Photochemistry of halogenated benzene derivatives. Part VIII. Photoformation of 2-methyl-4,5,6,7-tetrachlorobenzoxazole from pentachlorophenol in water–acetonitrile

1987 ◽  
Vol 65 (9) ◽  
pp. 2223-2233 ◽  
Author(s):  
Ghulam Ghaus Choudhry ◽  
Norma Jean Graham ◽  
G. R. Barrie Webster
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Yield ◽  
Polarization Transfer ◽  
Benzene Derivatives ◽  
Mass Spectral Fragmentation ◽  
Molecular Ion ◽  
Mass Spectral ◽  
Methanolic Solution ◽  
H Nmr ◽  
C Nmr

Photolysis of a solution of pentachlorophenol (1) in H2O–CH3CN (2:3 v/v) was conducted on a synthetic scale using wavelengths ≥290 nm. After changing the pH of the photolyzate of 1 to ≥12, the photoproduct 2-methyl-4,5,6,7-tetrachloro-benzoxazole (2) was extracted with n-hexane. The product 2 was crystallized from methanolic solution. Ultraviolet, IR, FT-1H-NMR, proton-decoupled normal FT-13C-NMR, and proton-decoupled DEPT (distortionless enhancement by polarization transfer) sequence FT-13C-NMR spectroscopy were used to identify photoproduct 2 as 2-methyl-4,5,6,7-tetrachlorobenzoxazole. A mechanism for the photoformation of benzoxazole 2 from 1 is proposed. 3,4,5,6-Tetrachlorocyclohexa-3,5-diene-1,2-ketocarbene formed from 2-hydroxy-3,4,5,6-tetrachlorophenyl radical is suggested as key intermediate involved in the generation of oxazole 2 from phenol 1. The chemical yield of 2 on the basis of 1 was ca. 1%. A mechanism is proposed to explain the mass spectral fragmentation of 2 via the losses of Ċl,:C=O, Cl—Ċ=O, CH3—Ċ=O, CH3CN, and C3H3ClNO species from the parent molecular ion.

Triazolopyridine nucleosides. II. Glycosylations of 3-oxo-s-triazolo[4,3-a]pyridines with accompanying conversions into 2-oxo-s-triazolo[1,5-a]pyridine nucleosides

1977 ◽  
Vol 55 (5) ◽  
pp. 831-840 ◽  
Author(s):  
Brian Maurice Lynch ◽  
Suresh Chandra Sharma
Keyword(s):  
General Structure ◽  
Spectroscopic Properties ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
H Nmr ◽  
Pyridine Nitrogen ◽  
Methyl Derivatives ◽  
Fragmentation Patterns ◽  
Ribose Moiety ◽  
C Nmr

3-Oxo-s-triazolo[4,3-a]pyridine and various C-methyl derivatives (general structure 1) have been converted into the 2-β-D-ribofuranosyl species 2 and thence 4 via Friedel–Crafts catalyzed reaction with tetra-O-acetyl-β-D-ribofuranose, followed by deblocking. During the course of these reactions, rearrangements into the isomeric 3-β-D-ribofuranosyl-2-oxo-s-triazolo[1,5-a]-pyridines occur through ring-opening of the pyridine rings yielding species 3 and 5. The proportion of rearrangement products is dependent upon the position and number of the C-methyl substituents.Structural assignments for these compounds are based upon comparisons of spectroscopic properties (1H nmr, 13C nmr, uv) with model compounds from each isomeric series; structural assignments for these models are based on unequivocal mass-spectral fragmentation patterns. Unlike related triazolopyridine nucleosides with the ribose moiety attached to a pyridine nitrogen (Lynch and Sharma (1976)), there are no unusual aspects in the conformations of the nueleosides of types 4 and 5.

Synthesis and Pharmacological Activities of Some New 2-[1-Heptyl-3-(4- methoxybenzyl)-5-oxo-1,5-dihydro-4H-1,2,4-triazol-4-yl]acetohydrazide Derivatives

2014 ◽  
Vol 69 (9-10) ◽  
pp. 969-981 ◽  
Author(s):  
Olcay Bekircan ◽  
Emre Mentese ◽  
Serdar Ulker
Keyword(s):  
Nmr Spectroscopy ◽  
Elemental Analysis ◽  
Lipase Activity ◽  
Spectral Studies ◽  
Antituberculosis Activity ◽  
Pharmacological Activities ◽  
Mass Spectral ◽  
H Nmr ◽  
Acetohydrazide Derivative ◽  
C Nmr

Abstract In the present investigation, the key intermediate acetohydrazide derivative 5 was synthesized starting from 3-(4-methoxybenzyl)-4-amino-4,5-dihydro-1,2,4-triazol-5-one (1) by a four-step reaction. Thiosemicarbazides 6a-f and arylidenehydrazide derivatives 8a-d were obtained from compound 5. The cyclization of compounds 6a-f in the presence of NaOH resulted in the formation of compounds 7a-f. The compounds were characterized by IR, 1H NMR, 13C NMR spectroscopy, elemental analysis and mass spectral studies. The compounds were tested for their anti-lipase, anti-α-glucosidase and anti-mycobacterial activities. Compounds 6b and 8c exhibited excellent anti-lipase activity, and compound 8d showed excellent anti-a-glucosidase activity. Compounds 3 and 4 exhibited good antituberculosis activity

Zirconocene-mediated selective synthesis of 1,4-bis(alkynyl)benzenes

2020 ◽  
Vol 44 (9-10) ◽  
pp. 571-575
Author(s):  
Bo Zhang ◽  
Hongmei Qu ◽  
Zhongxuan Li ◽  
Yuanyuan Zhai ◽  
Xiaolu Zhou ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dimethyl Ester ◽  
Acid Ethyl Ester ◽  
Coupling Reactions ◽  
Benzene Derivatives ◽  
Phenylene Ethynylene ◽  
H Nmr ◽  
Vis Spectroscopy ◽  
High Yields ◽  
C Nmr

A series of novel 1,4-bis(alkynyl)benzene derivatives were synthesized from trimethylsilyl-substituted alkynes by the mediation of zirconocene with excellent regioselectivity in high yields. The 3,6-bis(trimethylsilyl)-4,5-dialkylphthalic acid dimethyl esters were prepared by cycloaddition of 2,5-bis(trimethylsilyl)zirconacyclopentadienes to dimethyl acetylenedicarboxylate. After iodination with iodine monochloride, 3,6-diiodo-4,5-dialkylphthalic acid dimethyl esters reacted with terminal alkynes to prepare the corresponding 1,4-bis(alkynyl)benzene derivatives by Sonogashira coupling reactions. After removal of trimethylsilyl, 4,5-dibutyl-3,6-bis(ethynyl)phthalic acid dimethyl ester (compound 3) reacted with 4-iodobenzoic acid ethyl ester and 2-iodothiophene, respectively, to obtain the corresponding products 4a and 4c. Compound 3 can be extended to higher oligomers, which reacted with 1-bromo-4-iodobenzene and phenylacetylene in a stepwise manner under Sonogashira conditions to give the phenylene-ethynylene oligomer 5 in an isolated yield of 85%. The structures of the products were confirmed by 1H NMR spectroscopy, 13C NMR spectroscopy, and MS. The optical properties of the 1,4-bis(alkynyl)benzene derivatives were studied by UV-Vis spectroscopy and fluorescence spectra. The results indicated that some can be developed into potential photovoltaic materials.

scholarly journals NMR and Mass Spectroscopic Studies on Catharine

1985 ◽  
Vol 40 (4) ◽  
pp. 543-545 ◽  
Author(s):  
◽  
Irshad Ali ◽  
M. Iqbal Chaudhary
Keyword(s):  
Room Temperature ◽  
Spectroscopic Studies ◽  
Temperature Dependent ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
H Nmr ◽  
Temperature Dependent Study ◽  
C Nmr

The 13C NMR of Catharine is reported. A temperature-dependent study of the 1H NMR of Catharine indicates that it exists as two conformers at room temperature. At higher temperatures, the distinction between the two conformers disappears with the higher rate of equilibration. The mass spectral fragmentation of Catharine as established by link scan measurements is also re­ported.

Synthesis, Characterization and Complexation Studies with K + and Ca2+ Cations of trans-1.2-Cyclohexanedioxydiacetamides

1988 ◽  
Vol 43 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Whei Oh Lin ◽  
Maria C. B. V. de Souza ◽  
Helmut G. Alt
Keyword(s):  
Nmr Spectroscopy ◽  
Mass Spectroscopy ◽  
H Nmr ◽  
Coordination Sites ◽  
Complexation Studies ◽  
Ir And Nmr Spectroscopy ◽  
Elemental Analyses ◽  
C Nmr

The synthesis of trans-1.2-cyclohexanedioxydiacetamides starting with trans-1.2-cyclohexane-diol is described. Eleven of these compounds are characterized by IR, 1H NMR, 13C NMR and mass spectroscopy as well as elemental analyses. Most of these compounds are suitable ionophors for the cations K+ and Ca2+. The coordination sites of these ligands in the 1:2 complexes were determined by IR and NMR spectroscopy

[Zn(phen)2(CX3COO)]+, X = H orCl; Influence of X on the Coordination Mode of the Carboxylate Group (phen = 1,10-Phenanthroline)

2005 ◽  
Vol 60 (10) ◽  
pp. 1049-1053 ◽  
Author(s):  
Zeanab Talaei ◽  
Ali Morsali ◽  
Ali R. Mahjoub
Keyword(s):  
Nmr Spectroscopy ◽  
Elemental Analysis ◽  
Coordination Mode ◽  
Bidentate Ligand ◽  
Carboxylate Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Coordinate Geometry ◽  
C Nmr

Two new ZnII(phen)2 complexes with trichloroacetate and acetate anions, [Zn(phen)2(CCl3COO)- (H2O)](ClO4) and [Zn(phen)2(CH3COO)](ClO4), have been synthesized and characterized by elemental analysis, IR, 1H NMR, 13C NMR spectroscopy. The single crystal X-ray data of these compounds show the Zn atoms to have six-coordinate geometry. From IR spectra and X-ray crystallography it is established that the coordination of the COO− group is different for trichloroacetate and acetate. The former acts as a monodentate whereas the latter acts as a bidentate ligand.

scholarly journals Three-Dimensional Supramolecular Network Directed by Intermolecular Interactions in [Pb2(dmp)2(hfacac)4]

2009 ◽  
Vol 6 (4) ◽  
pp. 1085-1090
Author(s):  
Farzin Marandi ◽  
Lotfali Saghatforoush ◽  
Hossein Farzaneh
Keyword(s):  
Crystal Structure ◽  
Nmr Spectroscopy ◽  
Three Dimensional ◽  
Supramolecular Network ◽  
Stacking Interactions ◽  
H Nmr ◽  
Noncovalent Bond ◽  
Donor And Acceptor ◽  
Anionic Ligands ◽  
C Nmr

To investigate the interactions between noncovalent bond donor and acceptor giving rise to three dimensional networks, compound [Pb2(dmp)2(hfacac)2] (1) (dmp = 2,9-dimethyl-1,10-henanthroline and Hhfacac = hexafluoroacetylacetonate) has been prepared and characterized by elemental analysis, IR,1H NMR, and13C NMR spectroscopy and its crystal structures was investigated. The single crystal structure show the coordination number of Pb(II) to be eight with twoN-donor atoms from a “dmp” ligand and sixO-donors from the anionic ligands. The supramolecular structure of 1 is realized by weak directional C–H∙∙∙O–C, C–F∙∙∙F–C andπ–πstacking interactions.

Synthesis of isothiocyanates from non-aromatic nitrogen-containing heterocycles

1986 ◽  
Vol 51 (1) ◽  
pp. 112-117 ◽  
Author(s):  
Jozef Gonda ◽  
Pavol Kristian ◽  
Ľubomír Mikler
Keyword(s):  
Spectral Methods ◽  
Mass Spectral ◽  
H Nmr ◽  
C Nmr

Investigation of the reaction of thiophosgene with Δ2-oxazolines I, Δ3-thiazolines II, 4H-benzo[d][1,3]thiazines III, 2-methoxypentahydro-Δ1-azepine IV, theophylline and caffeine showed that only compounds I and IV reacted to give 2-acyloxyethyl isothiocyanates and methyl 6-isothiocyanatohexanoate. The structure of these products was corroborated by IR, 1H NMR, 13C NMR and mass spectral methods. The suitability of the above-mentioned compounds to react is discussed.

scholarly journals Synthesis of cis, cis-1,3,5-trisubstituted cyclohexane based chelators with polyfunctional pendant arms

2005 ◽  
Vol 2005 (1) ◽  
pp. 43-45 ◽  
Author(s):  
Minati Baral ◽  
B.K. Kanungo ◽  
Peter Moore
Keyword(s):  
Schiff Base ◽  
Nmr Spectroscopy ◽  
Organic Compounds ◽  
Elemental Analysis ◽  
H Nmr ◽  
Benzenetricarboxylic Acid ◽  
New Compounds ◽  
Pendant Arms ◽  
C Nmr

Some novel organic compounds of the type: cis, cis-1,3,5-tris(X)cyclohexane, where X= –CONH(CH2)2NH2, –CONH(CH2)3NH2, –CONH(CH2)2NCH –C6H4OH, CONH(CH2)3NCHC6H4OH, which are expected to function as potential polydentate chelators have been synthesised from 1,3,5-benzenetricarboxylic acid through multi-steps reactions. 1,3,5-benzenetricarboxylic acid was reduced to cis, cis-1,3,5-tris(ethylcarboxylate)cyclohexane, which on reaction with excess of 1,2-diaminoethane and 1,2-diaminopropane afforded two new compounds. Condensation of the obtained derivatives with three equivalents of salicylaldehyde resulted the formation of two new Schiff base compounds. All the compounds were characterised by a combination of elemental analysis, mass, IR, UV-Vis, 1H NMR and 13C NMR spectroscopy.

scholarly journals Isomeric Di-C-glycosylflavones in Fig (Ficus carica L.)

1985 ◽  
Vol 40 (1-2) ◽  
pp. 8-12 ◽  
Author(s):  
Fred Siewek ◽  
Karl Herrmann ◽  
Lutz Grotjahn ◽  
Victor Wray
Keyword(s):  
Nmr Spectroscopy ◽  
Reversed Phase ◽  
Ficus Carica ◽  
Preparative Hplc ◽  
H Nmr ◽  
Gradient Hplc ◽  
C Nmr

Two isomeric C-glycosides of apigenin (apigenin-6-C-glucosyl-8-C-arabinoside (schaftoside), apigenin-6-C-arabinosyl-8-C-glucoside (isoschaftoside)) were isolated from leaves of Ficus carica with preparative HPLC. 1The glycosides were identified by UV-, 1H-NMR-, 13C-NMR-spectroscopy and FAB-MS. Their concentration in fruits and leaves were determined by gradient HPLC on reversed phase material.

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