Presence Of Polyphosphoric Acid Research Articles

Analgesic activity of acylated 2-benzoxazolinone derivatives

Ten new benzoxazolinone derivatives having a disubstituted benzoyl group at the six position of the ring were synthesized by reacting 2-benzoxazolinone with aromatic carboxylic acids in the presence of polyphosphoric acid. The structure of the compounds were elucidated by IR, 1H NMR, MS and elemental analysis. Analgesic activity was evaluated by a modified Koster test. Seven compounds showed analgesic activities higher than that of acetylsalicylic acid.

SYNTHESIS OF NEW BENZO[e]DIBENZOFURO[2,3-b]-OXEPIN-5(14H)-ONES.

The new ring systems, benzo[e]dibenzofuro[2,3-b]oxepin-5(14H)-one and benzo[e]dibenzofuro[2,1-b]oxepin-5(14H)-one were obtained by cyclizing of 2-(2-dibenzoftuyloxymethyl)benzoic acid in the presence of polyphosphoric acid ester.By cyclization of the 2-(1-methoxy-2-dibenzofuryloxymethyl) benzoic acid was obtained benzo[e]dibenzofuro[2,3-b]-oxepin-12-methoxy-5-one with a indubitable structure. The structure of the new compounds was proved by means of 1H-and 13C-NMR spectra.

Synthesis and tautomerism of 2‐aryl‐ and 2‐heteroaryl derivatives of benzimidazole

AbstractBenzimidazoles containing furyl and thienyl substituents at C‐2 were prepared by condensation of o‐phenylenediamine and corresponding carboxylic acids in the presence of polyphosphoric acid. The 2‐heteroarylbenzimidazoles showed tautomerism in dimethyl sulfoxide solution while 2‐phenylbenzimidazole did not. The tautomerism appeared to be taking place by intermolecular relay of protons between stacked molecules.

Tandem Acylation-Cycloalkylation: A Novel Synthesis of Phenanthrenes

Cyclohexene-1-acetic acid (1) undergoes reactions with various aromatic substrates 2a-k in the presence of polyphosphoric acid (PPA) to give 1,2,3,4,4a,10a-hexahydrophenanthren-9(10H)-ones 3a-k by tandem acylation-cycloalkylation, which on dehydrogenation with Pd-C afforded the corresponding phenanthrenes 4a-k in high yields.

Reaction of phenols with cyclic α,β-unsaturated acids: An efficient one-pot synthesis of hexahydroxanthones

A number of 1,2,3,4,4a,9a-hexahydro-9H-xanthen-9-ones have been prepared by the reaction of various phenols with 1-cyclohexene-1-carboxylic acids in the presence of polyphosphoric acid (PPA). However the reaction of 2,3-dimethylphenol gave in addition two isomeric 6,7-dimethyl-dodecahydro-indeno (1,2-a)xanthen-8,13-diones. 2,5-Dimethylphenol reacted differently giving the hexahydro-9H-fluoren-9-one instead. Dehydrogenation of the hexahydroxanthones with Pd/C in refluxing diphenyl ether afforded the corresponding xanthones in good yields (80–95%).

A Simple Approach to the Synthesis of Fluoren-9-Ones

Abstract Cyclohexene-l-Carboxylic acid (I) undergoes reaction with various aromatic substrates (2a-i) in presence of Polyphosphoric acid (PPA) at 100[ddot]c to give cis-1,2,3,4,4a,9a - hexahydrofluoren-9-ones (3a-i) in good yield. Dehydrogenation of (3a-i) with selenium powder afforded corresponding fluoren-9-ones (4a-i) in high yield.

A one-step efficient general method for the synthesis of naphthopyrones: A first synthesis of spiro [naphthalene-2,4′-phenanthrene] carbocycles

A new synthesis of naphthopyrones and hexahydrospiro [naphthalene-2,4′-phenanthrene]-1,1′-diones has been accomplished by the Friedel-Crafts reaction of various 1-tetralones with α,β-unsaturated acids in the presence of polyphosphoric acid (PPA).

Physicochemical study of complexation and ion-exchange properties of 2-hydroxy-4-ethoxypropiophenone—ethylene glycol polymer

Copolymers (HEPP-EG) were synthesized by the condensation of 2-hydroxy-4-ethoxypropiophenone with ethylene glycol in presence of polyphosphoric acid as a catalyst. The copolymers were characterized by elemental analyses, IR spectra, viscosity and thermal studies. The number-average molecular weight (Mn) was measured by non-aqueous conductometric titration. The copolymer HEPP-EG-6 was complexed with metal ions, Cu2+, Ni2+, Co2, Mn2+ and Zn2+ and characterized. Chelation ion-exchange properties have been studied by employing the batch equilibration method.

Cyclization of 2‐methoxy‐6‐( substituted benzyloxy) acetophenone hydrazones in the presence of polyphosphoric acid (PPA)

AbstractCyclization of 2‐methoxy‐6‐benzyloxy acetophenone hydrazone gave 3‐methyl‐4‐methoxy indazole and 3‐methyl‐4‐methoxy‐7‐benzyl indazole in the presence of polyphosphoric acid (PPA). The hydrazone was probably converted to 2‐hydroxy‐6‐methoxy acetophenone hydrazone and 2‐hydroxy‐3‐benzyl‐6‐methoxy acetophenone hydrazone followed by cyclization to the corresponding indazoles in acidic conditions. Cyclization of 2‐methoxy‐6‐(halo or alky] or aryl benzyloxy) acetophenone hydrazones gave similar products. Cyclization of 2‐methoxy‐6‐(p‐nitrobenzyloxy) acetophenone hydrazone gave 2‐(p‐nitrophenyl)‐3‐methyl‐4‐methoxy benzofuran and 3‐methy]‐4‐methoxy indazole while 2‐methoxy‐6‐(m‐nitrobenzyloxy) acetophenone hydrazone gave 3‐methyl‐4‐methoxy indazole, 3‐methyl‐4‐methoxy‐7‐(m‐nitrophenyl) indazole and 3‐methyl‐4‐(m‐nitrobenzyloxy) indazole.

A new and facile synthesis of 1H-indazoles

A new and convenient procedure is described for the synthesis of 1H-indazoles by cyclization of 2,6-dialkoxyacetophenone hydrazones in the presence of polyphosphoric acid (PPA).

Synthesis of 3‐hetaryl‐4,5,6,7‐tetrahydrobenzo[b]thiophenes

AbstractA novel efficient synthesis of 3‐hetaryl‐4,5,6,7‐tetrahydrobenzo[b]thiophenes was achieved by the cyclocondensation of ethyl 2‐amino‐4,5,6,7‐tetrahydrobenzo[6]thiophene‐3‐carboxylate with selected o‐substituted aromatic amines or with alifatic, aromatic and heterocyclic acid hydrazides in the presence of polyphosphoric acid.

Novel selective heterocyclization of the Michael adducts of ene-hydrazines with dimethyl acetylenedicarboxylate

Cyclization of the Michael adducts 1 and 6 formed from ene-hydrazines and dimethyl acetylenedicarboxylate (DMAD) in the presence of polyphosphoric acid (PPA) produced the fused 1,2-diazepine rings 2 and 7. However, the adducts when heated in 1,2,3,4-tetrahydronaphthalene (tetralin) preferentially provided the fused pyridone rings 4 and 10 and the fused pyrrole rings 5 and 11.

Reinvestigation of Condensation of Resorcinol and β-Ketoester in the Presence of Polyphosphoric Acid. Synthesis of a Novel Coumarin Dimer

Reinvestigation of Condensation of Resorcinol and β-Ketoester in the Presence of Polyphosphoric Acid. Synthesis of a Novel Coumarin Dimer

Thermal Behaviors of Pitch-Anthraquinone Condensates

Pitch (CTP)-anthraquinone (AQ) and hydrogenated pitch (HCTP)-AQ condensates were prepared by reacting the pitch and AQ in the presence of polyphosphoric acid with various mixing ratios. The reaction mechanism of the pitch and AQ was investigated by use of some model compounds. These condensates obtained were characterized in terms of solubility for solvents, thermogravimetric analysis and observation of optical textures of the heat-treated products. The condensates prepared with a mixing ratio of 7/3-6/4 for CTP to AQ gave a maximum carbonization yield (76%) at 1000°C and the carbonized products showed a mozaic texture. In the case of HCTP-AQ, a comparable high yield and a similar texture were obtained for the condensate prepared with an equal amount of HCTP and AQ. It was found that the hydrogenation of pitch to be condensated with AQ is important to improve the solubilization of the condensates for solvents and also to develop the anisotropic textures. Both condensates with the high carbonization yield gave a large interlayer spacing of about 0.34nm on the heat-treatment up to 2200°C, but the graphitizability was considerably enhanced when they were heat-treated above 2500°C.

ChemInform Abstract: Fused Imidazo‐1,2,4‐azines. Part 21. Synthesis of 2‐Arylfuro(pyrrolo,thieno)(2′,3′:5,6)(1,2,4)triazino(2,3‐a)benzimidazoles by Cyclization of 2‐Aroylmethyl(1,2,4)triazino(2,3‐a)benzimidazol‐3(4H)‐ones.

AbstractCyclization of the aroylmethyltriazinobenzimidazolones (I) in the presence of polyphosphoric acid or phosphorus pentasulfide (III) gives the furo‐ (II) or thieno‐anellated products (IV).

ChemInform Abstract: Condensation of Phenols and Cinnamic Acids in the Presence of Polyphosphoric Acid: A Novel Biogenetic‐Type Oxidative Self‐Cyclization of p‐Methoxycinnamic Acid to 7‐Methoxycoumarin.

AbstractA series of title reactions between the phenol compounds (I) and (II) and the acids (III) are investigated.

Reactions of dialkoxynaphthalenes with cyclic α, β-unsaturated acids

Synthetically useful substituted hexahydrobenzofluoren-11-ones and tetrahydropentalenonaphthalen-10(H)-ones are prepared in one step by the reaction of cyclic α, β-unsaturated acids, namely, 1-cyclohexene.-1-carboxylic acid and 1-cyclopentene-1-carboxylic acid, with substituted dialkoxynaphthalenes in the presence of polyphosphoric acid. The stereochemistry at the C/D ring junction is determined from the1H NMR and by decoupling experiments.

ChemInform Abstract: Synthesis and Mass Spectroscopic Study of Benzo‐12‐crown‐4 Acyl Derivatives.

AbstractAcylation of the crown ether (I) with carboxylic acids (II) in the presence of polyphosphoric acid gives the monoacyl derivatives (III) or the twofold acylated derivatives (IV), depending on the molar ratio.

Alkylation of benzo- and dibenzocrown ethers by various alcohols

New alkyl derivatives of benzo-15-crown-5, benzo-18-crown-6, dibenzo-18-crown-6, dibenzo-24-crown-8, and dibenzo-30-crown-10 have been obtained by their alkylation with various alcohols in the presence of polyphosphoric acid.

Synthesis of 6‐phenyl and 6‐styrylthiazolo[3,2‐b] [1,2,4]triazoles

AbstractThiazole rings have been often encountered in the structure of antibiotic or antitumor drugs. An easy synthesis of them has revealed itself necessary in order to elucidate the mechanism of action of these naturally occurring substances. A method of preparation of conjugated b‐ethylenic thiazole[3,2‐b] [1,2,4]triazoles by heating a 3‐thio substituted [1,2,4]triazole in the presence of polyphosphoric acid is reported here, giving the expected product in a 60% yield.