Synthesis of 2- and 4-chloropyrimidines with hydroxyphenyl substituents by the interaction of Vilsmeier-Haack reagents with (hydroxyphenyl)dihydropyrimidin-2- and -4-ones

The reaction of 2- and 4-hydroxypyrimidines containingortho- andpara-hydroxyphenyl substituents with Vilsmeier-Haack reagents generatedin situ from DMF and SOCl₂ or POCl₃ results in the chemoselective replacement of the heterocyclic hydroxyl group by chlorine and formylation of the phenolic hydroxyl group. Aryl formates are hydrolyzed under the conditions of their isolation to give the corresponding phenols, especially if the pyrimidyl fragment isortho to the formyloxy group.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1105–1108, June, 1993.     

Die vollständige Methylierung phenolischer Hydroxylgruppen in Mehrkernverbindungen mit aromatisch gebundenem Chlor

Zusammenfassung Ein bei der Permethylierung von Kohlenhydraten bewährtes Verfahren [Methylierung mit Dimethylsulfat/Ba(OH)₂ inDMF/DMSO]¹ konnte auf phenolische Mehrkernverbindungen übertragen werden. Das Verfahren hat den Vorteil, unter den Reaktionsbedingungen aromatisch gebundenes Chlor unberührt zu lassen.

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Permethylation of phenolic hydroxyl groups in polycyclic chlorophenols

Methylation with dimethyl sulfate/Ba(OH)₂ inDMF/DMSO ¹ a well-established permethylation procedure in carbohydrate chemistry, has successfully been applied to permethylation of phenolic hydroxyl groups in polycyclic chlorophenols. Under the conditions of the reaction, the chlorine atoms are not attacked.

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Der Nachweis der Kettenstruktur von aus p-Kresol und Formaldehyd aufgebauten Mehrkernverbindungen, VI. Mitt.     

Synthesis of 1-vinylpyrrole-2-carbonitriles

A new highly synthetically potent series of bifunctional pyrroles, 1-vinylpyrrole-2-carbonitriles, were synthesized from readily available 1-vinylpyrrole-2-carbaldehyde oximes by two methods: (1) reaction with acetylene (KOH/DMSO, 70 °C, 10 min, yields 58-67%) and (2) reaction with acetic anhydride (90-100 °C, 5 h, yields 83-93%). Starting from 2-phenyl-1-vinylpyrrole, the one-pot synthesis of the corresponding 1-vinyl-2-carbonitrile was accomplished directly by successive treatment with a DMF/(COCl)₂ complex, NH₂OH·HCl/NaOAc, and acetic anhydride (yield 58%).     

Expedient and High-Yield Synthesis of Alkylphos-Phonyl Bichlorides Under Mild,Neutral Conditions: Reaction of Bis(Trimethylsilyl)Alkyl Phosphonates with Oxalyl Chloride/Dimethylformamide

Structurally variant bis(trimethylsilyl)alkyl phosphonates were converted in high yields (80–88%, distilled) to the corresponding phosphonyl dichlor-ides upon reaction with (COCl)₂/DMF.     

Preparation of Polymer-Supported Chiral 1,2-Diamine as an Efficient Ligand for Asymmetric Hydrogenation Catalyst

An enantiopure 1,2-diamine having two phenolic hydroxy groups was synthesized, and attached to chloromethylated poly(styrene) through a benzyl ether linkage. The polymer-supported Ru precatalysts were prepared from the polymeric chiral 1,2-diamine and RuCl₂/BINAP complex. In the presence of t-BuOK the polymeric catalyst system worked well in asymmetric hydrogenation of aromatic ketones in a mixed solvent of 2-propanol and DMF. The insoluble polymeric catalyst was readily separated from the reaction mixture and reused at least several times without loss of the catalytic activity.     

2‐Chloro‐3‐(dimethylamino)prop‐2‐enoyl Fluoride,a Stable Acyl Fluoride

The title compound is formed as a side‐product in the reaction of CF₃CCl₃ with Zn/DMF and dimethyl(thexyl)silyl chloride (=dimethyl(1,1,2‐trimethylpropyl)silyl chloride). The structure and the double‐bond configuration are deduced from its ¹³C‐NMR data. Its formation is discussed in terms of a Vilsmeier‐type formylation and a reductive elimination.     

Synthesis of aromatic polyethersulfone‐based graft copolyacrylates via ATRP catalyzed by FeCl2/isophthalic acid

The atom transfer radical polymerization (ATRP) catalyzed by the FeCl₂/isophthalic acid system was used for the preparation of novel aromatic polyethersulfone (PSF)‐based graft copolymers in N,N‐dimethylformamide (DMF), such as aromatic PSF‐graft‐poly(methyl methacrylate), aromatic PSF‐graft‐polymethylacrylate, and aromatic PSF‐graft‐poly(butyl acrylate). The route consisted of two steps. The first step included the chloromethylation of aromatic PSF, and the second step involved the ATRP of acrylate monomers using chloromethylated aromatic PSF as the macroinitiator and FeCl₂/isophthalic acid as the catalyst in DMF. Characterization data by gel permeation chromatography, DSC, IR, ¹H NMR, and thermogravimetric analysis confirmed that the graft copolymerization was successful. Only one glass‐transition temperature (T_g) was observed for aromatic PSF‐graft‐poly(methyl methacrylate), and two T_g's were detected for aromatic PSF‐graft‐methyl acrylate and aromatic PSF‐graft‐poly(butyl acrylate). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2943–2950, 2001     

Structural Variability and Gas Adsorption Properties of Coordination Polymers Constructed with Aromatic Multicarboxylic and Bidentate Ligands

The self‐assembly reactions of transition metal ions and 1,3,5‐benzenetricarboxylic acid (H₃btc) in the presence of auxiliary aromatic bidentate ligands 1,10‐phenanthroline (1,10‐phen) or 4,4′‐bipyridine‐N,N′‐dioxide (4,4′‐bpdo) have isolated four coordination polymers [Co₁₈(btc)₁₀(H₂O)₆(OH)₆(1,10‐phen)₆] · 14H₂O · 3DMF ( 1 ) and [M₃(btc)₂(H₂O)₄(4,4′‐bpdo)] · 2H₂O · 2DMF [M = Co ( 2 ), Mn ( 3 ), Ni ( 4 )]. Single‐crystal X‐ray diffraction analysis revealed that the M₃ clusters in the structure of 1 – 4 are connected by hydroxyl group oxygen atoms (or oxygen atoms from 4,4′‐bpdo ligands) and carboxyl groups to generate a three‐dimensional framework. The network of final assemblies can be adjusted by varying the type of auxiliary ligands (1,10‐phen, 4,4′‐bpdo). In addition, the gas adsorption properties of 2 are also investigated.     

Zinc Powder Catalysed Formylation and Urealation of Amines Using CO2 as a C1 Building Block†

Transformation of CO₂ into valuable organic compounds catalysed by cheap and biocompatible metal catalysts is one of important topics of current organic synthesis and catalysis. Herein, we report the zinc powder catalysed formylation and urealation of amines with CO₂ and (EtO)₃SiH under solvent free condition. Using 2 mol% zinc powder as the catalyst, a series of secondary amines, both the aromatic ones and the aliphatic ones, can be formylated into formamides. When primary aromatic amines were used as the substrates, the reactions produce urea derivatives. The electronic and steric effects from the substrates on the formylation and urealation reactions were observed and discussed. The recovery and reusability of zinc powder were investigated, showing the zinc powder can be reused in the formylation reaction without loss of catalytic activity. The analysis on the reactants/products mixture after filtering out the zinc powder showed the zinc concentration in the mixture is low to 1 ppm. The pathways for the formylation and urealation of amines with this catalytic system were also investigated, and related to the different substrates.     

Fragmentation characteristics of hydroxycinnamic acids in ESI‐MSn by density functional theory

This work aims to analyze the electrospray ionization multistage mass spectrometry (ESI‐MSⁿ) fragmentation characteristics of hydroxycinnamic acids (HCAs) in negative ion mode. The geometric parameters, energies, natural bond orbitals and frontier orbitals of fragments were calculated by density functional theory (DFT) to investigate mass spectral fragmentation mechanisms. The results showed that proton transfer always occurred during fragmentation of HCAs; their quasi‐molecular ions ([M − H]⁻) existed in more than one form and were mainly with the lowest energy. The fragmentation characteristics included the followings: (1) according to the different substitution position of phenolic hydroxyl group, the ring contraction reaction by CO elimination from benzene was in an increasingly difficult order: m‐phenolic hydroxyl > p‐phenolic hydroxyl > o‐phenolic hydroxyl; and (2) ortho effect always occurred in o‐dihydroxycinnamic acids (o‐diHCAs), i.e. one phenolic hydroxyl group offered H⁺, which combined with the other one to lose H₂O. In addition, there was a nucleophilic reaction during ring contraction in diHCAs that oxygen atom attacked the carbon atom binding with the other phenolic hydroxyl to lose CO₂. The fragmentation characteristics and mechanism of HCAs could be used for analysis and identification of such compounds quickly and effectively, and as reference for structural analogues by ESI‐MS. Copyright © 2017 John Wiley & Sons, Ltd.     

Synthesis and characterization of phenolic hydroxyl terminated phenylquinoxaline oligomers

The synthesis of phenylquinoxaline oligomers of predictable molecular weight and with phenolic hydroxyl functional end groups is reported. The synthetic procedure utilizes 4-hydroxybenzil as a substituted monofunctional monomer in a conventional PPQ synthesis to both control molecular weight and introduce the functional end groups. The molecular weights of the oligomers were determined by derivatization of the hydroxyl end groups with 3-(trimethylsilyl)propionyl chloride, followed by ¹H-NMR analysis. Comparison of the integration of the trimethylsilyl resonance to the aromatic resonances allowed calculation of the number average molecular weight. A plot of log(η) vs. log(M_n) correlated well with that reported for high molecular weight PPQ. The end groups influenced the solubility behavior of the oligomers in chlorinated solvents, possibly due to hydrogen bonding. The oligomers were chain-extendable to high molecular weight, confirming their suitability for utilization in copolymerizations to prepare phenylquinoxaline-based block copolymers.     

6‐Polyfluoroacyl‐ and 6‐trichloroacetylnorkhellins: Synthesis and reaction with aromatic amines

Five new 6‐polyhaloacylnorkhellins were synthesized in high yields from diethoxymethyl acetate and the condensation products of khellinone with R_FCO₂Et and CCl₃COCl. Reaction of 6‐polyfluoroacylnorkhellins with primary aromatic amines yielded 6‐(arylaminomethylene)‐7‐hydroxy‐4,9‐dimethoxy‐7‐(polyfluoroalkyl)furo[3,2‐g]chroman‐5‐ones. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:99–103, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20174     

Direct polycondensation of aromatic dicarboxylic acids and bisphenols with tosyl chloride and N,N-dimethylformamide in pyridine

A Vilsmeier adduct derived from arylsulfonyl chlorides and DMF in pyridine was successfully used as a new condensating agent for the synthesis of aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols and also of hydroxybenzoic acids. Polymers of high molecular weights (M?_w = 78,000) with relatively narrow molecular weight distribution (M?_w/M?_n ≈ 3.0) were prepared by reacting aromatic dicarboxylic acids with the adduct in pyridine, followed by addition of bisphenols. The polycondensation was significantly affected by the amount of DMF, the nature of the arylsulfonyl chlorides, the conditions of initial reaction of the acids with the adduct, and the rate of reaction with bisphenols. The process was adaptable to the direct polycondensation of hydroxybenzoic acids, affording polymers of high molecular weight (η_inh = 1.73).     

Chelating Phosphorus–An O,C, O-Coordinating Pincer-Type Ligand Coordinating PIII and PV Centres

The sequence of reactions of the phosphorus-containing aryllithium compound 5-t-Bu-1,3-[(P(O)(O-i-Pr)₂]₂C₆H₂Li (ArLi) with Ph₂PCl, KMnO₄, elemental sulfur and elemental selenium, respectively, gave the aryldiphenylphosphane chalcogenides 5-t-Bu-1,3-[(P(O)(O-i-Pr)₂]₂C₆H₂P(E)Ph₂ ( 1 , E=O; 2 , E=S; 3 , E=Se). Compound 1 partially hydrolysed giving [5-t-Bu-1-{(P(O)(O-i-Pr)₂}-3-{(P(O)(OH)₂}C₆H₂]P(O)Ph₂ ( 4 ). The reaction of ArLi with PhPCl₂ provided the benzoxaphosphaphosphole [1(P), 3(P)-P(O)(O-i-Pr)OPPh-6-t-Bu-4-P(O)(O-i-Pr)₂]C₆H₂P ( 5i ) as a mixture of the two diastereomers. The oxidation of 5i with elemental sulfur gave the benzoxaphosphaphosphole sulfide [1(P), 3(P)-P(O)(O-i-Pr)OP(S)Ph-6-t-Bu-4-P(O)(O-i-Pr)₂]C₆H₂ ( 5 ) as pair of enantiomers P1(R), P3(S)/P1(S), P3(R) of the diastereomer (RS/SR)- 5 ( 5b ). The aryldiphenylphosphane 5-t-Bu-1,3-[(P(O)(O-i-Pr)₂]₂C₆H₂PPh₂ ( 6 ) was obtained from the reaction of the corresponding aryldiphenylphosphane sulfide 2 with either sodium hydride, NaH, or disodium iron tetracarbonyl, Na₂Fe(CO)₄. The oxidation of the aryldiphenylphosphane 6 with elemental iodine and subsequent hydrolysis yielded the aryldiphenyldioxaphosphorane 9-t-Bu-2,6-(OH)-4,4-Ph₂-3,5-O₂-2,6-P₂-4λ⁵-P-[5.3.1.0]-undeca-1(10),7(11),8-triene ( 7 ). Both of its diastereomers, (RR/SS)- 7 ( 7a ) and (RS/SR)- 7 ( 7b ), were separated as their chloroform and i-propanol solvates, 7a ⋅2CHCl₃ and 7b ⋅i-PrOH, respectively. DFT calculations accompanied the experimental work.     

Strength of hydrogen bonding in the novolak-type phenolic resin blends

The specific interaction strength of novolak-type phenolic resin blended with three similar polymers [i.e., poly(ethylene oxide) (PEO), poly(ethylene glycol) (PEG), and poly(vinyl alcohol) (PVA)] were characterized by means of glass transition temperature behavior and Fourier transform infrared (FTIR) spectroscopy. The interassociation formed within phenolic blends with the addition of a modifier not only overcomes the effect of self-association of the phenolic upon blending, but also increases the strength of phenolic blend. The strength of interassociation within the phenolic blend is the function of the hydrogen bonding group of a modifier, in increasing order, is phenolic/PVA, phenolic/PEG, and phenolic/PEO blend, corresponding to the result of “q” value in the Kwei equation. The FTIR result is in agreement with the inference of T_g behavior. In addition, the fact that the specific strength of hydrogen bonding of hydroxyl–hydroxyl is stronger than that of hydroxyl–ether can also be concluded. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1721–1729, 1998     

Use of CaH2 as a reductive hydride source: reduction of ketones and imines with CaH2/ZnX2 in the presence of a Lewis acid

A new combination reagent of CaH₂/ZnX₂ effectively reduced a variety of ketones and imines to the corresponding alcohols and amines, respectively, in the presence of a catalytic amount of a Lewis acid such as Ti(O-i-Pr)₄, Al(O-i-Pr)₃, B(O-i-Pr)₃ and ZnF₂.     

Reactions of perfluorobenzocycloalkenes with ethyl cyanoacetate and methyllithium and some transformations of the products

Reactions of perfluorobenzocycloalkenes (Ar_FF) with methyllithium and ethyl cyanoacetate involved replacement of fluorine atoms in positions 3 and 4 of perfluorocyclobutabenzene, position 5 of perfluoroindan, and position 6 of perfluorotetralin by CH₃ and CH(CN)COOEt groups. Hydrolysis of the resulting esters Ar_FCH(CN)COOEt gave the corresponding perfluoroarylacetic acids Ar_FCH₂COOH which were converted into dichloroacetyl chlorides Ar_FCCl₂COCl by treatment with PCl₅. The reaction of Ar_FCCl₂COCl with SbF₅ produced trifluoromethyl derivatives Ar_FCF₃. Decarboxylation of Ar_FCCl₂COOH in DMF afforded dichloromethyl derivatives Ar_FCCl₂H which reacted with CsF on heating to form difluoromethyl analogs Ar_FCF₂H.     

Synthesis,structure and nonlinear optical properties of three dimensional compounds

The combination of metal ions with H₃tbba has resulted in the formation of two three dimensional coordination compounds {[Zn(H₂tbba)₂(H₂O)] · 2(OC₃H₆)} _n (1) and {[Mn(H₂tbba)₂(H₂O)] · 2(OC₃H₆)} _n (2) (H₂tbba = 2-thiobarbituric acid anion). Compounds 1 and 2 are isostructural with metal ions bridged by four hydroxyl oxygens from four different H₂tbba ligands to form a 3D network. H₂tbba exhibits bidentate coordination with both hydroxyl oxygens participating in coordination, a new coordination mode. Nonlinear absorption and refraction of 1 and 2 in DMF are studied by using Z-scan measurement technique at 532 nm. 1 and 2 possess nonlinear optical absorption and self-focusing.     

Synthesis,characterization and alcohol oxidation properties of multi-wall carbon nanotubes functionalized with a cobalt(II) Schiff base complex

A hydroxyl functionalized cobalt(II) Schiff base complex has been covalently anchored to modified multi wall carbon nanotubes (MWNTs). The modified MWNTs have been characterized by physico-chemical and spectroscopic methods. The results suggest that the symmetrical Schiff base, N,N′-bis(4-hydroxysalicylidene)-ethylene-1,2-diamine; H₂[((OH)₂-salen)] acts as a tetradentate N₂O₂ donor via the deprotonated phenolic oxygens and azomethine nitrogens. The functionalized [Co((OH)₂-salen)]–MWNTs catalyze the oxidation of aliphatic and aromatic alcohols into the corresponding carboxylic acids and ketones in the presence of 30% H₂O₂ in good yields. The system is truly heterogeneous (no leaching observed) and reusable (no decrease in activity over three consecutive runs).     

Dopant-assisted atmospheric pressure photoionization mass spectrometry of polyisobutylene derivatives initiated by mono- and bifunctional initiators

Nine polyisobutylene (PIB) derivatives with different end groups (chlorine, vinyl, isobutenyl, 2,2-diphenylvinyl, and carboxyl) and molecular weights (1000 to 4500 g/mol), initiated by monofunctional and aromatic bifunctional initiators were studied by atmospheric pressure photoionization mass spectrometry (APPI-MS) in both negative and positive ion modes. Consistent with previous findings, negative ion APPI-MS revealed end-group identities through the formation of PIB adducts with chloride ions formed in situ from a chlorinated solvent (e.g., CCl₄) in the presence of a dopant (toluene). In positive ion mode, considerable fragmentation of these PIB derivatives was observed, rendering end-group determinations very difficult. The M _n values obtained by APPI(−)-MS were considerably lower than those determined by SEC for PIB derivatives with M _n higher than 2000 g/mol. PIBs containing carboxyl termini can undergo collision-induced dissociation, yielding structurally important product ions. The resulting APPI-MS/MS intensities were found to reflect the “arm-length” distribution for PIBs with bifunctional aromatic moieties. In positive ion mode, [M+COCl]⁺ adducts were observed for PIBs with an aromatic initiator moiety. The origin of the COCl⁺ species is also discussed.