Reactions of β-alkoxyvinyl trihalogenomethyl ketones with triethyl phosphite

The Perkow reaction of triethyl phosphite and β-alkoxyvinyl trihalogenomethyl ketones, which have common acyclic or cyclic structural fragment: -O-CC-C(O)CX₂Cl, yielded dienyl phosphates: -O-CC-C[OP(O)(OEt)₂]CX₂ where X = F or Cl, whereas γ-bromo-β-methoxy-α,β-unsaturated trifluoromethyl ketone CF₃C(O)CHC(OMe)CH₂Br gave diene CF₃C[OP(O)(OEt)₂]CH-C(OMe)CH₂.     

A ruthenium(II) allenylidene complex with a 4,5-diazafluorene functional group: A new building-block for organometallic molecular assemblies

The synthesis of the new ruthenium(II) allenylidene complex [ClRu(dppe)₂CCC₁₁H₆N₂][OTf] (4) (dppe = 1,2-bis(diphenylphosphino)ethane) terminated with a 4,5-diazafluorene ligand is reported. Further coordination of that metal allenylidene to ruthenium and rhenium moieties leads to the bimetallic adducts [ClRu(dppe)₂CCC₁₁H₆N₂{Ru(bpy)₂}][B(C₆F₅)₄]₃ (5a), [ClRu(dppe)₂CCC₁₁H₆N₂{Ru(^tBu-bpy)₂}][PF₆]₃ (5b) and [ClRu(dppe)₂CCC₁₁H₆N₂{Re(CO)₃Cl}][OTf] (6). Their optical and electrochemical properties show that the allenylidene moiety is an attractive molecular clip for the access to larger original redox-active homo/heteronuclear multi-component supramolecular assemblies. The X-ray crystal structure of the allenylidene metal building block is also described.     

Thermal gas-phase reaction of perfluorobuta-1,3-diene with NO2

The reaction of NO₂ with perfluorobuta-1,3-diene, CF₂CFCFCF₂ (C₄F₆), has been studied at 312.9, 323.0, 333.4, 396.0 and 418.0 K, using a conventional static system. The products formed in the temperature range 312.9-333.4 K were CF₂CFCF(NO₂)CF₂(NO₂) (I), CF₂(NO₂)CFCFCF₂(NO₂) (II), CF₂CFCF(NO₂)C(O)F (III) and CF₂(NO₂)CFCFC(O)F (IV) and FNO. The formation of these compounds was detected performing infrared and Raman spectra. The infrared spectrum shows a band at 1785 cm⁻¹, characteristic to the terminal -CFCF₂ group and the Raman spectrum shows a band located at 1733 cm⁻¹, corresponding to -CFCF- group. It indicates, that in this temperature range, NO₂ attacks initially only one double bound of CF₂CFCFCF₂. Since the intermediate radical CF₂CFCFCF₂(NO₂) formed in this process is allylic in nature, so there is no isomerization involved in this process, but rather the allylic radical is able to add the second NO₂ either to CF₂ or CFCF₂(NO₂) end, forming the corresponding products. At 396.0 and 418.0 K different products were observed: CF₂(NO₂)CF(NO₂)C(O)F (V), NO, CF₃C(O)F, C(O)F₂ and traces of epoxide of tetrafluoroethene, showing that, at these temperatures, both double bonds are attacked by NO₂ and detachment of CF₂ group is produced. The mechanisms consistent with experimental results in the temperature range 312.9-333.4 and at 396.0 and 418 K are proposed.     

Nickel alkynyl and allenylidene complexes: Synthesis and properties

Copper-catalyzed reaction of [Cp(PPh₃)NiCl] with the terminal alkynes H-CC-C(O)R (R = O-Menthyl, NMe₂, Ph) yields the alkynyl complexes [Cp(PPh₃)Ni-CC-C(O)R]. Subsequent O-methylation with either [Me₃O]BF₄ or MeSO₃CF₃ affords cationic allenylidene complexes, [Cp(PPh₃)NiCCC(OMe)R]⁺X¯ (X = BF₄, SO₃CF₃). N-Alkylation of Cp(PPh₃)Ni-pyridylethynyl complexes likewise gives cationic allenylidene complexes. [Cp(PPh₃)Ni-CC-C(CH)₄N] adds BF₃ at nitrogen. Modification of the ligand sphere in these nickel allenylidene complexes is possible by replacing PPh₃ by PMe₃ in the alkynyl complex precursors. The first allenylidene(carbene)nickel cation, [Cp(SIMes)NCCC(OMe)NMe₂]⁺, is accessible by successive reaction of [Cp(SIMes)NiCl] with H-CC-C(O)NMe₂ and [Me₃O]BF₄. By the analogous sequence an allenylidene complex containing the chelating (diphenylphosphanyl)ethylcyclopentadienyl ligand can be prepared. DFT Calculations were carried out on the allenylidene complex cation [Cp(PPh₃)NiCCC(OMe)NMe₂]⁺ and on its precursor, the alkynyl complex [Cp(PPh₃)Ni-CC-C(O)NMe₂]. Based on the spectroscopic data and a X-ray structure analysis the bonding in the new nickel allenylidene complexes is best represented by several resonance forms, an alkynyl resonance form considerably contributing to the overall bond.     

Polyfluoroaromatic compounds with a NCClR group—a reactive type of polyfluoroarene

This review deals with syntheses and reactivity of polyfluoroarenes with a NCClR group (including those with RCl). The most promising and convenient methods of synthesis of these type compounds are based on co-pyrolysis reactions of low-basic polyfluoroaromatic amines with RCCl₃ type derivatives and the interaction of such amines and polyfluoroaromatic hydrazines with RCX₃ (XCl,F) compounds in the presence of AlCl₃ at moderate temperature; they have no analogues in the nonfluorinated series. Reactions with different nucleophilic reagents, the formation of electrophilic intermediates of the nitrilium cation type and reactions of the latter with aromatic and fluoroaromatic hydrocarbons, amines, and compounds with CN, C≡N and CO multiple bonds are described. It is shown that polyfluoroaromatic compounds with a NCClR group are promising precursors for syntheses of a wide range of compounds of various classes, including heterocyclic derivatives.     

Iodo-alkynyl- and iodo-butadiynyl-ruthenium complexes

Addition of [I(py)₂]BF₄ to Ru(CCH)(dppe)Cp∗ gave the iodovinylidene [Ru(CCHI)(dppe)Cp∗]BF₄1, which could be deprotonated to Ru(CCI)(dppe)Cp∗ 2. The attempted preparation of Ru(CCCCI)(dppe)Cp∗, followed by derivatisation with tcne, gave the dienynyl Ru{CCC[C(CN)₂]CIC(CN)₂}(dppe)Cp∗ 3. The Pd(0)/Cu(I)-catalysed reaction of 3 with Ru{CCCCAu(PPh₃)}(dppe)Cp∗ afforded Ru{CCCC(CN)₂CC(CN)₂Au(PPh₃)}(dppe)Cp∗ 4 by formal replacement of I⁺ by [Au(PPh₃)]⁺. XRD structures of 1-4 are reported.     

Direct addition of supercritical alcohols, acetone or acetonitrile to the alkenes without catalysts

The reactions of the alkenes with supercritical organic compounds under non-catalytic conditions were investigated. The H and CR₂OH, CH₂COCH₃ or CH₂CN of supercritical alcohols (CHR₂OH), acetone (CH₃COCH₃) or acetonitrile (CH₃CN) added to the CC bonds of alkenes form C-C bonds between the α-carbons of the supercritical organic compounds and the sp² carbons of the alkenes.     

Functionalized fluoroalkyl and alkenyl silanes: Preparations, reactions, and synthetic applications

Preparations, reactions, and synthetic applications of functionalized fluoroalkyl and alkenyl silanes have been summarized. This review focuses mainly on the chemistries of (1) 1-substituted difluoromethylsilanes (XCF₂SiR₃), (2) 1-substituted 2,2-difluorovinylsilanes (CF₂CXSiR₃), (3) trifluoroisopropenyl, trifluoroacetimidoyl, and trifluoroacetyl silanes [CF₃C(SiR₃)X, XCH₂, NAr, O] and (4) other fluorinated alicyclic silanes.     

A well feasible and general route to (organoethynyl)difluoroboranes, RHCCBF2, and their perfluorinated analogues, RFCCBF2

A representative series of (organoethynyl)difluoroboranes RCCBF₂ (RC₄H₉, (CH₃)₃C, CF₃, C₃F₇, (CF₃)₂CF, CF₃CFCF, C₄F₉CFCF, C₆F₅) was prepared by abstraction of fluoride from the corresponding K[RCCBF₃] salts with BF₃ in appropriate solvents (1,1,1,3,3-pentafluoropropane, 1,1,1,3,3-pentafluorobutane, or dichloromethane).     

Hyperpolarizability of donor-acceptor azines subject to push-pull character and steric hindrance

The push-pull character of two series of donor-acceptor azines has been quantified by ¹³C, ¹⁵N chemical shift differences of the partial C(1)N(1) and N(2)C(2) double bonds in the central linking C(1)N(1)-N(2)C(2) unit and by the quotient of the occupations of the bonding π and anti-bonding π^∗ orbitals of these bonds. Excellent correlation of the latter push-pull parameter with the corresponding bond lengths d_CN strongly recommend both the occupation quotients π^∗/π and the corresponding bond lengths as reasonable sensors for quantifying the push, pull character along the CN-NC linking unit, for the donor-acceptor quality of the two series of azines and for the molecular hyperpolarizability ß₀ of these compounds. Within this context, reasonable conclusions concerning the interplay of steric hindrance in the chromophore, push-pull character and hyperpolarizability of the azines and their application as NLO materials will be drawn.     

Synthesis and characterisation of a diphosphaalkene, a diphosphaalkyne and the first diphosphavinyl lithium complex

The preparation and characterisation of a diphosphaalkene, (Me₃Si)PC(OSiMe₃){C(C₂H₄)₃C}C(OSiMe₃)P(SiMe₃), and the second example of a diphosphaalkyne, PC{C(C₂H₄)₃C}CP, are described. In addition, the reaction of another diphosphaalkyne, PC{C(C₆H₄)₃C}CP, with MeLi/LiBr in the presence of tmeda has given the first diphosphavinyl lithium complex, [MePC{Li₂Br(tmeda)₂}{C(C₆H₄)₃C}C{Li₂Br(tmeda)₂}PMe], which is stable at room temperature and has been crystallographically characterised.     

N-Perfluoroalkylsulfonylimido derivatives of arenecarboxylic acid amides and their oxidative aza Hofmann rearrangement

The analogues of carboxamides in which the sp²-hybridized oxygen atom is replaced by more electron-withdrawing groups, NSO₂CF₃ and NSO₂C₄F₉, have been synthesized. The resulting N-perfluoroalkylsulfonyl arenecarboxamidines ArC(NSO₂R_f)NH₂ (R_f = CF₃, C₄F₉) undergo an oxidative Hofmann-type rearrangement to the corresponding carbodiimides ArNCNSO₂R_f under the action of (diacyloxyiodo)arenes. Rearrangement of related compounds ArC(NSO₂R)NH₂ (R = CH₃, Ph) containing fluorine-free substituents at the sulfonyl group also occurs in similar conditions. It was found that the reactivity of amidines rises with the increasing electron-withdrawing ability of the substituent R.     

Further reactions of some bis(vinylidene)diruthenium complexes

Whereas {Ru(dppm)Cp*}₂(μ-CCCC) (2) is the only product formed by deprotonation of [{Ru(dppm)Cp*}₂{μ(CCHCHC)}]⁺ with dbu, a mixture of 2 with Ru{CCCHCH(PPh₂)₂[RuCp*]}(dppm)Cp* (3) and {Cp*Ru(PPh₂CHCCH-)}₂ (4) is obtained with KOBu^t. A similar reaction with [{Ru(dppm)Cp*}₂{μ(CCMeCMeC)}]⁺ (5) gave Ru{CCCMeCH(PPh₂)₂[RuCp*]}(dppm)Cp* (6). X-ray structures of 4, 5 and 6 confirm the presence of the 1-ruthena-2,4-diphosphabicyclo[1.1.1]pentane moiety, which is likely formed by an intramolecular attack of the deprotonated dppm ligand on C(1) of the vinylidene ligand. Protonation of {Ru(dppe)Cp*}₂(μ-CCCC) (8-Ru) regenerates its precursor [{Ru(dppe)Cp*}₂{μ(CCHCHC)}]²⁺ (7-Ru). Ready oxidation of the bis(vinylidene) complex affords the cationic carbonyl [Ru(CO)(dppe)Cp*]PF₆ (9) (X-ray structure).     

Reaction of trifluoromethylated β-alkoxyenones with tris(trimethylsilyl) phosphite: A temperature influence on regioselectivity

The interaction of tris(trimethylsilyl) phosphite (TMSO)₃P and E-trifluoromethyl-β-alkoxyenones CF₃C(O)CHCHOEt and CF₃C(O)CHC(OMe)Me yielded mixtures of E-1,2- and Z-1,4-adducts, CF₃C(OTMS)[P(O)(OTMS)₂]CCH(OAlk)R 2 and CF₃(OTMS)CCHCR(OAlk)[P(O)(OTMS)₂] 3 where R and Alk = H and Me, or both Me. Conversion of these 1,2-adducts to 1,4-isomers was effected by increased temperature or by exposure to more tris(trimethylsilyl) phosphite. Acid hydrolysis of 2b (R and Alk = Me) gave ketophosphonic acid CF₃C(OH)[P(O)(OH)₂]CH₂COMe in 88% yield, whereas hydrolysis of 2a (R = H and Alk = Et) with KOH in methanol gave CF₃C(OH)[P(O)(OK)₂]CHCHOEt in 37% yield. Acid hydrolysis of 3a (R = H and Alk = Et) and 3b (R and Alk = Me) gave phosphonic acid CF₃C(OH)₂CHCHP(O)(OH)₂ in 82% yield and trifluoromethylated 1,2λ⁵σ⁴-oxaphosphol-3-en.     

Organometallic chemistry and catalysis on gold metal surfaces

As in transition metal complexes, CN-R ligands adsorbed on powdered gold undergo attack by amines to give putative diaminocarbene groups on the gold surface. This reaction forms the basis for the discovery of a gold metal-catalyzed reaction of CN-R, primary amines (R′NH₂) and O₂ to give carbodiimides (R′-NCN-R). An analogous reaction of CO, RNH₂, and O₂ gives isocyanates (R-NCO), which react with additional amine to give urea (RNH)₂CO products. The gold-catalyzed reaction of CN-R with secondary amines (HNR′₂) and O₂ gives mixed ureas RNH(CO)NR′₂. In another type of gold-catalyzed reaction, secondary amines HN(CH₂R)₂ react with O₂ to undergo dehydrogenation to the imine product, RCHN(CH₂R). Of special interest is the high catalytic activity of gold powder, which is otherwise well-known for its poor catalytic properties.     

Synthesis of new pentafluorosulfanylacrylates (F5SCHCHCHO, F5SCHCHCN, F5SCHCHCOOCH3) and use of them as dienophiles in Diels-Alder reaction

New pentafluoro-λ⁶-sulfanylacrylates (F₅SCHCHCHO, F₅SCHCHCN, F₅SCHCHCOOCH₃) were synthesized by a convenient and efficient method. These compounds are useful as intermediates in the preparation of pentafluoro-λ⁶-sulfanyl-containing cyclic and heterocyclic Diels-Alder cycloadducts.     

Reactivity of Ph3PNLi towards P and P electrophiles

A study of the reactivity of Ph₃PNLi towards phosphorus electrophiles allowed us to develop a general method to isolate, or cleanly generate in situ, a broad family of polyphosphinimines displaying PN-P bonds. A preliminary application of this methodology is presented here with the synthesis of various Schwesinger-type bases by a simple new procedure employing Ph₃PNLi.     

The first evidence for a transient stibaallene ArSbCCR2

Dechlorofluorination of ArSb(F)-C(Cl)CR₂ (CR₂ = fluorenylidene, Ar = 2,4,6-tri-tert-butylphenyl) by tert-butyllithium afforded a 3,4-bis(fluorenylidene)-1,2-distibacyclobutane. The formation of the latter probably involves the transient stibaallene ArSbCCR₂ followed by a head-to-head dimerization via two SbC double bonds. Molecular orbital calculations at the ab initio and DFT levels support the head-to-head dimerization of ArSbCCR₂ with the formation of a 1,2-distibacyclobutane.     

Ferrole-type compounds containing thiophenic or thiepinic rings in the 3,4-positions of the metallacycle

The new ferrole Fe₂(CO)₆[μ-η²,η⁴-(Fc)CC{C(H)C(R)S}CC(SiMe₃)] [R = SiMe₃ (1) and R = Fc (2)] and ruthenoles Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC{SC(Fc)C(H)}CC(Fc)] 3 and Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC(SCCFc)C(H)C(Fc)] 4, have been obtained from the reactions of M₃(CO)₁₂ (M = Fe, Ru) and FcCCSCCSiMe₃ through S-C bond activations and C-C coupling reactions. Thermolysis of Ru₂(CO)₆[μ₃-η²,η⁴,η³-(Me₃Si)CC{SC(Fc)C(SCCSiMe₃}Ru(CO)₃}CC(Fc)] alone and in the presence of HCCFc, yielded the compounds Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC{SC(Fc)C(SCCSiMe₃)}CC(Fc)] 5 and Ru₂(CO)₆[μ-η²,η⁴-(Me₃Si)CC{SC(Fc)C(SCCSiMe₃)C(H)C(Fc)}CC(Fc)] 6, respectively. The crystal structures of the compounds 1, 3, 4 and 6 are reported.