Ph 3P Research Articles

Synthesis of fused pyranocarbazolones with biological interest

Fused pyranocarbazolones were synthesized from the reactions of hydroxycarbazoles with ethyl propiolate in the presence of catalytic amount of I nCl 3. Carbalkoxypyranocarbazolones and methylenefurocarbazolones were obtained from the reactions of hydroxycarbazoles with dialkyl acetylene dicarboxylates in the presence of Ph 3P in refluxing toluene. Furanone 10a (IC 50 = 10 µM) followed by pyranocarbazolones 9a and 11b are interesting lipoxygenase inhibitors. Pyranocarbazolones 9b , 11a-b are potent anti-lipid peroxidation agents and this is correlated to the presence of the coumarin ring.

One-pot synthesis of 2,4,5-trisubstituted oxazoles from N-acyl amino acids by a combination of cyclodehydration with N, N′-diisopropylcarbodiimide and Wittig olefination

By a combination of cyclodehydration of N-acyl amino acids with N, N′-diisopropylcarbodiimide (DIC) and non-classical Wittig olefination of the resultant 5(4 H)-oxazolones with Ph 3P CHCN and Ph 3P CHCOOEt, 5-oxazoleacetonitriles and 5-oxazoleacetates were synthesized in one-pot in 41–85% and 57–70% yields, respectively.

Effects of substituent and catalyst on the intramolecular Povarov reaction—synthesis of chromenonaphthyridines

2-( N-Alkenyl- N-aryl)aminochromone-3-carbaldehyde undergoes intramolecular Povarov reaction with aromatic amines in the presence of Ph 3P·HClO 4 to produce chromenonaphthyridine. The effects of substituent and catalyst have been studied. The substituent on the alkenyl part of aminochromone controls the mode of reaction as well as the stereochemistry of the product.

Synthesis and evaluation of the substrate activity of C-6 substituted purine ribosides with E. coli purine nucleoside phosphorylase: Palladium mediated cross-coupling of organozinc halides with 6-chloropurine nucleosides

A series of C-6 alkyl, cycloalkyl, and aryl-9-(β- d-ribofuranosyl)purines were synthesized and their substrate activities with Escherichia coli purine nucleoside phosphorylase ( E. coli PNP) were evaluated. (Ph 3P) 4Pd-mediated cross-coupling reactions of 6-chloro-9-(2,3,5-tri- O-acetyl-β- d-ribofuranosyl)-purine ( 6) with primary alkyl (Me, Et, n-Pr, n-Bu, isoBu) zinc halides followed by treatment with NH 3/MeOH gave the corresponding 6-alkyl-9-(β- d-ribofuranosyl)purine derivatives 7– 11, respectively, in good yields. Reactions of 6 with cycloalkyl(propyl, butyl, pentyl)zinc halides and aryl (phenyl, 2-thienyl)zinc halides gave under similar conditions the corresponding 6-cyclopropyl, cyclobutyl, cyclopentyl, phenyl, and thienyl -9-(β- d-ribofuranosyl)purine derivatives 12– 16, respectively in high yields. E. coli PNP showed a high tolerance to the steric and hydrophobic environment at the 6-position of the synthesized purine ribonucleosides. Significant cytotoxic activity was observed for 8, 12, 15, and 16. Evaluation of 12 and 16 against human tumor xenografts in mice did not demonstrate any selective antitumor activity. In addition, 6-methyl-9-(β- d-arabinofuranosyl)purine ( 18) was prepared and evaluated.

Lithium chloride-induced organogel transformed from precipitate based on cyclodextrin complexes

This paper describes a novel heat-set organogel transformation which could be triggered by lithium chloride (LiCl) from precipitate for the first time. The system was prepared with β-cyclodextrin (β-CD) and triphenylphosphine (Ph 3P) in N,N-dimethylformamide (DMF). The system as an original transparent solution at room temperature could turn into precipitation by heating. Subsequently, the precipitation turned into organogel instantly based on the injection of LiCl into the system. SEM measurement revealed that the precipitate and gel systems have different microstructures. IR and XRD measurements revealed that the inclusion complexes formed by β-CDs and Ph 3P were arranged in cage structures in the precipitate and channel structures in the gel. Molecular dynamics simulations were performed both on the formation of the precipitate and gel models in this system, which were consistent with the test results.

Synthesis and X-ray structure of an octahedral platinum–silver cluster [(Ph 3P) 2N] 2[Pt 2Ag 4Cl 2(C 2Ph) 8] with disordered silver atoms

Variable-temperature X-ray structural study of the complex [(Ph 3P) 2N] 2[Pt 2Ag 4Cl 2(C 2Ph) 8] prepared by the reaction of cis-[PtCl 2(AsPh 3) 2] and [(Ph 3P) 2N][Ag(C 2Ph) 2] in 1:2 M ratio, revealed isolated (non-polymerised) [Pt 2Ag 4Cl 2(C CPh) 8] 2− anions with a pseudo-octahedral arrangement of metal atoms. The Pt atoms (in mutually trans vertices) are each σ-bonded to four alkynyl ligands in a square planar arrangement; these moieties are bridged by four Ag atoms; each silver atom being η 2-bonded to two alkynyl groups. Chloride ligands are asymmetrically bridging two opposite Ag–Ag edges. Silver atoms show strong and unusual temperature-dependent disorder.

A facile preparation of 2-bromodifluoromethyl benzo-1,3-diazoles and its application in the synthesis of gem-difluoromethylene linked aryl ether compounds

A facile preparation of 2-bromodifluoromethyl benzo-1,3-diazoles as novel CF 2Br-containing heterocyclic building blocks has been developed through a one-pot process of reaction of 2-OH, 2-SH, or 2-NH 2 substituted aniline with bromodifluoroacetic acid in the presence of 3 molar equivalents of CBr 4 and Ph 3P in refluxing toluene. 2-Bromodifluoromethyl benzo-1,3-thiazole ( 2b) was successfully utilized in the preparation of gem-difluoromethylene linked aryl ether compounds through the reaction with phenolates or thiophenolate in DMF in good yields.

Molecular structures and preferred conformations of stabilized keto diester phosphonium ylides

Triphenylphosphonium ylidic keto diesters with a nonylidic ester group, Ph 3P C(CO 2CH 2CH 3)CO CO 2CH 2CH 3, 1, and Ph 3P C(CO 2CH 2CH 3)CO CH 2 CO 2CH 2CH 3, 2, have the keto group syn and the ylidic ester acyl group anti to phosphorus. Conformation of 2 is assigned by X-ray crystallography, while conformations of 1 and 2 are based on 1H and 13C NMR spectroscopy, and comparisons of acyl stretching frequencies with predicted values from HF and DFT methods. Thermolyses of 1 and 2 gave the expected acetylene derivatives in high yield, consistent with the syn keto conformation and in agreement with earlier observations of thermolyses of stabilized phosphonium ylides. Results from the X-ray spectrum of 2 confirm the proposed structure.

Cyclopalladation of thiophene-substituted thiosemicarbazones

The thiosemicarbazones obtained from the condensation of thiosemicarbazide or 4,4′-dimethylthiosemicarbazide with 2-acetylthiophene react with K 2PdCl 4 in the presence of a base to give dark, poorly soluble materials in high yields. Treatment of these oligomeric compounds with Ph 3P, dppe or dppf gives monomeric palladium(II) phosphine complexes in which the deprotonated thiosemicarbazones coordinate to the metal in a tridentate fashion through the C3-cyclometallated thiophene ring, the imine nitrogen atom and the sulphur atom. This coordination mode was confirmed by X-ray structure analysis of several derivatives.

Synthesis of 4,4-dialkoxy-3-piperidinols. Application to the synthesis of γ-acetate dehydropipecolinonitrile

The synthesis of 4,4-dialkoxy-3-piperidinols 7 was carried out by the α-bromination of piperidin-4-one 5 with N-bromosuccinimide in acetic acid and alkoxide ion-mediated α,α-dialkoxyhydroxylation. Under acidic condition, trimethyl orthoformate-mediated reaction of compound 7a yielded aminodienylester 8 in the presence of Ph 3P CHCO 2Et. The γ-acetate dehydropipecolinonitrile 4 was also synthesized via boron trifluoride etherate-promoted addition of compound 8 with trimethylsilyl cyanide and N-bromosuccinimide and selective hydrogenation.

Synthesis of tetrahydrobenzoisoquinolinols, tetrahydropyrindines, and hexahydroquinolines from 4-aryltetrahydropyridines

A straightforward synthesis of tetrahydrobenzoisoquinolinols 2, tetrahydropyrindines 3, and hexahydroquinolines 4 from versatile intermediate 6 is reported. Two key transformations were carried out by intramolecular Friedel–Crafts cyclization and ring-closing metathesis in moderate yields. Skeleton 6 was easily prepared from the known starting material 4-aryl-4-methoxypiperidin-3-ones 7 via Wittig olefination with Ph 3P=CHCO 2Et, deconjugation with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and boron trifluoride etherate (BF 3–OEt 2)-catalyzed addition of the corresponding iminium ion with allyltrimethylsilane.

Synthesis, characterization and antimicrobial studies of mixed ligand silver(I) complexes of triphenylphosphine and heterocyclic thiones: Crystal structure of bis[{(μ 2-diazinane-2-thione)(diazinane-2-thione)(triphenylphosphine)silver(I) nitrate}

Mixed ligand silver(I) complexes of triphenylphosphine and heterocyclic thiones (imidazolidine-2-thione (Imt), diazinane-2-thione (Diaz) and 2-mercaptopyridine (Mpy)) having the general formulae [(Ph 3P)Ag(thione) 2]NO 3 and [(Ph 3P) 2Ag(thione)]NO 3 were prepared and characterized by elemental analysis, IR and NMR ( 1H, 13C and 31P) spectroscopic methods. The crystal structure of one of the complexes, [Ag(Ph 3P)(Diaz) 2] 2(NO 3) 2 ( 1) was determined by X-ray crystallography. The title complex ( 1) is dinuclear, having each silver atom coordinated to three thione sulfur atoms of Diaz and to one phosphorus atom of PPh 3 in a nearly tetrahedral environment, with an average P–Ag–S bond angle of 108.5°. The spectral data of the complexes are consistent with sulfur coordination of the thiones to silver(I). Antimicrobial activities of the complexes were evaluated by minimum inhibitory concentrations and the results showed that the complexes exhibit a wide range of activity against two gram-negative bacteria ( E. coli, P. aeruginosa) and molds ( A. niger, P. citrinum), while the activities were poor against yeasts ( C. albicans, S. cerevisiae).

Green luminescence from triphenylphosphine functionalized single-wall carbon nanotubes

In a simple wet chemical process, purified single-wall carbon nanotubes (SWCNTs) are treated with triphenylphosphine (Ph 3P) at room temperature. The functionalized material is characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. HRTEM micrograph clearly reveals that triphenylphosphine nanocrystals of nearly uniform size are attached to the surfaces of SWCNTs. The hybrid structure shows remarkable green luminescence with peak emission at around 500 nm, under UV excitation. The photoluminescence may be attributed to charge transfer from the electron-donating phosphorous atoms to the carbon nanotubes.

In situ benzene-1,4-disulfonate ligand synthesis and electric conductivities of four silver 4-sulfobenzoate or benzene-1,4-disulfonate complexes

The reaction of 4,4′-bipyridine (bipy), AgNO 3 and 4-sulfobenzoate (4-sb) led to an unprecedented complex, {[Ag 2(4,4′-bipy) 2(H 2O) 2]·(1,4-bds)·(2H 2O)} n ( 1), in which benzene-1,4-disulfonate (1,4-bds) was synthesized in situ. This does not happen in the similar 1,2-bis(4-pyridyl)ethylene (bpe) system, where the complex {[Ag 2(bpe) 2(H 2O) 2]·(4-sb)·3H 2O} n ( 2) is formed. The same in situ reaction occurred when triphenylphosphine (PPh 3) was added into the bipy and silver reaction solution, resulting in the complex [Ag 2(PPh3) 4(1,4-bds)]. 2DMF ( 3). Complex 4, {[Ag 2(Ph 3P) 2(4-sb)(H 2O)]·(H 2O)} n , was synthesized similar to the synthesis of complex 3, without the presence of 4,4′-bipyridine. Complexes 1– 4 were characterized by single-crystal X-ray analyses, elemental analyses, IR spectra, TG analyses, fluorescence studies and electric conductivity. Complexes 1 and 2 are cation–anion species. Complexes 3 and 4 are silver triphenylphosphine complexes, where the phenyl embrace interactions play important roles. In 3, the six-fold phenyl embrace (6PEs) connect the molecules into a 1- d hybrid zig-zag infinite chain. Complex 4 is a one-dimensional branch-like polymer containing a 1- d necklace-like backbone made up of an [Ag 2(4-sb)(H 2O)] unit and PPh 3 ‘‘leaves”. Two new coordination modes for the 1,4-bds ligands and one for the 4-sb ligand are observed. Complexes 1– 3 are semi-conductors, while complex 4 is an insulator.

Wittig reaction with ion-supported Ph 3P

Ion-supported Ph 3P, 4-(diphenylphosphino)benzyltrimethylammonium bromide A and N-methyl- N-[4-(diphenylphosphino)benzyl]pyrrolidinium bromide B, were used for the Wittig reaction. Ion-supported phosphonium salts A1 and B1, which were prepared from the reactions of ion-supported Ph 3P A and B with ethyl bromoacetate, respectively, reacted with aromatic and aliphatic aldehydes in the presence of K 2CO 3 to give the corresponding α,β-unsaturated ethyl esters in good yields with high purity by simple filtration of the reaction mixture and subsequent removal of the solvent from the filtrate. Similarly, ion-supported phosphonium salts A2 and B2, which were prepared from the reactions of ion-supported Ph 3P A and B with p-methylbenzyl bromide, respectively, reacted with aromatic and aliphatic aldehydes in the presence of NaH to provide the corresponding p-methylstyrene derivatives in good yields with high purity by simple filtration of the reaction mixture and the subsequent removal of the solvent from the filtrate. In both reactions, the co-product, ion-supported Ph 3PO, could be obtained quantitatively by simple filtration, and was converted into the corresponding ion-supported Ph 3P A and B again in high yields using dimethyl sulfate, followed by the reduction with LiAlH 4. Recovered and regenerated ion-supported Ph 3P A and B could be reused for the same Wittig reaction while maintaining good yields of ethyl ( E)-3-(4′-chlorophenyl)-2-propenoate and 1-(4′-chlorophenyl)-2-(4″-methylphenyl)ethene with high purity by simple filtration and removal of the solvent from the filtrate.

Cross-coupling reactions of gold(I) alkynyl and polyyndiyl complexes

Gold(I) alkynyl complexes are shown to efficiently couple with aryl iodides under mild conditions in the presence of both Pd(II) and Cu(I) co-catalysts. The reaction is not gold catalysed, but rather the Au(I) centre serves to transfer the alkynyl moiety to Cu(I), which then enters the conventional Sonogashira cycles. Using this method, a small range of 1,4-disubstituted diynes, including examples of differentially substituted compounds ArC CC CAr′, have been prepared directly from [(Ph 3P)AuC CC CAu(PPh 3)] and aryl iodides ArI.

Reactivity and regioselectivity in Stille couplings of 3-substituted 2,4-dichloropyridines

The influence of substituents at C-3 of 2,4-dichloropyridines on their reactivity and regioselectivity in Pd-catalyzed cross-couplings is studied. As a model reaction, the (Ph 3P) 2PdCl 2-catalyzed Stille coupling between 2-furyl(tributyl)tin and pyridines is chosen. Increased electron-withdrawing ability of a substituent at the pyridine 3-position improves the overall reactivity. Absolute selectivity for coupling at C-2 is achieved with an amino group at C-3, and the selectivity is totally reversed when the amino group is exchanged for a nitro substituent.

Synthesis of О-2-(acyl)vinylketoximes and their unusual rearrangements into 2- and 3-acyl-substituted pyrroles

О-2-(Acyl)vinylketoximes (freshly prepared from ketoximes and acylacetylenes in the presence of Ph 3P as catalyst in up to 83% yields) rearrange upon heating (125–150 °C) to give 2- or 3-acylpyrroles, wherein the positions of the acyl substituents do not correspond to known O-vinyloxime rearrangements; the chemo- and regioselectivity of the rearrangements depend on the reaction conditions. The described rearrangement enables syntheses of previously inaccessible substituted 2- or 3-acylpyrroles.

Thermogravimetrical investigations of the dealkoxycarbonylation of N-acyl-α-triphenylphosphonioglycinates

Thermogravimetrical experiments revealed that immediately after the endothermic process of the melting of N-acyl-α-triphenylphosphonioglycinates 1, an exothermic demethoxycarbonylation of phosphonioglycinates commenced, accompanied by the release of CO 2. The residues contained the corresponding N-acylaminomethyltriphenylphosphonium salts 2 (18.3–49.5%), methyltriphenylphosphonium salts 7 (21.8–67.9%), and the corresponding 1,2-di( N-acylamino)fumaric acid dimethyl ester 6 (2.1–26.0%). When the reaction was carried out in the presence of Ph 3P and the corresponding triphenylphosphine hydrobromide, hydroiodide, or tetrafluoroborate, N-acyl-α-triphenylphosphoniumglycinate bromides and iodides 1a– f underwent demethoxycarbonylation to form the corresponding N-acylaminomethyltriphenylphosphonium salts 2a– f at 95–130 °C in good to excellent yields (79–100%). On the other hand, tetrafluoroborates 1g– i underwent corresponding reactions at about 170–175 °C to give phosphonium tetrafluoroborates 2g– i in much lower yields (34–67%). Plausible mechanisms of the investigated reaction are discussed. It was also demonstrated that the obtained crude α-( N-acylamino)alkyltriphenylphosphonium salts 2 could be applied as valuable α-amidoalkylating agents in spite of their contamination with inert methyltriphenylphosphonium salts 7.

Halo-complexes of titanium(III): The thermochromic behaviour of [NBu 4][TiCl 4(THF) 2

TiCl 3(thf) 3 reacts with ACl (A = NBu 4, PPN; PPN = Ph 3P N PPh 3) in dichloromethane solution, affording the compounds A[TiCl 4(thf) 2] (A = NBu 4, 1; A = PPN, 2). Compound 1, dissolved in CH 2Cl 2, exhibits thermochromic behaviour which has been the subject of variable-temperature UV–Vis investigations.