Alexander A. Kolomeitsev

Pentakis(trifluoromethyl)phenyl, a sterically crowded and electron-withdrawing group: synthesis and acidity of pentakis(trifluoromethyl)benzene, -toluene, -phenol, and -aniline.

A general route to functionalized pentakis(trifluoromethyl)phenyl (C6(CF3)5) derivatives, promising building blocks for designing novel stable carbenes, radical species, superacids, weakly coordinating anions and other practically and theoretically useful species, is presented. This pertrifluoromethylation route proceeds via conveniently pregenerated (trifluoromethyl)copper (CF3Cu) species in DMF, stabilized by addition of 1,3-dimethyl-2-imidazolidinone (DMI). These species react with hexaiodobenzene at ambient temperature to give the potassium pentakis(trifluoromethyl)phenoxide along with hexakis(trifluoromethyl)benzene and pentakis(trifluoromethyl)benzene in a combined yield of 80%. A possible reaction pathway explaining the formation of pentakis(trifluoromethyl)phenoxide is proposed. Pentakis(trifluoromethyl)phenol gives rise to easily functionalized pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)aniline. Pertrifluoromethylation of pentaiodochlorobenzene and pentaiodotoluene allows straightforward access to pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)toluene, respectively. XRD structures of several C6(CF3)5 derivatives were determined and compared with the calculated structures. Due to the steric crowding the aromatic rings in all C6(CF3)5 derivatives are significantly distorted. The gas-phase acidities (Delta Gacid) and pKa values in different solvents (acetonitrile (AN), DMSO, water) for the title compounds and a number of related compounds have been measured. The origin of the acidifying effect of the C6(CF3)5 group has been explored using the isodesmic reactions approach.

Nucleophilic trifluoromethylation of organic substrates using (trifluoromethyl)trimethylsilane in the presence of a fluoride anion II. A convenient route to aryltrifluoromethyl-sulfides, -sulfoxides and -sulfones☆

Abstract Aryltrifluoromethyl-sulfides, -sulfoxides and -sulfones can be prepared by trifluoromethylation of the corresponding arylsulfenyl, -sulfinyl and -sulfonyl halides using (trifluoromethyl)trimethylsilane in the presence of fluoride sources, such as TASF [tris(dimethylamino)sulfonium difluorotrimethylsilicate].

Simple preparation of difluorophosphoranes using anhydrous zinc and tetramethylammonium fluorides

Abstract Bromophosphonium bromides, R 3 PBr + Br − (R= n Bu, NMe 2 , NEt 2 ) are easily fluorinated using zinc difluoride in pyridine or tetramethylammonium fluoride in methylene chloride to give the corresponding difluorophosphoranes R 3 PF 2 in high yield. A simple procedure for preparing pure tetramethylammonium fluoride is described.

Generation of heteroarylium-N-difluoromethylides and heteroaryl-N-difluoromethyl anions and their reactions with electrophiles: heteroaryl- and heteroarylium-N-difluoromethyl trimethylsilanes and a new heteroaryl-N-trifluoromethane

Abstract Reductive debromination of N -bromodifluoromethyl-4-dimethylaminopyridinium bromide, 1-bromodifluoromethyl-imidazole, 1-methyl-3-bromodifluoromethyl-imidazolium bromide and 1-bromodifluoromethyl-2-methyl-benzimidazole using tetrakis(dimethylamino)ethylene (TDAE) or tris(diethylamido)phosphite leads to new fluorinated carbanionic species, namely heteroarylium- N -difluoromethylides and heteroaryl- N -difluoromethyl anions. In the presence of electrophiles such as benzaldehyde, chlorodiphenylphosphine and chlorotrimethylsilane, the corresponding heteroarylium- and heteroaryl- N -difluoromethylated derivatives, imidazole- N -difluoromethyl-phosphines and -silanes, 2-methyl-benzimidazole- N -difluoromethyltrimethyl-carbinols-phosphines and -silanes were obtained. Similar 4-dimethylaminopyridinium derivatives were synthesized.

Facile syntheses of tris(trifluoromethyl)phosphine and difluorotris (trifluoromethyl) phosphorane

Abstract Tris(trifluoromethyl) phosphine is easily available in high yield using the three component system D(NAt)2)3/NF3Ar/(DhI)3D in IIDA. Addition of chlorine and fluorination with zinc difluoride yield difluorotris (trifluoromethyl) phosphorane.

Advances in Trifluoromethylating Phosphorus Compounds

Abstract The System CF3I/Me3P is re-investigated and Me2PCF3, Me4P+γ, (CF3)2PMe3, Me3PI2, [Me3(CF3)P]+γ are found as products. Using CF3Br/P(NEt2)3 the phosphines R1 2PCF3 and R1P(CF3)2 (e.g. R1 = Me, iPr, NEt2) can be obtained which are precursors either for phosphoranes (e.g. 1,2λ5σ5-oxaphosphetanes) or phosphonium salts (e.g. [R1 2(Me)PCF3]+X− or [R1(Me)P(CF3)2X−]. The latter are deprotonated to furnish methylene phosphoranes R1 2(CH2=)PCF3 or R1(CH2=)P(CF3)2, reactive synthons. From CF3Br/P(NEt2)3/P(OPh)3 the phosphine P(CF3)3 is available, which turned out to be a potent electrophile. Amido phospites ROP(NEt2)2 and halides R2X (R2=CCl2CF3, X=Cl; R2=CF=CFCF3, X=F; R2=C6F5, X=Br, I; R2=C(CF3)3, X=Br; R2=SCF3, X=CF3) undergo an ARBUZOV reaction.

Facile new method for synthezising N-polyfluoroalkylated heterocycles – molecular structure of N-(bromodifluoromethyl)-4-dimethylaminopyridinium bromide

Carbon-bromine bond cleavage is observed when 4-dimethylaminopyridine is treated with CF2Br2 and BrCF2CF2Br to yield N-(bromodifluoromethyl) and N-(2-bromo-1,1,2,2-tetrafluoromethyl)pyridinium bromides, 1-Br and 2-Br, which are reductively debrominated using Bu3SnH and fluorinated by anhydrous Me4N+F–; the molecular structure of 1-Br is determined by single crystal X-ray crystallography to reveal a partial quinoidal character in the pyridine system and a hypervalent Br–⋯BrCF2 pairing.

Tris(dimethylamino)sulfonium 1,1,2,4,5-pentakis(trifluoromethyl)- 2,5-cyclohexadienide - a new stable fluorinated carbanion salt prepared by anionic trifluoromethylation of 1,2,4,5-tetrakis(trifluoromethyl)benzene

Abstract An interaction of the 1,2,4,5-tetrakis(trifluoromethyl)benzene with the pseudomettalorganic system CF 3 SiMe 3 /TASF results in addition of TAS + CF 3 − to the benzene ring and formation of TAS + (CF 3 ) 5 C 6 H 2 t- - a new stable tertiary fluorinated delocalized carbanion salt.

Molecular structures and reactivity of trifluoromethyltris(dialkylamino)phosphonium bromides

Abstract Hexa-alkylphosphorus triamides and trifluoromethyl bromide react to give trifluoromethyltris(dialkylamino)phosphonium bromides which were used for the trifluoromethylation of benzaldehyde and copper(I) iodide in the presence of fluoride anions with different counterions; tris(diethylamino)difluorophosphorane proved to be a masked fluoride anion donor. The structures of [CF3P(NMe2)3]+Br− and [CF3P(NEt2)3]+Br− have been determined by single-crystal X-ray investigations and shown to exhibit a distorted tetrahedral bond configuration with a rather long (F3)CP bond of 1.866(9) or 1.896(6) A, respectively.

Reaktionen an Trifluormethyl-Dimethylphosphin: Molekulstruktur Von [3,3,3-Trifluor-2-Hydroxy-2-(Trifluormethyl)]Propylmethyl-Trifluormethyl-Phosphinoxid

Abstract Trifluormethyldimethylphosphine (1) added methyl iodide to give the respective phosphonium iodide 2 which was easily fluorinated using tetramethylammonium fluoride or difluorotris(diethylamino)-phosphorane yielding fluorotrifluoromethyltrimethylphosphorane (3). Hexafluoroacetone and trifluorodimethylphosphine reacted in a 2:1 ratio furnishing 2-methyl-2-[1,1,1-trifluoro-2-(trifluoromethyl)]ethoxy-2-(trifluoromethyl)-4,4-bis(trifluormethyl)-1,2λ5[sgrave]5-oxaphosphetane (4) which underwent hydrolysis forming [3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)]propylmethyltrifluoromethylphosphine oxide (5). Upon treating compound 5 with SOCl2/pyridine again an oxaphosphetane, phosphorane 6 was obtained, which could be fluorinated to give the fluorophosphorane 7. The solid state molecular structure of the phosphine oxide 5 showed a distorted tetrahedral geometry at phosphorus and a rather long inter-molecular hydrogen bridge —O—H…O = P(O…O = 266.3 pm).