluoride to arsenic pentafluoride with formation of a solid he suggested was SbBrF₄. In the course of our work we investigated this reaction and found that trace quantities of bromine (<0.1 mole per cent) catalyse the formation of arsenic pentafluoride and SbF₃·SbF₅ [6], according to equation (1).AsF₃ + 2SbF₅ = AsF₅ + SbF₃·SbF₅ (1)Reaction (2) is endothermic to the extent of ca. 33 Kcals mole^?1 [7–9], but reaction (1) occurs spontaneously in presence of bromine, being more favourable than reaction (2) by the heat of reaction (3).AsF₃ + SbF₅ = AsF₅ + SbF₃ (2)SbF₃ + SbF₅ = SbF₃·SbF₅ (3)     

Titanocene-catalyzed carbosilylation of alkenes and dienes using alkyl halides and chlorosilanes

A new method for regioselective carbosilylation of alkenes and dienes has been developed by the use of a titanocene catalyst. This reaction proceeds efficiently at 0 degrees C in THF in the presence of Grignard reagents by the combined use of alkyl halides (R'-X, X = Br or Cl) and chlorotrialkylsilanes (R3'Si-Cl) as the alkylating and silylating reagents, respectively. Terminal alkenes having aryl or silyl substituents (YRC=CH2, Y = Ar or Me3Si, R = H or Me) afford addition products YRC-(SiR'3)-CH2R' in good yields, whereas 1-octene and internal alkenes were sluggish. When 2,3-disubstituted 1,3-butadienes were used instead of alkenes, alkyl and silyl units are introduced at the 1- and 4-positions giving rise to allylsilanes in high yields under similar conditions. The present reaction involves (i) addition of alkyl radicals toward alkenes or dienes, and (ii) electrophilic trapping of benzyl- or allylmagnesium halides with chlorosilanes. The titanocene catalyst plays important roles in generation of these active species, i.e., alkyl radicals and benzyl- or allylmagnesium halides.     

Palladium-catalyzed silylations of hydrosilanes with aryl halides using bulky alkyl phosphine

[Reaction: see text]. A palladium-catalyzed direct trialkylsilyl transfer to aryl halides has been developed. In the presence of Pd(t-Bu3P)2 and K3PO4, electron-rich para- or meta-substitute aryl iodides were coupled efficiently with triethylsilane, triphenylsilane, and dimethylphenylsilane to afford the corresponding silylated products in moderate to good yields.     

Pd-catalyzed cross-coupling reactions of alkyl halides

Cross-coupling reactions have become indispensable tools for creating carbon-carbon (or heteroatom) bonds in organic synthesis. Like in other important transition metal catalyzed reactions, such as metathesis, addition, and polymerization, unsaturated compounds are usually employed as substrates for cross-coupling reactions. However during the past decade, a great deal of effort has been devoted to the use of alkyl halides as saturated compounds in cross-coupling reactions, which has resulted in significant progress in this undeveloped area by introducing new effective ligands. Many useful catalytic systems are now available for synthetic transformations based on C(sp(3))-C(sp(3)), C(sp(3))-C(sp(2)) and C(sp(3))-C(sp) bond formation as complementary methods to conventional C(sp(2))-C(sp(2)), C(sp(2))-C(sp) and C(sp)-C(sp) coupling. This tutorial review summarizes recent advances in cross-coupling reactions of alkyl halides and pseudohalides catalyzed by a palladium complex.     

Reaction of N-vinylimidazoles with alkyl halides

Quaternary salts of N-vinylimidazole and N-vinylbenzimidazole were synthesized. The structures of the products of quaternization of the N-vinylimidazoles were proved by IR and UV spectra. The distribution of the -electron density in the N-vinylimidazole molecules was obtained by quantum-chemical calculation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 958–960, July, 1971.     

A novel and efficient synthesis of alkyl thiocyanates from alkyl halides in water using phase transfer catalysts

1,4-Bis(triphenylphosphonium)-2-butene dichloride(BTPBDC) and 1,4-bis(triphenyl phosphonium)-2-butene dithiocyanate (BTPBDT) were prepared and used as phase-transfer catalysts.Alkyl halides were converted efficiently to the corresponding alkyl thiocyanates under mild reaction conditions in water.No evidence for the formation of isothiocyanates as by-product of the reaction was observed.     

The interconversion of primary alkyl halides

Using tetra-alkylammonium halides dissolved in alkyl halides as reagents a variety of halogen exchange reactions can be carried out conveniently in high yield. In particular, it becomes practicable to use -CH₂Cl as a protected equivalent of -CH₂Br.     

A new method for converting alkyl halides to homologous aldehydes

Phenylthiotrimethylsilylmethyl lithium can be alkylated and the product hydrolysed to the aldehydes by oxidation and rearrangement.     

Extraction of impurities of rare-earth elements from uranium dioxide using bromine trifluoride for their preconcentration and analytical determination

The behavior of impurities of rare-earth elements in the fluorination of UO₂ with bromine trifluoride is studied by the radioactive tracer method using¹⁵²Eu radionuclide. It is demonstrated that uranium is completely removed as hexafluoride, whereas impurities of rare-earth elements quantitatively remain in the crucible because of the nonvolatility of their fluorides. Based on this fact, the concentrations of rare-earth elements in UO₂ is determined. Results of analysis are in agreement with the data that were obtained using the conventional technique for the extraction of rare-earth elements from UO₂     

Nickel-catalyzed reductive cross-coupling of unactivated alkyl halides

A Ni-catalyzed reductive approach to the cross-coupling of two unactivated alkyl halides has been successfully developed. The reaction works efficiently for primary and secondary halides, with at least one being bromide. The mild reaction conditions allow for excellent functional group tolerance and provide the C(sp(3))-C(sp(3)) coupling products in moderate to excellent yields.