Condensation of 2-aminophenols and α-dicarbonyl compounds. Part 3. Benzoxazines substituted with heterocycles

A series of 1,4-benzoxazines (I) and 2,2′-dibenzoxazolines (II) were obtained by condensation of 2-aminophenol and 2-amino-5-nitrophenol with glyoxal derivatives of the heterocyclic series. The structure of compounds (I) was investigated by uv, pmr and mass spectroscopy.     

Condensation of 2-aminophenols and α-dicarbonyl compounds. Part 4. Dibenzoxazolines substituted with heterocycles

The tautomeric structure of 2,2′-dibenzoxazolines 2′-substituted with heterocycles was investigated by ir, pmr and uv spectroscopy.     

Synthesis and structure elucidation of N-methyl-4-(2-benzo-γ-pyronyl)-1,2,3-triazoles

When diazomethane was reacted with 2-cyano chromones, three isomeric N-methyltriazoles were obtained. They were isolated by liquid chromatography with three different solvents for elution. Complete elucidation of the structures was performed both by pmr and cmr spectrography; X-ray analysis is in agreement with the proposed structures.     

Condensation of o-aminophenol and α-dicarbonyl compounds. Part 2. Dibenzoxazolines

The study of 2′-aryl-2,2′-dibenzoxazolines (II), obtained together with 2-hydroxy-(2H)-1,4-benzoxazines (1) by condensation of o-aminophenol with a series of phenylglyoxal derivatives, emphasized that these compounds are an equilibrium mixture of dibenzoxazolines and related tautomeric ketimine forms. This behaviour was widely investigated by ir, uv and pmr spectroscopy. J. Heterocyclic Chem., 14, 957 (1977)     

Synthesis and antihypertensive properties of a novel series of 3-substituted amino-s-triazolo[3,4-α]phthalazine derivatives

A novel series of 3-substituted amino-s-triazolo[3,4-a]phthalazine derivatives has been synthesized by the one-pot cyclodesulfurization reactions utilizing 1-hydrazinophthalazine, alkyl, aryl, or aralkylisothiocyanates and dicyclohexylcarbodiimide (DCCD) mixtures. The products did not exhibit any antihypertensive properties. Their pmr and mass spectral analysis is given.     

Condensation of o-aminophenol and α-dicarbonyl compounds. Part 1. Benzoxazines

By condensation with o-aminophenol of a series of phenylglyoxal derivatives two species of products were obtained, namely 2-hydroxy-(2H)-1,4-benzoxazines (I) and 2′ -aryl-2,2′ -dibenzoxa-zolines (II). The structure of compounds I was investigated by ir, uv and pmr spectroscopy and a reaction mechanism was proposed. J. Chem. Soc., 14, 997 (1977)     

The synthesis and PMR study of certain 3-substituted 2-(β-D-Ribofuranosyl)indazoles

The synthesis of 3-cyano-2-(β-D-ribofuranosyl)indazole (4) has been accomplished by a condensation of N-trimethylsilyl-3-cyanoindazole (1) with 2,3,5-tri-O-aeetyl-D-ribofuranosyl bromide (2) followed by subsequent deacetylation. The reactivity of the 3-cyano group was demonstrated by the conversion of 4 to 2-(β-D-ribofuranosyl)indazole-3-carboxamide (5) and 2-(β-D-ribofuranosyl)indazole-3-thiocarboxamide (6). The site of ribosylation and the assignment of anomeric configuration for 4 is discussed. The magnetic anisotropy effect of the exocyclic group at C3 on the anomeric proton as determined by pmr spectroscopy is discussed.     

Tautomeric behavior of 3-(α-arylhydrazono)methyl-2-oxo-1,2-dihydroquinoxalines between hydrazone imine and diazenyl enamine forms

3-(α-Chlorophenylhydrazono-1,3,4-oxadiazol-2-ylmethyl)-2-oxo-1,2-dihydroquinoxalines 4a-d and 3-(α-chlorophenylhydrazono)methoxycarbonylmethyl-2-oxo-1,2-dihydroquinoxalines 5a-c have been clarified to exhibit the characteristic tautomeric equilibria between the hydrazone imine form C and the diazenyl enamine form D with a long-range prototropy by means of the pmr and ¹³C-nmr spectroscopies.     

The synthesis of 5-amino-v-triazolo[4,5-b] pyridin-7-one (l-deaza-8-azaguanine) and 5-amino-3-(β-D-ribofuranosyl)-v-triazolo[4,5-b] pyridin-7-one (1-deaza-8-azaguanosine)

The synthesis of l-deaza-8-azaguanine has been accomplished via a facile route from pyridine precursors. The site of rihosylation and anomeric configuration of l-deaza-8-azaguanosine and several closely related derivatives was accomplished by cmr and pmr, respectively.     

The synthesis of 2-substituted azino-3-(β-D-ribofuranosyl)-5-carboxymethylenethiazolidin-4- ones

2-(1-Isopropylidene)azino-3-β-D-ribofuranosyl-5- methoxycarbonylmethylenethiazolidin-4-one (IV) and 2-(1-methylbenzilidene)azino-3-β-D-ribofuranosyl-5-carboxymethylenethiazolidin-4-one were prepared by independent synthesis utilizing either acid catalyzed fusion of 2-(1-isopropylidene)azino-5-methoxycarbonylmethylenethiazolidin-3(H)-4-one (II) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose, silylation procedure with 2,3,5-tri-O-benzoyl-D-ribofuranosyl bromide or by cyclization of new isopropylidene and/or methylbenzilidene derivatives (VII) of 4-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)thiosemicarbazide (VI) with maleic anhydride and subsequent methylation. The synthetic approach has unambigously established the glycosilation site as well as anomeric configuration, which was additionally derived from pmr spectral data.     

Investigation of the reactions of 2-hydrazino-benzimidazoles with β-diketones: Synthesis of 2-(3,5-disubstituted- 1H-pyrazol-1-yl)benzimidazoles

Reaction of 2-hydrazinobenzimidazoles with β-diketones in neutral and acidic media revealed that 2-(3,5-disubstituted-1H-pyrazol-1-yi)benzimidazoles are formed in the former case, whereas hydrazones are obtained in acidic medium. Further the alkylation of > NH of the title compound was investigated. Characterisation of these products have been done by elemental analysis, ir, pmr, ¹⁹F nmr, ¹³C nmr and mass spectral studies.     

Free radicals in γ-irradiated poly-α-methylstyrene

Electron spin resonance (ESR) spectra were observed at ?160°C and at room temperature for γ-irradiated poly-α-methylstyrene. The spectrum observed at room temperature has been attributed to the radical species while that at ?160°C results from the same radical and superposition of the spectrum due to the radical ?H₂-C(CH₃)(C₆H₅)-. The radicals which are stable at room temperature could be used to graft vinyl acetate.     

The synthesis of 3-(β-D-ribofuranosyl)imidazo[4,5-c] pyridazines

7-Chloro-3-(β- D -2,3,5-tri-O-benzoylribofuranosyl)imidazo[4,5-c] pyridazine ( 3 ), obtained from the condensation of 7-chloro-3-trimethylsilylimidazo[4,5-c] pyridazine ( 1 ) with 2,3,5-tri-O-benzoyl- D -ribofuranosyl bromide ( 2 ), served as the percursor of 7-chloro- ( 4 ), 7-amino- ( 8 ), and 7-mercapto-3-(β- D -ribofuranosyl)imidazo[4,5-c] pyridazine ( 9 ). 3-(β- D -ribofuranosyl)imidazo[4,5-c] pyridazine ( 7 ) was obtained from 3-(β- D -2,3,5-tri-O-benzoylribofuranosyl)imidazo-[4,5-c]pyridazine ( 6 ). The site of ribosidation is based upon uv spectral comparisons with model methyl compounds. The assignment of the anomeric configuration is derived from pmr spectral data.     

The synthesis and spectroscopic properties of 3-(2′,4′-Xylyl)-1H,3H-quinazoline-2,4-diones

The synthesis of 3-(2′,4′-xylyl)-1H,3H-quinazoline-2,4-diones ( 1a, 9a-j ) has been accomplished. Their pmr and ir spectra data for all compounds are presented.     

Circular dichroism of copoly(γ-stearyl-L-glutamate–γ-methyl-L-glutamate)

Copoly(γ-stearly-L -glutamate-γ-methyl-L -glutamate)s with various compositions were synthesized by the ester exchange reaction of poly(γ-methyl-L -glutamate). Circular dichroism studies were carried out for solution and solid film as a function of the degree of stearylation and temperature. The slight and gradual temperature dependence of molecular ellipticity was observed for solution of all the copolyglutamates studied here and for the solid film of the copolyglutamate with the degree of stearylation of 16%, indicative of no reversal in the helix sense. However the remarkable change in negative molecular ellipticity with temperature was detected for the solid film of the copolyglutamate with a low degree of stearylation, e.g., 52%, whereas the drastic change in molecular ellipticity from a negative to positive value appeared for that with a higher degree of stearylation. This is discussed in terms of the reversal in the helix sense from a right- to left-handed α helix with the increase of temperature occurring at the melting temperature of the ordered side chain region.     

γ–α Solid–solid transition of isotactic polypropylene

X-ray diffraction patterns have been taken as a function of time and temperature on a sample of polypropylene held under high pressure (4.14 kbar) for 180 hr. at a temperature of 248°C. and subsequently cooled to room temperature. The molded sample initially crystallizes in the triclinic γ–phase but transforms to the γ–phase at elevated temperatures. The rate of conversion from γ to α is a function of time and temperature and tends to approach a constant value with increasing time. The nature of the thermal changes occurring in the sample was also studied by differential scanning calorimetry. It appears that at low scan speeds, there is a solid–solid transformation from the α-phase to the γ–phase, but at high scan speeds, the γ–phase melts without conversion to the α-phase.     

On the mechanism of hydrolysis of the triazolobenzodiazepine,triazolam. Spectroscopic study

The hydrolysis of 8-chloro-6-(2′-chlorophenyl)-1-methyl-4H[1,2,4]triazolo[4,3-a][1,4]benzodiazepine (Triazolam) at room temperature, involves a reversible mechanism. The intermediate is a protonated species and the final product is the ring-opened compound resulting from the reversible scission of the imine bond. The two compounds were determined simultaneously as a function of pH with pmr and cmr spectrometry. Spectral data of the benzophenone derivative II (ir, cmr, pmr) are reported.     

Die Kristallstrukturen von α- und β-K3OCl

The Crystal Structures of α- and β-K₃OCl The orange coloured compound K₃OCl has been prepared. It exists in a low temperature modification (α-K₃OCl) and a high temperature modification (β-K₃OCl). The transition temperature is 364 ± 5 K. The crystal structures were determined by x-ray diffraction. α-K₃OCl crystallizes at room temperature in the orthorhombic space group Pbnm (Z = 4) with the cell parameters a = b = 723.9(2) pm and c = 1 027.7(2) pm in the anti-GdFeO₃-structure type. The high temperature modification β-K₃OCl crystallizes (Z = 1) in the cubic space group Pm3m in the β-Ag₃SI-structure type with a = 516.2(2) pm (T = 393 K).     

Convenient preparative methods for N-aryl-γ-pyridones from γ-pyrones

2-Hydroxymethyl-5-methoxy-4-H-pyran-4-one ( 1 ) reacts with aniline and six aniline derivatives in very dilute aqueous hydrochloric acid at reflux temperature to give the N-aryl-γ-pyridone. A second procedure utilizes the aromatic amine hydrochloride by reacting it with 1 in aqueous medium at reflux temperature. p-Nitroaniline hydrochloride and 1 give the N-aryl-γ-pyridone in 65% yield, as opposed to 12% from the dilute acid procedure.     

Thermal and transport properties of copoly(γ-stearyl L-glutamate-γ-methyl L-glutamate)

Copoly(γ-stearyl L-glutamate-γ-methyl L-glutamate)s with various compositions were synthesized by ester exchange of poly(γ-methyl L-glutamate) with stearyl alcohol. The temperature dependence of the volume and helical spacing of the copolyglutamates thus prepared was examined from 0 to 100°C, observing the melting and crystallization of the long alkyl side chain attached to the polypeptide backbone. The melting temperature of the long side chain increased with increasing stearyl L-glutamate content. With increasing temperature, the α helical spacing decreased, especially with the melting of the side chain. On the other hand, the volume increased with increasing temperature and a marked increase was observed on melting. The above two phenomena were elucidated according to the structural model of the long side chain of the copolyglutamates proposed here. The transport properties, permeability coefficients were found to be considerably affected by the side-chain structure of the copolyglutamate and by the melting or crystallization of the side chain. The permeability coefficient of the copolyglutamate with 67% degree of stearylation, varied as much as two orders of magnitude before and after melting or crystallization. It was also confirmed that the permeability coefficient is controllable by the side-chain structural change of polypeptides.