Synthesis of 5-azido-4-cyanoimidazole and its reaction with active methylene compounds

Diazotisation of 1-acetamido-5-amino-4-cyanoimidazole 2 using sodium nitrite in aqueous acetic acid gave 5-azido-4-cyanoimidazole 3 in 94% yield. Reaction of 3 with active methylene compounds R¹COCH₂R² [R¹ = Me, R² = COMe; R¹ = Me, R² = COPh; R¹ = Me, R² = COOEt] or malononitrile in the presence of base led either to imidazo[5,1-d][1,2,3,5]tetrazepines 6 and 8 or to imidazolyltriazoles 5 , 7 and 9 , depending on the reaction conditions. Tetrazepine 6c evolves to triazole 7c or 5c respectively in the presence of acid or by further treatment with base. Purine 10 was also isolated in the reaction of 3 with malononitrile.     

Tautomeric behavior of 3-(arylhydrazono)methyl-2-oxo-1,2-dihydroquinoxalines between the hydrazone imine and diazenyl enamine forms in acidic media. Solvent and substituent effects

The 3-(arylhydrazono)methyl-2-oxo-1,2-dihydroquinoxalines 1a-h and 2a-e showed tautomeric equilibria between the hydrazone imine A and diazenyl enamine B forms in a series of mixed trifluoroacetic acid/dimethyl sulfoxide media. The substituent and solvent effects on the tautomer ratios of A to B in a series of mixed media were studied for compounds 1a-h and 2a-e by the nmr spectroscopy. In compounds 1a-h and 2a-e , the ratios of the tautomer B gradually increased with elevation of acid concentration, and the tautomer B exclusively existed in trifluoroacetic acid media. The various acid concentrations (C v/v%, C' mol/1) giving the 1:1 tautomer ratios [C(A:B = 1:1), C'(A:B = 1:1)] were obtained from all compounds (Figures 1–13), and the linear correlation of the Hammett σ_p values with the log C'(A:B = 1:1) values were observed for compounds 1a-h. The larger Hammett σ_p values brought about the larger acid concentrations C(A:B = 1:1) in compounds 1a-h and 2a-e , indicating that the higher acid concentration was required for the stabilization of tautomer B possessing the electron-withdrawing p-substituents R¹, which weakened the basicity of the azo nitrogen atom. Moreover, the ester group R² of compounds 2a-e was found to decrease the electron density of the azo nitrogen atom, since the acid concentration C(A:B = 1:1) of compound 2c (R¹ = H, R² = COOMe, σ_p = O) was 52%, whose value was larger than that of compound 1b (R¹ = CN, R² = H, σ_p = 0.66) [C(A:B = 1:1) = 42%].     

REACTIONS OF A PHOSPHORANIMINE ANION WITH SOME ORGANIC ELECTROPHILES

Abstract

The reactions of a variety of electrophiles with the N-silyl-P-trifluoroethoxyphosphoranimine anion Me₃Sin°P(Me)(OCH₂CF₃)CH^? ₂ (1a), prepared by the deprotonation of the dimethyl precursor Me₃SiN[dbnd]P(OCH₂CF₃)Me₂ (1) with n-BuLi in Et₂O at-78°C, were studied. Thus, treatment of 1a with alkyl halides, ethyl chloroformate, or bromine afforded the new N-silylphosphoranimine derivatives Me₃SiN[dbnd]P(Me)(OCH₂CF₃)CH₂R [2: R = Me, 3: R = CH₂Ph, 4: R = CH[sbnd]CH₂, 5: R = C(O)OEt, and 6: R = Br]. In another series, when 1a was allowed to react with various carbonyl compounds, 1,2-addition of the anion to the carbonyl group was observed. Quenching with Me₃SiCl gave the O-silylated products Me₃SiN[dbnd]P(Me)(OCH₂CF₃)CH₂°C(OSiMe₃)R¹R² [7: R ¹ = R ² = Me; 8: R ¹ = Me, R ² = Ph; 9: R¹ = Me, R ² = CH[sbnd]CH₂; and 10: R ¹ = H, R ² = Ph]. Compounds 2–10 were obtained as distillable, thermally stable liquids and were characterized by NMR spectroscopy (¹H, ¹³C, and ³¹P) and elemental analysis.     

Effect of Microwave Irradiation on Reaction of Arylaldehyde Derivatives with Some Active Methylene Compounds in Aqueous Media

Abstract

The effect of microwave irradiation on the condensation reactions of arylaldehydes 1 and active methylene compounds 2 in aqueous media was studied and compared with “classical” conditions. The results show that the condensation was carried out only under microwave irradiation in the presence of ammonium chloride as a catalyst, followed by dehydration, to afford (E)‐olefins 3. The protocol was used to synthesize coumarins by a condensation reaction of salicylaldehyde or its derivatives with various derivatives of ethylacetate 5 (e.g., R³CH₂CO₂Et; R³: CO₂Et, CO₂Me, COMe, CN) in high yields. These investigations will contribute to the development of environmentally friendly and inexpensive processes in organic synthesis.     

13C NMR spectra of coordinated propargyl cations [Cp2Mo2(CO)4(μ-η2,η3-(HC≡CCR1R2)]+ BF4/?

A strong deshielding effect is observed for the carbon signal of carbocation center (C⁺) in the ¹³C NMR spectra of coordinated propargyl cations [Cp₂Mo₂(CO)₄(μ-η²,η³-(HC≡CCR¹R²)]⁺ BF₄⁻ (R¹ = R² = H) 1, (R¹ = Me, R² = H) 2, and (R¹ = R² = Me) 3 when hydrogen is replaced by methyl; the effect increases with the Mo-C⁺ distance (75.37, 98.3, and 148.68 ppm for compounds 1, 2, and 3, respectively). This indicates that the back-donation of electron density from the metal onto the ligand makes a substantial contribution to the stabilization of these cations. Original Russian Text ? I.V. Barinov, V.A. Chertkov, 2009, published in Vestnik Moskovskogo Universiteta. Khimiya, 2009, No. 1, pp. 29–34.     

Studies on the Synthesis and Perporties of Ethyl-N-Alkylphosphoro(Thioureido)Thioates

Abstract

O-Ethyl-N-alkylphosphoro(thioureido)thioates(II) were synthesized by the addition of O-ethyl-N-alkylphosphor-isothiocyanatidothioates(I) with corresponding alkyl or aryl amines, in which R=C¹, -C₃, R¹, R²=H, alkyl or aryl. Their structures were confirmed by IR, ¹H NMR, MS and elemental analysis. The results of bioassay showed that they had fairly good fungicidal and herbicidal activities. When II(R¹=H,R²=i-Pr,Ph,aryl etc.) reacted with chloroacetyl chloride, the compounds III were given.     

Polarity and Conformatios of Phosphorylethylenes and Phosphorylacetates in Solution

Abstract

A series of derivatives R¹R²P(X)R³, where R¹=R²=Ph. R³= -CH=CH-Me, X=O(I); R¹=Me, R²=Ph, R³= -CH=CH₂, X=O(II); R¹=R²=Ph, R³= -CH=CH₂, X=Se(III) and R¹R²P(O)-CH₂C(O)OX, where R¹=Ph, R²= -CH=CH₂, X=Ment?(IV); R¹=Ph-2-OMe, R²=Ph, X=Ment?(V); R¹=R²=CH₂Ph, X=Et(I), were investigated by means of dipole moments method. The problem of conjugation in phosphorylethylenes and conformation behaviour of phosphorylacetates was considered. DM (exp.) of (I-IV), determined in CC1₄ solution are 4.48(I), 4.27(II), 4.97(III), 4.21(IV), 5.21(V) and 4.02 D (VI). The intramolecular electronic interactions of phosphoryl group with unsaturated fragment did not displays in polarity properties of compounds (I-III). The experimental dipole moments of derivatives (I-III) are equal to the calculated values of DM. DM (IV-VI) is very sensitive to orientation of the P=O and C=O polar bonds. Because DM (exp.) of these compounds very sensitive to its orientation. DM (calc.) for cis- and trans- orientation of P=O and C=O dipoles are really different, that allows to drow the conclution that, in the contrast to the crystal state, the corresponded dipoles prefer an anti array in solution.     

Addition de l'acide thiocyanique aux acetyleniques a l'aide de hg(II) II - Obtention d'isothiocyanates vinyliques par mercuration-protodemercuration

Thiocyanic acid HSCN is added to some acetylenic compounds R¹-C&² through a two-step one-pot procedure wich involves, first, the generation in CH₂Cl₂ of β-thiocyanato and/or β-isothiocyanato alkenyl mercuric coupounds R¹-C (SCN)=CR²-Hg- by addition of mercury (II) thiocyanate Hg(SCN)₂ to R¹-C&² then the substitution of mercury by hydrogen through acidic treatment. In proper conditions of stoechiometry and reaction time the process is tharmodynamically controlled and thus allows to obtain vinyl isothiocyanates R¹-C(-NCS)CHR² even when the isomeric vinyl thiocyanates are kinetically favoured. Preparation of 3,3- dimethyl 2-isothiocyanato 1-thiocyanato 1-butene is also reported.     

Synthesis,structure and isomerism of “three-bridge” exo-nido-osmacarborane clusters

The reaction of OsCl₂(PPh₃)₃ with [nido-7-R¹-8-R²-C₂B₉H₁₀]K⁺ produced a series of new exo-nido-osmacarborane complexes exo-nido-5,6,10-[Cl(Ph₃P)₂Os]-5,6,10-(-H)₃-10-H-7-R¹-8-R²-7,8-C₂B₉H₆ (1: R¹ = R² = H; 2: R¹ = R² = Me; 3: R¹ = R² = PhCH₂; 4: R¹ + R² = 1,2-C₆H₄(CH₂)₂; 5: R¹ = H, R² = Me) in which the osmium-containing group is linked to the nido-carborane ligand through three two-electron three-center bonds. Compounds 1—5 are formed as mixtures of symmetric (a) and asymmetric (b) isomers; pure symmetric isomers 2a and 4a were isolated by fractional crystallization, and the mixture of isomers 3a, was quantitatively separated into individual compounds 3a and 3b by column chromatography on silica gel. Detailed analysis of the ³¹P{¹H}, ¹H, ¹¹B NMR spectra of 1a,b—5a,b and 2D ¹H-¹H{¹¹B} and ¹¹B{¹H}-¹¹B{¹H} NMR spectra of 3a and 3b was performed. The structures of isomers 2a and 4a were confirmed by an X-ray diffraction study. According to the NMR and X-ray diffraction data, the isomerism of exo-nido-complexes 1a,b—5a,b is actually the cis—trans-isomerism of ligand arrangement in the octahedral coordination of the Os atom.     

Interaction of Tris(3-Hydroxymethyl)Phosphine with Cinnamic Acids

Abstract

Phosphonium zwitterions of the known type R₃P⁺CH(Ar)CH₂CO₂ ^? (II) are obtained as a racemic mixture in moderate yield via a 1:1 reaction of cinnamic acids (Ar = phenyl, or substituted phenyl) with [HO(CH₂)₃]₃P in acetone at room temperature under Ar. The products are characterized by elemental analysis, ³¹P{¹H}-, ¹H-, and ¹³C{¹H}-NMR spectroscopies, and mass spectrometry, although they contain a minor coproduct formed via neutralization of the positive and negative charges of II with the respective acid and phosphine reactants (see Experimental Section). In CD₃OD, the monodeuterated salts R₃P⁺CH(Ar)CH(D)CO₂ ^? are formed as a mixture of diastereomers with d.r. values of ～2 to 8, depending on substituent groups present in the organic acid; in these studies, 2-HO-cinnamic acid is the most reactive, and β-methylcinnamic acid is the least reactive.     

Heteroorganic betaines

Photolysis and thermal decomposition of betaines R₃P−CR¹R²−SiR³R⁴−S⁻ (1) follows two main pathways: (a) a Corey—Chaykovsky type reaction with elimination of Ph₃P and generation of silathiirane (2) and (b) a retro-Wittig type reaction accompanied by elimination of R₃P=CR¹R² and generation of silanethione R³R⁴Si=S (3). Highly reactive compounds2 and3 undergo subsequent transformations to give derivatives of tetrahydro-1,4-dithia-2,5-disilin, 1,3-dithia-2,4-disilolane, and phosphonium salts ofsymm-tetraorganodisilthiane dithiolates [Ph₃P⁺CHR¹R²]₂[(R³R⁴SiS⁻)₂S]. The structures of the compounds obtained were established by X-ray diffraction analysis and multinuclear NMR spectroscopy. For part 3, see Ref. 1. The betaines Et₃P⁺CHMeSiMe₂S⁻ and Et₃P⁺CHMeSiPh₂S⁻ with alkyl groups at the phosphorus atom are distinguished by high thermal stability; their spectral characteristics do not change during storage of solutions of these compounds in pyridine-d₅ or metastable solutions in benzene-d₆ for 1–2 years at −20°C in sealed evacuated tubes or on heating (150°C) for 15 h. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1594–1603, September, 2000.     

Steric effect on the formation of columnar phases in β-diketonate copper(II) complexes

A systematic study of the mesomorphic properties of three series of copper(II) complexes based on β-diketonate ligands containing branched side chains is reported. These disc-like compounds have four, six and eight flexible alkoxy side chains appended to the central core, in which two or four side chains were substituted by bulkier secondary alkoxy groups: 1-methylbutyloxy R ' = C₅(2°) or 1-methylheptyloxy R ' = C₈(2°). The mesomorphic results indicated that at least eight side chains are required to form stable columnar mesophases; other compounds with four or six side chains are not mesogenic regardless of the combination of the carbon length on the alkoxy or secondary alkoxy groups of the side chains. The compounds 3 with shorter R ' = C₅(2°) side chains were all non-mesogenic regardless of the carbon length of three alkoxy side chains (R = C₈, C₁₀, C₁₂) used. However, when the longer 1-methylheptyloxy side chain R ' = C₈(2°) was substituted, the compounds 3b-3e with various alkoxy groups (R = C₆, C₇, C₈, C₁₀, C₁₂) exhibited columnar phases. The mesophases were characterized and identified as columnar hexagonal phases (Col_h), as expected, by thermal analysis and optical polarized microscopy. The presence of the introduced secondary alkoxy groups apparently appeared to influence the formation of columnar phases. The clearing points were relatively lower than other similar copper(II) compounds not substituted by secondary alkoxy side chains.     

Formation and Stability of Difluoromethylene Phospho-Raiies,R3P=CF2

Abstract

Carbonyl compounds react with CBr₂F₂ in the presence of phosphanes, RP (R = Ph, NR;), and metals (M = Zn, Cd, Pb) forming geminal difluoroolefins (eq. 1)¹.

R′CHO + CBr₂F₂ + R₃P + M → R′CH=CF₂ + MBr₂ + R₃PO (1)

Without any doubt this reaction has to occur via the intermediate formation of difluoromethylene phosphoranes, which then undergo the Wittig reaction with carbonyl compounds (eq. 2). R₃P=CF₂ + R′CHO → R₃PO + R′CH=CF₂ (2).     

Synthesis of functional polyethylene <Emphasis Type="Italic">via</Emphasis> copolymerization of ethylene and substituted allene using bis(<Emphasis Type="Italic">β</Emphasis>-enaminoketonato)titanium catalysts

Novel copolymerization of ethylene with substituted allenes（CH₂=C = CH—R,1:R = n-butyl,2:R =n-octyl） using bis（β-enaminoketonato）titanium catalysts[PhN = C（R₂）CHC（R₁）O]₂TiCl₂（1a:R₁ = CF₃,R₂ = CH₃;1b:R₁ = Ph,R₂ = CF₃） has been investigated.In the presence of modified methylaluminoxane,these catalysts can copolymerize ethylene with substituted allenes,affording copolymers with unimodal molecular weight distributions and homogeneous compositions.By varying the reaction conditions,the comonomer incorporation can be tuned in the range of 0-3.6 mol%.¹H-NMR spectra reveal that the copolymerization proceeds through 1,2-insertion fashion of allene comonomer exclusively,and the regioselective nature maintains under various reaction conditions.The retained intra-chain double bond can be converted into the epoxy group under mild conditions.     

Imides of 2-Trifluoroacetylphenol and other Trifluoracetic acid Esters: Novel Reactions with Phosphorus(III) Derivates

Abstract

The imido derivates of 2-trifluoroacetylphenol, 1 (R¹=H, Me, iPr) react with the isocyanatophosphites (R²O)₂PNCO, 2 (R²[dbnd]Et, R²-R²[dbnd]CMe₂-CMe₂) to yield the bicyclic compounds 3, wheras in case of 1 (R¹[dbnd](CH₂)₂NMe2) the λ³σ³P compounds 4 are found. The phosphorus(III) chlorides R3PC12 (R³[dbnd]Ph, OEt) and 1 (R¹[dbnd]H, Me) give rise to furnish the tricyclic phosphoranes 5. However with 1 (R¹[dbnd]iPr) phosphite 6 is obtained, which adds hexafluoracetone to give the 1,3,2λ⁵σ⁵-dioxaphospholane 7. 2-(Trifluoracetoxy)pyridine 8. reacts with Tris(trimethylsily1)phosphite to yield the bis(phosph0nate) 10. Some molecular structures are discussed on the basis of x-ray diffraction results.     

Synthesis and Reactivity of some Aromatic Sulfides Substituted by an Ortho-Phosphonyl Group

Abstract

As phosphorus-based members of the biologically relevant thiosalicylic acid, monoesters of ortho-sulfinylated phenylphosphonic acids such as 3 and 4 (series a, R¹=Me; b, R²2-C₆H₄C0₂H) are of special interest. They might act both as potential sources of new anionic bidentate ligands for the synthesis of cisplatin analogues^[1] and as suitable precursors of phosphorus-containing endocyclic sulfoximides and hypervalent organo-sulfur species. We have therefore undertaken the synthesis of these compounds. The starting phenylphosphonic acid diisopropylesters 1 were formed by using a LDA-induced thiophosphate-mercaptophosphonate rearrangement^[2] described earlier and converted into their dimethyl counterpans 2 by means of a trans-silylation procedure followed by alkylation. We have now performed the selective half-hydrolysis of phosphonic acid diesters 1.2 and sulfoxidation of the resulting monoesters.     

Triol Crystalline Hosts Derived from Malic Acid. Synthesis,Inclusion Formation and X-ray Crystal Structures of a Free Host and its Inclusion Compound with Ethanol (1:1)

Abstract

Four new host compounds 1–3 (a, b) derived from malic acid as different optical species and having particular lateral substituents were synthesized. Their properties in crystalline inclusion formation were studied and discussed. Crystal structures of a free host compound 1 and its ethanol inclusion complex [1·EtOH (1:1)] have been determined by X-ray analysis [1: orthorhombic, P2₁2₁2₁, a = 9.304(3), b = 14.950(3), c = 15.712(3) Å, Dc = 1.248 Mg·m^?3, Z = 4, R = 0.039 for 2474 reflexions; 1·EtOH (1:1): triclinic, P 1; a = 11.945(3), b = 14.080(3), c = 16.029(4) Å, α = 106.82(2), β = 97.74(2), γ = 89.93(2)°, D_c = 1.187 Mg·m³, Z = 4, R = 0.096 for 10404 data]. Spontaneous resolution occurs during crystallization in crystals of 1. An interesting H-bonding pattern develops that probably is responsible for the inclusion formation with ethanol in the associate crystal.     

1,2-dihydro-1,2,4,3-triazaphospholo[4,5-a]quinolines as electron carriers in the electrochemical reduction of 1,1-dichloro-2-methoxycarbonyl-2-methylcyclopropane

Electrochemical reduction of 1-X-1-R¹-5-methyl-2-phenyl-7-R²-1,2-dihydro-1,2,4,3-tri-azaphospholo[4,5-a]quinolines1–5 (1: X is the lone electron pair (LEP), R¹=Et₂N, R²=Me;2: X=LEP, R¹=Ph, R²=H;3: X=S, R¹=Et₂N, R²=H;4: X=LEP, R¹=Et₂N, R²=H;5: X=LEP, R¹=MeO, R²=H) in DMF with 0.1M Bu₄NI as supporting electrolyte is reversible and results in metastable radical anions. Radical anions of compounds1–3 efficiently reduce 1,2-dichloro-2-methoxycarbonyl-2-methylcyclopropane both in the presence and in absence of Ni¹¹ ions. Effective reduction rate constants have been evaluated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 1999.     

Synthesis of amidine complexes by metal-mediated addition of amino acid esters to coordinated nitriles

The reaction of the nitrile platinum(IV) complex trans-[PtCl₄(EtCN)₂] with amino acid esters H₂NC(R¹)(R²)CO₂Me (R¹ = R² = H, H-Me, Me-Me, H-Ph) and H₂NCH₂CH₂CO₂Me in CH₂Cl₂ produces the amidine complexes trans-[PtCl₄{ Z-NH=C(Et)NHC(R¹)(R²)CO₂Me}₂] and trans-[PtCl₄{ Z-NH=C(Et)NHCH₂CH₂CO₂Me}₂], which were isolated in 70–80% yields and characterized by elemental analysis, mass spectrometry, IR spectroscopy, and ¹H and ¹³C{¹H} NMR spectroscopy. The structures of the complexes with R¹ = R² = H (1), R¹ = H, R² = Me (2), and R¹ = H, R² = Ph (4) were established by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 601–605, March, 2005.     

Electron impact induced fragmentations of 2-chlorovinyl methyl sulphides

A series of 2-chlorovinyl methyl sulphides, CH₃SCR¹?CR²Cl (R¹, R² = H, Me, Et, t-Bu, Ph; R¹ = H, R² = CH₃) has been analysed under electron impact conditions. The most significant common fragmentations involve primary loss of Cl˙ and methyl radicals. Analysis of the phenyl-substituted derivative suggests that loss of CH₃˙ is a lower activation energy process than loss of Cl˙. The characteristic loss of CH₃SCl from the same derivative has been examined with respect to the structure of the resulting fragment by means of suitable model compounds.