Fluoro-ketones VII. Synthesis of perfluoro mono- and di-ketones from perfluoro-grignard or lithium reagents and diethyl carbonate and diethyl oxalate

The reaction between perfluoroalkyl-Grignard or lithium compounds and diethyl carbonate has been investigated. Under appropriate conditions, symmetric or asymmetric ketones can be prepared. The reactions of the perfluoro- Grignard or lithium compounds with diethyl oxalate can yield keto-esters and symmetric or asymmetric ketones.     

Fluoro-ketones VIII. Synthesis of some fluoroquinoxaline compounds from fluoroketones

The reaction between a perfluoroalkylether ,β-diketone or perfluoroalkyletherketoester and o-phenylenediamine yielding quinoxaline compounds was studied in detail. The various intermediate compounds leading to the formation of the quinoxalines were examined by NMR, MS, GC/MS and IR. 2,3-Perfluoroalkylether substituted quinoxaline is the major product of the reaction. In addition however, the formation of a minor product 3-perfluoro-alkylether-2(1H)-quinoxalinone, indicates an alternate reaction path.     

Pyrimidine derivatives. VI. Synthesis of mono-, di-, tri-, and tetrabromo-substituted pyrimidine derivatives

The following bromo-2,4(1H,3H)-pyrimidinediones possessing a bromo substituent at the 5-position and side chains at the 1- and 6-positions were prepared. The three types of mono-bromo derivatives are: 1-(bromoalkyl)-3,6-dimethyl- 3a-d , 5-bromo-3,6-dimethyl-1-(hydroxyalkyl)- 4a-d , and 1-(acetoxyalkyl)-5-bromo-3,6-dimethyl-2,4(1H,3H)-pyrimidinediones 11a-d . The three types of dibromo derivatives are: 5-bromo-1-(bromoalkyl)-3,6-dimethyl- Sa-d , 1-(acetoxyalkyl)-5-bromo-6-bromomethyl- 8a, 8c , and 8d , and 5-bromo-6-bromomethyl 1-(hydroxyalkyl)-2,4(1H,3H)-pyrimidinediones 9a, 9c , and 9d . Likewise one group of tribromo and one group of tetrabromo derivatives are: 5-bromo-1-(bromoalkyl)-6-bromomethyl -7a-d and 5-bromo-1-(bromoalkyl)-6-dibromomethyl-2,4(1H,3H)-pyrimidinediones 6a-d .     

Synthesis of di- and tetrahydropyrroles.

It was established by means of PMR spectroscopy that the ring-chain tautomeric equilibrium in solutions of 2,3,3-trimethyl-2-hydroxy-5-pyrrolidone and its N-substituted erivatives is shifted exclusively or primarily to favor the cyclic form and that the nature of the solvent has little effect on the position of the equilibrium. An increase in the temperature or the electron-acceptor character of the substituent attached to the nitrogen atom promotes an increase in the percentage of the open forms. The time required to establish the tautomeric equilibrium was determined.See [1] for communication XI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 787–791, June, 1975.     

Fluoro-ketones. III. Synthesis of aryl perfluoroalkylether ketones by the Friedel-Crafts acylation

The first successful application of aliphatic perfluoroacid halides containing an ether function, in the Friedel-Crafts acylation is reported.     

Synthesis of perfluoro[2.2]paracyclophane

A synthesis of perfluoro[2.2]paracyclophane has been sought ever since the partially fluorinated octafluoro[2.2]paracyclophane (AF4) was prepared and its chemistry studied. This compound has now been prepared in 39% yield from the precursor, 1,4-bis(chlorodifluoromethyl)-2,3,5,6-tetrafluorobenzene by its reaction with Zn when heated in acetonitrile at 100 degrees C. Two preparations of the precursor, first from 1,4-dicyano-2,3,5,6-tetrachlorobenzene and an improved method beginning from 1,2,4,5-tetrachlorobenzene, are also described as are key comparisons to our related synthesis of AF4.     

Bridged ferrocenes—VI Synthesis and stereochemistry of [1,1]ferrocenophanes

Synthetic routes to compounds of the [1.1]ferrocenophane class have been devised making use of fulvene and acid chloride precursors and the parent compound has been prepared by direct synthesis. The bridged ferrocenes obtained by these different approaches have been chemically interrelated and their structure and stereochemistry have been investigated through study of their spectral properties. Sodamide promotes intramolecular cyclisation of 1,1′-bis(-cyclopentadienylideneethyl)ferrocene to a [3]ferrocenophane derivative.     

Synthesis of benzimidazoles from 1,1-dibromoethenes

A mild and efficient method for the preparation of substituted benzimidazoles from 1,1-dibromoethenes and o-diaminobenzenes is described. The reaction employs DABCO as the base and NMP as the solvent. A variety of substitutions on both 2-aryl-1,1-dibromoethenes and o-diaminobenzenes are tolerated. This new procedure is carried out under mildly basic conditions, which may provide a complementary route to the existing preparations of benzimidazoles.     

Fluoro-ketones IV. Synthesis of phenylperfluoroalkyl ketones - mechanism of reaction between phenyllithium and fluoroesters

Although fluorine containing ketones (R_fC(O)R_f and R_fC(O)R, R_f = perfluoroalkyl) have been prepared from the reaction between organolithium reagents and perfluoroalkyl esters, the reaction has not found general applicability. Variable yields of ketones and co-production of secondary and tertiary alcohol by-products have in most instances been experienced. We have examined in more detail the factors e.g., temperature, mode of addition and perfluoroalkyl ester structure which influence ketone product and by-products formation. By controlling experimental conditions excellent yields of C₆H₅C(O)R_f compounds can be attained. A lithium salt of a hemiketal (II) has been isolated and shown to be the active intermediate in the production of the ketone. The stability of the salt and its potential reaction with the solvent dictates the type of reaction products. Low temperature favors stability of the lithium salt of the hemiketal whereby high yields of ketones are produced on hydrolysis.     

Synthesis of di- and tetrahydropyrroles

A method for the synthesis of 2,3,3-trimethyl-2-hydroxy-5-pyrrolidone has been developed. 3,3-Dimethyl-2-methylene-5-pyrrolidone is initially formed during its thermolysis and then readily dimerizes. 2,3,3-Trimethyl-2-cyano-5-pyrrolidone was synthesized by the reaction of 2,3,3-trimethyl-2-hydroxy-5-pyrrolidone with potassium cyanide.See [1] for communication VII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1190–1193, September, 1971.     

Synthesis of perfluoro(polyether) difunctional compounds

Omega-iodoperfluoro(polyether) esters IR_fOR_fCO₂R have been synthesized by two procedures. These iodoesters have been reacted via zinc coupling reactions to yield alpha, omega-perfluoro(polyether) diesters. The diesters serve as convenient starting materials for the synthesis of a variety of other difunctional compounds of high molecular weight and exhibiting a variation of oxygen-carbon ratio.     

Synthesis and characterization of perfluoro quaternary ammonium anion exchange membranes

In this study, new alkaline exchange membranes were prepared from the perfluorinated 3M ionomer with various quaternary ammonium cations attached with sulfonamide linkage. The degree of functionalization varied depending on the cation species, resulting in different ion exchange capacities (IECs), 0.33–0.72 meq g⁻¹. There was evidence of polymer degradation when the films were exposed to hydroxide, and hence all membrane characterization was performed in the chloride form. Conductivity was dependent on cation species and IEC, E_a = 36–59 kJ mol⁻¹. Diffusion of water through the membrane was relatively high 1.6 × 10⁻⁵ cm² s⁻¹ and indicated restriction over a range of diffusion times, 6–700 ms. Water uptake (WU) in the membranes was generally low and the hydration level varied based on cation species, λ = 6–11. Small-angle scattering experiments suggested ionic aggregation, 37–42 Å, independent of cation species but slight differences in long-range order with cation species. © 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1761–1769, 2013     

Synthesis of 1,1-bis-phosphorus compounds from organoboranes

The facile synthesis of various P-C-P compounds is described, based on the reaction of phosphorus carbenoids with organoboranes, followed by reaction with phosphorus electrophiles. Using this approach, symmetrically and differentially substituted 1,1-bisphosphorus compounds can be obtained in good yields. A number of novel P-C-P motifs are described for the first time.     

Synthesis of low molecular weight perfluoro oxymethylene vinyl ethers

Perfluoro oxymethylene vinyl ethers have been formed by a multi-step synthesis. The key intermediates are low molecular weight perfluoropolyether (PFPE) fluoroformates CF₃O(CF₂O)_nCOF (I) n=1-6 obtained from the photo-oxidation of perfluoro propene (HFP) in perfluorohexane. Under certain conditions the light-mediated fluorination of PFPE fluoroformates (I) gives PFPE hypofluorites CF₃O(CF₂O)_nCF₂OF (II), which can be added to sym dichlorodifluoroethene to form the dichloro adduct CF₃O(CF₂O)_nCF₂OCFClCF₂Cl (III) which, after dechlorination, gives the desired vinyl ethers CF₃O(CF₂O)_nCF₂OCFCF₂ (IV). Every reaction step has to be properly controlled as far as the reaction variables are concerned. A mechanistic scheme is presented that is consistent with the observed experimental data.     

Synthesis of α-arylnaphthalenes from diphenylacetaldehydes and 1,1-diphenylacetones

Condensation of diphenylacetaldehydes and 1,1-diphenylacetones with malonodinitrile and cyclization of obtained aryl-ylidenemalonodinitriles in concentrated sulfuric acid leads to 1-amino-4-arylnaphthalene-2-carbonitriles. The benzannulation reaction is accompanied by a quasi-aromatic rearrangement. Preliminary tests of some synthesized aminonitriles have revealed their considerable biological activity against phytopathogenic fungi.     

Fluoro-ketones. I reactions of hydrocarbon grignards with perfluoroalkylacid fluorides

The reaction between Grignard reagents and perfluoroacid fluorides provides a convenient synthesis procedure for ketones R_fOR_fC(O)R′, where R_fOR_f is perfluoroalkylether group and R' is either an aromatic or aliphatic group. Reaction temperature is an important factor in producing higher yields of ketones. Meta and para-bromophenyl Grignard reagents, which thus far have not been prepared as pure mono Grignards, present secondary competing reactions which detract from their synthetic utility.     

Synthesis of some di- and trifluoro quinoxaline and dioxine derivatives from pentafluoropyridine

Novel [6,6,6] ring fused tricyclic systems can be readily synthesized in one-pot annulation reaction of pentafluoropyridine or 4-phenylsulfonyl tetrafluoropyridine with appropriate difunctional nitrogen and oxygen nucleophiles attached to aromatic rings. Reaction of 4-phenylsulfonyl tetrafluoropyridine with 2,6-diaminopyridine gave [6,5,6] ring fused systems arising from a tandem S_NAr and cyclisation process. From this investigation, di- and trifluorinated quinoxaline and dioxine scaffolds were synthesized.