Coordination Compounds of Copper(II) Nitrate with Products of Aminotris(hydroxymethyl)methane Condensation with Salicyl- and 5-Nitrosalicylaldehydes: Synthesis and Crystal Structures

The crystal structures of copper(II) nitrate complexes with 2-(2-hydroxybenzylideneamino)-2-hydroxymethylpropane-1,3-diol (HL) and 2-hydroxymethyl-2-(2-hydroxy-5-nitrobenzylideneamino)propane-1,3-diol (HL¹) were determined. The resulting complexes were formulated as [Cu₃OL₃(H₂O₂]NO₃ · 3H₂O (I) and [Cu(H₂O)L¹]NO₃ (II). The crystals of I are monoclinic, a = 17.809(4) Å, b = 30.549(6) Å, c = 18.962(4) Å, β = 115.36(3)°, space group Cc, Z = 8, R = 0.0482. Complex I is composed of two independent three-dimensional µ₃-oxo complexes; the coordination polyhedron of the copper atoms in both compounds is an elongated tetragonal bipyramid. The coordination polyhedron of the third Cu atom is a tetragonal pyramid. The bases of the pyramids are composed of the oxygen atoms of the phenol and alcohol OH groups, the imine N atom of ligand L, and µ ₃-oxo atoms. The phenol and water O atoms serve as the apices in both the tetragonal bipyramids. The crystals of II are triclinic, a = 6.062(1) Å, b = 7.701(2) Å, c = 16.162(3) Å, α = 88.15(3)°, β = 84.94(3)°, γ = 78.13(3)°, space group P1¯, Z = 2, R = 0.0272. Complex II is composed of polymer chains formed by coordination bonds between the copper atom and two O atoms of the amino alcohol in the azomethine of the neighboring complex connected to the initial one by translation along the x axis. These chains are linked through hydrogen bonds involving the oxygen atoms of the NO₂ groups. The benzene rings of the azomethine ligands of the adjoining complexes from different chains are antiparallel to each other. The coordination polyhedron of the central atom is an elongated tetragonal bipyramid. Its equatorial plane is formed by the phenol O atom, one of the alcohol O atoms, the N atom of ligand L¹, and the O atom of the amino alcohol in the neighboring complex. The apices are the O atom of the water molecule and the O atom of the amino alcohol in the neighboring azomethine molecule. In complexes I and II, the outer-sphere nitrato group mainly serves to unite trimers and polymers in the crystal by means of hydrogen bonds.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 8, 2005, pp. 621–629.Original Russian Text Copyright © 2005 by Chumakov, Tsapkov, Simonov, Antosyak, Bocelli, Perrin, Starikova, Samus, Gulea.     

Synthesis and tautomeric transformations of 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones

Treatment of 2-(tert-butyl)-1,2,3,4-benzotetrazinium tetrafluoroborates with sodium thiocyanate afforded 2-(tert-butylazo)phenyl isothiocyanates 3, which exist in equilibrium with 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones 3′. The equilibrium depends on the substituents R in the benzene ring: the percentage of the open isomer 3 is about 20% for R = H or Me; for R = Cl or Br, the equilibrium is completely shifted to cyclic isomer 3′. The equilibrium is slow on the time scale of the ¹H and ¹³C NMR experiments. For compounds 3a/3′a (R = H), the spectra at 24 °C show two sets of signals, while those at 0 °C contain only signals for isomer 3′a. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1192–1195, July, 2006.     

Determination of the active ingredients in Gastrodia rhizoma by capillary electrophoresis with electrochemical detection

A simple, reliable and reproducible method, based on capillary electrophoresis (CE) with electrochemical detection (ED), for the determination of five active ingredients and three carbohydrates in extracts of Gastrodia rhizoma is described in this work. The main active ingredients are gastrodin, 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin. Operated in a wall-jet configuration, a 300 microm diameter carbon disc electrode was used as a working electrode, with a good response at +1000 mV (vs. SCE) for 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin; a 300 microm diameter copper disc electrode exhibits a good response at +650 mV (vs. SCE) for gastrodin, sucrose, glucose and fructose. Under optimum conditions, 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin in 100 mmol l(-1) borate buffer (pH 9.2) and gastrodin, sucrose, glucose and fructose in 50 mmol l(-1) sodium hydroxide buffer were baseline separated within 18 min. The response was linear over two orders of magnitude with a detection limit (S/N = 3) in the range 3 x 10(-7)-1.8 x 10(-6) mol l(-1) for all eight analytes. This method was successfully used in the analysis of traditional Chinese medicine, and the assay results were satisfactory.     

Chiral Recognition of Propranolol with <Emphasis Type="Bold">β</Emphasis>-Cyclodextrin in the Presence of 1- and 2-Butanol

The purpose of this work is to investigate the chiral recognition characteristics of β-cyclodextrin with two propranolol enantiomers in the presence of organic additives. Steady-state fluorescence measurements of propranolol β-cyclodextrin (β-CD) complexes were performed for solutions containing either 1- or 2-butanol. For each 2-butanol isomer solution, the interactions were assessed by comparing the changes in the fluorescence of (R)-(+)- propranolol versus (S)-(-)-propranolol as a function of CD concentration. A similar comparison study was done for the propranolol enantiomers in the presence of 1-butanol. The intensity changes for propranolol are relatively small upon addition of β-CD in the presence of the butanol alcohol. However, the present work shows that the interaction of (R)-(+)-propranolol with β-CD is influenced by the chirality of 2-butanol in contrast to (S)-(-)-propranolol.This revised version was published online in July 2005 with a corrected issue number.     

Syntheses of (±)-17α- and (±)-17β-hydroxytacamonine; determination of configuration at C-17

Both (±)-17α-hydroxytacamonine (3) and its 17β-isomer (4) were synthesized in two steps (one-pot) from aldehyde mixture 5/6 via the cyanohydrin reaction. NMR spectral characterization of isomer 3 revealed it to be unidentical with natural 17-hydroxytacamonine, whereas spectral data of isomer 4 were in agreement with those published for the natural isomer. The configuration at C-17 was confirmed by NOE difference spectroscopy.     

镧系盐催化合成辣椒酯衍生物研究

对比研究了三氯化铕,三氯化镧,三氯化铈和三氯化镨四种镧系盐催化剂化学选择酯化香草醇收率的影响。以三氯化镧为化学选择催化剂,且香草醇与三氯化镧物质的量比为1：0.005时,癸酸香草醇酯的收率最高为85%,并用该法合成辛酸香草醇酯和月桂酸香草醇酯,其收率分别为87%和71%。     

F-Induced decomposition of 3-[(3-tert-butyldimethylsiloxy)phennoxy]-3-phenyl-1,2-dioxetanes without CC bond cleavage of the dioxetane ring

F⁻-induced decomposition of 3-[3-(tert-butyldimethylsiloxy)phenoxy]-3-phenyl-1,2-dioxetane (5c) yielded an intramolecular redox product (7b), whereas 3-phenoxy-3-(3-siloxyphenyl)-1,2-dioxetane (3) gave normal carbonyl fragments with intense light emission. An isomer (5a) gave light with normal decomposition by CIEEL, though the major process was one to yield an acyloin (7a).     

An Extractive Spectrophotometric Method for the Determination of Nitrite Using Fluorescein Amine Isomer I

ABSTRACT

A sensitive spectrophotometric method for the determination of nitrite using fluorescein amine isomer I is described. The method is based on the formation of azido derivative of fluorescein amine isomer I, which is selectively extracted into 20% iso amyl alcohol in toluene and is stripped to aqueous phase using NaOH. Formation of the azido derivative depends on nitrite concentration and the system obeys Beer's law in the range 0-0.4 ppm of nitrite at 495 nm. The molar absorptivity of the colour system is 6.67 × 10⁴ L mol^-1 cm^-1 with a relative standard deviation of 3% for 10 determinations at 1 μg of nitrite. The proposed method is successfully applied for the determination of nitrite and nitrate in soil, water and radiator coolant sample, NO₂ gas in a laboratory fume cupboard is determined after fixing it as nitrite in sodium arsenite absorber solution.     

Theoretical study on structures and stability of HC2P isomers

 The structures and isomerization pathways of various HC₂P isomers in both singlet and triplet states are investigated at the B3LYP/6-311G(d,p), QCISD/6-311G(d,p) (for isomers only) and single-point CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p) levels. At the CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p) level, the lowest-lying isomer is a linear HCCP structure ³ 1 in the ³∑⁻ state. The second low-lying isomer has a CPC ring with exocyclic CH bonding ¹ 5 in a singlet state at 10.5 kcal/mol. The following third and fourth low-lying isomers are a singlet bent HCCP structure ¹ 1 at 20.9 kcal/mol and a bent singlet HPCC structure ¹ 3 at 35.8 kcal/mol, respectively. Investigation of the HC₂P potential-energy surface indicates that in addition to the experimentally known isomer ³ 1, the other isomers ¹ 1, ¹ 3 and ¹ 5 also have considerable kinetic stability and may thus be observable. However, the singlet and triplet bent isomers HCPC ¹ 2 and ³ 2 as well as the triplet bent isomer HPCC ³ 3 are not only high-lying but are also kinetically unstable, in sharp contrast to the situation of the analogous HCNC and HNCC species that are both kinetically stable and that have been observed experimentally. Furthermore, the reactivity of various HC₂P isomers towards oxygen atoms is briefly discussed. The results presented here may be useful for future identification of the completely unknown yet kinetically stable HC₂P isomers ¹ 1, ¹ 3 and ¹ 5 either in the laboratory or in interstellar space. Received: 5 November 2000 / Accepted: 25 November 2001 / Published online: 8 April 2002     

Reaction of ruthenacarborane with trifluoroacetoxymercuroferracarborane

The reaction of exo-nido-ruthenacarborane exo-nido-5,6,10-[Cl(Ph₃P)₂Ru]-5,6,10-(-H)₃-10-H-7,8-C₂B₉H₈ (1) with the 8-trifluoroacetoxymercury derivative of ferracarborane 3-(⁵-Cp)-4-SMe₂-8-CF₃COOHg-3,1,2-FeC₂B₉H₉ (2) was studied. It was demonstrated for the first time that metallacarborane 2 can be used as a mercurating agent. The reaction afforded 5",6",10"-exo-nido-[Cl(Ph₃P)₂Ru]-5",6",10"-(-H)₃-10"-{3-(⁵-Cp)-4-SMe₂-3,1,2-FeC₂B₉H₉-8-Hg}-7",8"-C₂B₉H₈ (3) existing as two isomers. The structure of trans isomer 3a was established by X-ray diffraction analysis.     

Synthesis of 3-Ethoxy-2-Oxo-3-Phenyl-1,2-Oxaphosphorinane-3,5-Diene

Abstract

In view of the limited number of examples of 2-oxo-l,2-oxaphosphorinane3,5diene derivatives^1,2, we investigated the preparation of the title compound and derivatives of the same. Of additional interest were the spectroscopic propertits of this class of compounds, their stability, and the outcome of their reaction with nucleophilts. Prior work in our laboratory on the synthesis of simple phostones and their derivatives³, led us to use these as starting mataials. The presence of the phenyl substituent in la, (cis and trans isomers) permitted facile introduction of a bromo group through free radical bromination with NBS/AIBN to give 2a,b in 79% overall yield. The individual isomers of 2 were separated; tentative stereochemical assignments were made using NMR spectroscopy. Treatmnt of 2 with LiCl/DMF gave 3; the trans isomer (phenyl and OEt trans) 2b reacted much faster than the cis isomer. Treatmnt of 3 with NBS/AIBN gave 4a,b and 5 which were separated by flash chromatography. Dehydrobromination of 4 (71% yield) was achieved by heating with an excess of Et₃N in toluenc at 95°C to produce 6; likewise, dehydrobromination of 5 at 70°C gave 7.     

Solvent Influence on the Transformation of Intramolecular Hydrogen Bonds in 2-Hydroxy-5-Methyl-3-Nitroacetophenone

DFT (B3LYP/6-31+G(d,p)) calculations performed on 2-hydroxy-5-methyl-3-nitroacetophenone (I) indicate that the isomer with the intramolecular hydrogen bond (IMHB) to the nitro group (Ia) is more stable by 7.3 kJ-mol⁻¹ than that with the H-bond to the acetyl group (Ib). The calculated polarities of both isomers are quite different with the dipole moment of Ib being five times higher. Dipole moment and infrared studies of the Ia ⇌ Ib conformational equilibrium in different solvents show that the IMHB transformation is controlled by the solvent polarity. In polar dichloromethane and acetonitrile the Ia ⇌ Ib equilibrium is strongly shifted towards the polar Ib isomer. The simple continuum dielectric model for a heterogeneous medium and polarizable solute allows a quantitative explanation of the influence of the solvent on the Ia ⇌ Ib equilibrium.     

Studies on the radical addition reaction of perfluoroalkyl iodides with 2,3-allenols and the Pd-catalyzed kinetic resolution via Sonogashira coupling reaction

A radical addition reaction promoted by Na₂S₂O₄ of perfluoroalkyl iodides with 2,3-allenols affording E/Z mixtures of 3-iodo-4-perfluoroalkyl-substituted allylic alcohols has been studied. Kinetic resolution with Sonogashira coupling reaction was applied to afford the Z isomer of 3-iodo-4-perfluoroalkyl-substituted allylic alcohol (Z-3) and the E isomer of conjugated enynic diols (E-5) in 39-52% and 22-40% yields, respectively.     

Synthesis of enantiomers of 2′-aminomethyl-5-benzylacyclouridine (AM-BAU) and 2′-aminomethyl-5-benzyloxybenzylacyclouridine (AM-BBAU). Potent inhibitors of uridine phosphorylase

Racemic 2′-aminomethyl-5-benzyl-acyclouridine (AM-BAU, 5 ) and 2′-aminomethyl-5-benzyloxybenzyla-cyclouridine (AM-BBAU, 6 ) have been found to be very active inhibitors of uridine phosphorylase [1]. Their enantiomers were synthesized from chiral 2,2-dimethyl-1,3-dioxolane-4-methanol ( 7a,b ). S-(—)-AM-BAU ( 5a ) and S-(—)-AM-BBAU ( 6a ) were prepared from the R-(—) isomer 7a , and R(+)-AM-BAU ( 5b ) and R-(+)-AM-BBAU (6b) from the S-(+) isomer 7b . A different route from the S-(+) isomer 7b to S-(—)-AM-BBAU ( 6a ) was also determined to be feasible.     

Furopyridines. II. Bromination and nitration of furo[2,3-b]-, furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine

In order to reveal the reactivities of furopyridines, we undertook bromination and nitration of four furopyridines ( 1, 2, 3 and 4 ) whose chemical properties had been almost unknown. Bromination of 1, 2, 3 and 4 gave the corresponding trans-2,3-dibromo-2,3-dihydro derivatives 6, 8, 10 and 12 , respectively, which were converted to 3-bromofuropyridines 7, 9, 11 and 13 by treatment with sodium hydroxide in aqueous methanol. Nitration of 1 with a mixture of fuming nitric acid and sulfuric acid afforded a mixture of addition products 14a, 14b and 14c and 2-nitro derivative 15 . Both 14a and 14b were easily converted to 15 by treatment with sodium bicarbonate. Compound 2 was nitrated to give a mixture of cis- and trans-2-nitro-3-hydroxy-2,3-dihydro derivative 16a and 16b and 2-nitro derivative 17 . The cis isomer 16a was transformed to the trans isomer 16b by refluxing on silica gel in ethyl acetate. Compound 16b was dehydrated with acetic anhydride to give 17 . Nitration of 3 gave a nitrolic acid derivative 20 . Nitration of 4 gave a mixture of 2-nitro derivative 22 and 3-(trinitromethyl)pyridin-4-ol ( 23 ). The structures of 20 and 23 were established by single crystal X-ray analysis. The differences of behavior observed in these reactions are discussed in connection with the results of the determination of pKa values and the relative reactivities of deuteriodeprotonation of these furopyridines.     

Dual-functional,aromatic, epoxy-methacrylate monomers from bio-based feedstocks and their respective epoxy-functional thermoplastics

Dual-functional monomers consist of two distinctly different functional groups that enable chemical versatility. The most readily available epoxy-methacrylate dual-functional monomer is glycidyl methacrylate (GMA). In an effort to produce bio-based, aromatic complements to GMA, asymmetric phenolic diols (vanillyl alcohol, syringyl alcohol, gastrodigenin, and tyrosol) were identified and selectively epoxidized at the aromatic hydroxyl followed by subsequent esterification at the aliphatic hydroxyl to prepare dual functional monomers, vanillyl alcohol epoxy-methacrylate (VAEM), syringyl alcohol epoxy-methacrylate (SAEM), gastrodigenin epoxy-methacrylate (GDEM), and tyrosol epoxy-methacrylate (TEM). These monomers are viable platforms for a multitude of applications due to their unique chemical functionalities. VAEM, SAEM, GDEM, and TEM were homopolymerized individually to produce aromatic, bio-based epoxy-functional thermoplastics analogous to poly(GMA). The molecular weight distributions and thermal properties of each polymer were evaluated, as were the surface characteristics of flow-coated thin films from these polymers. Most of the newly prepared epoxy-functional thermoplastics exhibited increased thermal stability (initial decomposition temperatures >260 °C in air) relative to poly(GMA), while retaining similar glass transition temperatures (~ 65 °C) and surface energies (~ 53 mJ m⁻²); thus, these materials could be substituted for poly(GMA) and enable use in higher-temperature applications. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 673–682     

Structure and reactivity of α,β-unsaturated ethers—XIV: Protonation of cis- and trans-1-ethoxybuta-1,3-dienes

The acid-catalysed hydrolysis and alcohol addition of cis- and trans-1-ethoxybuta-1,3-dienes have been investigated. It was found by product analyses with deuterium incorporation experiments that in both the reactions the cis isomer protonates at the 2-position as well as at the 4-position while the trans isomer protonates exclusively at the 4-position. The kinetic experiments showed that the trans isomer is much more reactive than the cis isomer. The possible origin of the observations is discussed.     

Synthesis of Repaglinide Congeners

This report describes a synthesis of two potent impurities of repaglinide, benzyl repaglinide 1 and repaglinide isomer 2, from commercially available raw materials: 2-fluoro benzonitrile, (S)-3-methyl-1-[2-(piperidin-1-yl)phenyl]butylamine (5), and 3-ethoxy-[4-(ethoxycarbonyl)phenyl]acetic acid (7). These impurities are the crucial components in determining the quality of the drug substance, repaglinide, during its manufacturing.     

Lanthanide chemical shift reagents as tools for determining isomer distributions in 2,4-hexadienoates and related compounds

Quantitative analysis of geometrical isomers of unsaturated esters and alcohols is facilitated with Eu(fod)₃. Commercial sorbic acid exists in the all-trans form, while sorbyl alcohol contains c. 10% of the cis-4,5 isomer.     

Structure and Stability of Isomers of the Promising Interstellar Molecule PC3O

DFT/B3LYP/6-311G(d) and CCSD(T)/6-311G(2d) single-point calculations are carried out for exploring the doublet potential energy surface (PES) of PC₃O, a molecule of potential interest in interstellar chemistry. A total of 29 minima connected by 65 interconversion transition states are located. The structures of the most relevant isomers and transition states are further optimized at the QCISD level followed by CCSD(T) single-point energy calculations. At the CCSD(T)/6-311G(2df)//QCISD/6-311G(d)+ZPVE level, the global minimum is the quasi-linear structure PCCCO 1 (0.0 kcal/mol) with a great kinetic stability of 47.9 kcal/mol, and the cumulenic form features largely in its resonance structures. Moreover, the chainlike isomer OPCCC 3 (64.5) and five-membered-ring species cPCCCO 19 (77.8) possess considerable kinetic stability of about 18.0 kcal/mol. All these three isomers are very promising candidates for future experimental and astrophysical detection. Additionally, a three-membered-ring isomer CC-cCOP 10 (69.6) has slightly lower kinetic stability of around 15 kcal/mol and may also be experimentally observable. Possible formation mechanisms of the four stable isomers in interstellar space are discussed. The present research is the first attempt to study the isomerization and dissociation mechanisms of PC _n O series. The predicted spectroscopic properties, including harmonic vibrational frequencies, dipole moments and rotational constants for the relevant isomers, are expected to be informative for the identification of PC₃O in laboratory and interstellar medium.