REACTION OF SCHIFF BASE OF THIOHYDRAZIDES WITH P(NR2)3

Abstract

Three pathways were observed in the reactions of Schiff bases of Thiohydrazides with P(NR₂)₃. (a) MeS-R₂N exchange: MeS-C([dbnd]S)-NHN[dbnd]CHPh (1) reacted with P(NR₂)₃ led to new Schiff bases, R₂N-C([dbnd]S)-NHN[dbnd]CH = Ph (2). (b) Cleavage of C[dbnd]S bond and the formation of P[dbnd]S bond: H₂N-C([dbnd]S)-NHN[dbnd]CH = Ph (3) reacted with P(NR₂)₃ gave rise to the thiophosphoric amide. (Et₂N)₂P([dbnd]S)-NH-CH = N-N[dbnd]CH-Ph (4). (c) Formation of thiadiazole and triazole: Schiff bases 2a and H₂N(MeS)C = N-N[dbnd]CH-Ph (6) reacted with P(NR₂)₃ respectively and produced 5-dimethylamino-2-phenyl-2,3-(2H)-1,3,4-thiadiazole (5) and 5-methylthio-2-phenyl-2,3-(2H)-1,3,4-triazole (7).     

Quinoline-pyrimidine hybrid compounds from 3-acetyl-4-hydroxy-1-methylquinolin-2(1H)-one: Study on synthesis,cytotoxicity, ADMET and molecular docking

Some novel 2-amino-6-aryl-4-(4′-hydroxy-N-methylquinolin-2′-on-3′-yl)pyrimidines have been synthesized from α,β-unsaturated ketones of 3-acetyl-4-hydroxy-N-methylquinolin-2-one by reaction of corresponding α,β-unsaturated ketones with guanidine hydrochloride. The purity and structure of the obtained products have been confirmed by thin layer chromatography, IR, ¹H NMR, ¹³C NMR, HSQC, HMBC and MS spectra. All the synthesized of 3-(2-amino-6-arylpyrimidin-4-yl)-4-hydroxy-1-methylquinolin-2(1H)-ones 6a-i were screened for their in vitro cytotoxic activity against human hepatocellular carcinoma HepG2 and squamous cell carcinoma KB cancer lines. Compounds 6b and 6e had the best activity in the series, with IC₅₀ values equal to 1.33 μM. Compounds 6a-g exhibited weak or insignificant activity with liver cancer cell lines HepG2, while compounds 6a and 6g had more powerful activity in this sequence, with IC₅₀ values equal to 47.99 and 89.38 μM, respectively. ADMET properties showed that compounds 6b, 6e, and 6f possessed the drug-likeness behavior. Cross-docking results indicated that two hydrogen bonding interactions in the binding pocket, as potential ligand binding hot-spot residues for compounds 6b and 6e, may be one of the mechanisms of action responsible for the higher cytotoxic effect on HepG2 and KB cells.     

Reactions of polyfluoroaromatic compounds with electrophilic agents in the presence of tris(dialkylamino)phosphines

When reacted with P(NEt₂)₃ and a proton donor, pentafluoropyridine, 3-chlorotetrafluoropyridine, pentafluorobenzonitrile, and octafluorotoluene yield products of replacement of the fluorine atom by hydrogen at position 4. This process is accompanied by the side reaction of aminodefluorination. In the case of 3-H-heptafluorotoluene and octafluoronaphthalene, aminodefluorination is the main reaction. Reactions of perfluoro-4-isopropyltoluene, 4-H-heptafluorotoluene, and 4-methylheptafluorotoluene do not occur under the above-mentioned conditions. For Part 7, see Ref. I. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1498–1500, August, 1997.     

Synthetic application of fluorinated vinamidinium salts: Synthesis of fluorinated 1,3-butadienylphosphonates by the reaction with Horner-Wadsworth-Emmons reagents

The reaction of β-fluoro vinamidinium salt 1 with Horner-Wadsworth-Emmons reagents (HWE) such as diethyl(ethoxycarbonyl)methylphosphonate (2a), diethyl(methoxycarbonyl)methylphosphonate (2b), diethyl-2-oxopropylphosphonate (2c), diethyl benzylphosphonate (2d), tetraethyl methylenediphosphonate (2e) and diethyl cyanomethylphosphonate (2f) under basic conditions gave the fluorinated 1,3-butadienylphosphonates 3 in moderate to good yields. The phosphonates 3 could be hydrolyzed with a 10% HCl aqueous solution to afford the corresponding γ-(diethylphosphono)-α-fluoro-α,β-unsaturated aldehydes 7 in good yields. The treatment of the phosphonate 3c with an NH₃ aqueous solution at 70 °C produced the pyridine derivative 8 in 60% yield.     

Atom-Economic Synthesis of Tris[2-(organylthio)ethyl]phosphine Oxides from Phosphine and Vinyl Sulfides

Abstract

Phosphine, generated from elemental phosphorus in the system KOH-toluene-H₂O, reacts with vinyl sulfides under free radical conditions (AIBN, dioxane, 65–70°C, atmospheric pressure) to form regiospecifically tris[2-(organylthio)ethyl]phosphines, which are readily oxidized in air to corresponding tris[2-(organylthio)ethyl]phosphine oxides.     

Molecular structure of (3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine oxide. Synthesis of (3,5-diallylisocyanuratomethyl)phosphine sulfides

X-Ray study of the (3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine oxide showed that the phosphorylmethyl group is bonded to the nitrogen atom of the cycle. Reaction of the tris(chloromethyl)phosphine sulfide with sodium diallylisocyanurate gave (3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine sulfide, and treatment of the tris(3,5-diallylisocyanuratomethyl)phosphine oxide with phosphorus pentasulfide gave a tris(3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine sulfide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1446–1448, August, 1993.     

Chemoselective hydrogenation of α,β-unsaturated aldehydes with modified Pd/C catalyst

Selective hydrogenation of α, β-unsaturated aldehydes with modified Pd/C catalyst was developed.The reduction of C=O bond could be efficiently inhibited by the addition of carbonates,and high selectivity to the corresponding saturated aldehydes was achieved under mild conditions.This protocol provides an alternative for efficient preparation of saturated aldehydes.     

Ambidentate coordination of the tripyridyl ligands 2,2′:6′,2″-terpyridyl,tris(2-pyridyl)-amine,tris(2-pyridyl)methane and tris(2-pyridyl)phosphine to carbonylrhenium centres: Structural and spectroscopic studies

The reactions of [Re(CO)₅Cl] with the ligands tpy (2,2′:6′,2″-terpyridine), py₃N {tris(2-pyridyl)-amine}, py₃CH {tris(2-pyridyl)methane}, and py₃P {tris(2-pyridyl)phosphine} in toluene solution realize compounds with the general formulation [Re(ligand)(CO)₃Cl] in which the tripyridyl ligands are bidentate. X-ray structural determinations of fac-[Re(typ)(CO)₃Cl].H₂O and fac-[Re(py₃N)(CO)₃Cl] confirm these assignments. [Re(tpy)(CO)₃Cl].H₂O (C₁₈H₁₃ClN₃O₄Re) is monoclinic, space group P2₁/n, with cell dimensions a = 7.432(2) Å, b = 17.016(4) Å, c = 14.466(2) Å, β = 93.51(2)°, and Z = 4; full-matrix least-squares refinement on 2435 reflections with I ? 2.5σ(I) converged to a final R = 0.028 and R_w = 0.029. [Re(py₃N)(CO)₃Cl] (C₁₈H₁₂ClN₄O₃Re) is triclinic, space group P1 with cell dimensions a = 13.761(2) Å, b = 14.636(6)Å, c = 11.110(2) Å, α = 110.70(2)°, β = 102.45(2)°, γ = 107.48(2)°, and Z = 4; full-matrix least-squares refinement on 3459 reflections with I ? 2.5σ(I) converged to a final R = 0.038 and R_w = 0.039. If the synthetic procedure is undertaken under irradiation by visible light, for the ligand py₃N a species [Re(py₃N)(CO)₂Cl] (characterized by infrared spectroscopy and conductance measurements) is also formed, in which the ligand py₃N is tridentate. No analogous tridentate species is formed with the ligands tpy or py₃P, although there is evidence that it also forms for py₃CH.     

The Reactions of 1-Acetothiosemicarbazidc with P(NR_2)_3 PC1_3 and PCI_5

A Series of new heterocyciophosphorus compounds were synthesizec oy cyclocondensa-tion of 1-acetothiosemicarbazide with P(NR2)3. The further reaction of these compounds with P(NR2)3 gave different compounds depending upon different reaction conditions. The 1-acetothiosemicarbazide can also condense with PCl3 and PCl5 similarly, The reaction mechanism, the spectral properties and chemical properties of these products were also studied and discussed.     

Thermal rearrangement of bis(hydroxymethyl)phosphines as a way to P-chiral phosphine oxides

Bis(hydroxymethyl)(2-pyridyl)- and bis(hydroxymethyl)-[(2-pyridyl)ethyl]phosphines on heating to 180 °C undergorearrangement leading to racemic P-chiral tertiary P-methyl-P-(hydroxymethyl)-containing phosphine oxides. The spontaneous self-resolution of these enantiomer mixtures during the crystallization was demonstrated.     

The Electronic Nature of the P=C Bond

Abstract

The influence of substituents at the carbon of the P=C bond of about 60 phosphaalkenes was investigated by ³¹P NMR spectroscopy. The P=C system is characterized as electronwithdrawing. All compounds were found to be configurationally stable.     

Convenient syntheses of (3S,5S)-carbapenam-3-carboxylates and their biosynthetic relevance

Starting from readily available glutamate derivatives, facile stereoselective syntheses of (3S,5S)-carbapenam-3-carboxylates have been developed. Their significance in confirming the absolute configuration of the natural material is discussed.     

Reactions of polyfluoroaromatic compounds with electrophilic agents in the presence of tris(dialkylamino)phosphine

The rate of replacement of the halogen atom in isomers of RC₆F₄X (X=Cl, Br, or I) by the SiMe₃ group under the action of Me₃SiCl and P(NEt₂)₃ depends on the nature and the mutural arrangement of the substituents X and R. In addition to silyldehalogenation, compounds C₆HF₄X (X=Br or I) undergo silyldeprotonation and reduction to tetrafluorobenzenes. For Part 5, see Ref. 1 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 813–818, April, 1997.     

Reactions of 4-ethoxy-l,l,l-trifluoro-3-buten-2-one with phosphorous nucleophiles: Diethyl phosphite, tributyl phosphine and tris(diethylamino) phosphine

The reaction of (E)-4-ethoxy-l,l,l-trifluoro-3-buten-2-one EtOCHCHCOCF₃1 with diethyl phosphite (EtO)₂P(O)H 2 afforded a 1:1 cis- and trans-mixture of diethyl(l-trifluomethyl-3-ethoxy)allyl-phosphate EtO-CHCH-CH(CF₃)OP(O)(OEt)₂3 via the 1,2-λ⁵-oxaphosphol-4-ene intermediate. While tributyl phosphine Bu₃P added to 1 giving the double addition product Bu₃P⁺CH₂-C⁻(COCF₃)-CHCH-COCF₃5. Its resonance structure was fully identified by spectral methods and single crystal X-ray diffraction analysis. More strong phosphorous nucleophile tris(diethylamino) phosphine (Et₂N)₃P reacted with 1 to give the known compound (E)-4-(diethylamino)-l,l,l-trifluoro-3-buten-2-one Et₂N-CHCH-COCF₃10 in good yield.     

A general route to α-alkyl (E)-α,β-unsaturated aldehydes

Bis(trimethylsilyl)-tert-butylaldimines 3 react with aldehydes in the presence of zinc bromide at room temperature to give, after hydrolysis, the desired α-alkyl α,β-ethylenic aldehydes in good yield and with very high E stereoselectivity. The reaction was believed to proceed via the α-silyl β-siloxyimines 4.     

Tris(4-anisyl)phosphine as an Efficient and Practical Reagent for the Synthesis of (E)-2-Benzylidenesuccinates

Condensation of maleic anhydride or dimethyl maleate with benzylaldehydes controlled by tris(4‐anisyl)‐phosphine to synthesize dimethyl (E)‐2‐benzylidenesuccinates has been systematically investigated. The protocol gives the product with high stereoselectivity in moderate to good yields under mild conditions. A plausible mechanism has been proposed.     

Interaction of tetracyanoethylene with α,β-unsaturated aldehydes. Synthesis of 2,4-dialkyl-7-imino-6-oxabicyclo[3.2.1]oct-3-ene-1,8,8-tricarbonitriles

The reaction of tetracyanoethylene with α,β-unsaturated aldehydes under hydrochloric acid catalysis leads to 2,4-dialkyl-7-imino-6-oxabicyclo[3.2.1]oct-3-ene-1,8,8-tricarbonitriles. The structures of these new cyclohexene derivatives were determined by NMR experiments and X-ray crystallography.     

Conductance of tris(hydroxymethyl)-aminomethane hydrochloride (Tris·HCl) in water at 25 and 37°C

The conductances of aqueous solutions of tris(hydroxymethyl)aminomethane hydrochloride (Tris·HCl) at 25°C and 37°C have been measured. The concentration of salt varied from 4×10^–4 to 1.6×10^–2 mole-dm^–3. The data were analyzed by the full Pitts equation which yielded the following parameters: at 25°C, ° = 106.07 S-cm²-mole^–1, K_A=1.01; at 37°C, ° = 106.07 S-cm²-mole^–1, K_A=0.99. These values suggest that Tris·HCl is essentially completely dissociated in water. The mobility of the Tris·H⁺ ion was found to be considerably smaller than that of the alkali metal cations. This result is consistent with abnormal liquid-junction potentials for Tris buffer solutions at 25 and 37°C.     

Dimethylaluminum methide complex Tf2CHAlMe2: an effective catalyst for Diels-Alder reaction of α,β-unsaturated lactone derivatives with cyclopentadiene

Lewis acid derived by mixing Tf₂CH₂ and Me₃Al was found to be an effective catalyst system for the catalytic DA reaction of less reactive α,β-unsaturated lactone derivative with cyclopentadiene (CP). In this catalyst system, Tf₂CHAlMe₂ is an active species and an excess amount of Me₃Al plays an important role to lower the catalyst loading. Substituent effect of the lactone framework on π-facial selectivity was also examined. In the reactions of both γ-substituted 5-membered lactone derivatives and γ- or δ-methylated 6-membered lactone derivatives with CP, selective attack on the anti face of γ- or δ-substituent was observed. On the other hand, in the cases of γ- or ?-methylated 7-membered lactone derivatives, CP favorably attacked on the syn face.