0000000000000802
AUTHOR
Vincenzo Sprio
showing 14 related works from this author
Studies on the synthesis of heterocyclic compounds. III. Preparation of some pyrazolo[3,4-C] [1,5]benzodiazocin-10(11H)one derivatives
1979
Starting from the readly available N-melhyl-N-(1-phenyl-3-R-pyrazol-5-yl)-2-nitrobenzamides (1a,b), the pyrazoles, 4-aeetyl substituted 2a,b, were prepared in high yield. Reduction of 2a gave the amino derivative 4a, which was eyclized to the desired pyrazolo[3,4-c][1,5]benzodiazo-cin-10(11H)one (5a). Compound 2b afforded 5b directly. Compound 5b was also prepared by the action of phosphorus oxychloride on N-methyl-N-(1,3-diphenylpyrazol-5-yl)-2-acetamido-benzamide (6b).
Cardopatine and isocardopatine, two novel cyclobutane substances from Cardopatium corymbosum
1978
Two new natural substances containing a cyclobutane unit, cardopatine and isocardopatine, the trans and cis isomers respectively of 5,5″ (cyclobut-1,2-ylene-diethynylene)bis 2,2′-bithiophene), together with the known α-terthienyl and 5-(but-3-en-1-ynyl)-2,2′-bithienyl, have been isolated from the roots of Cardopatium corymbosum. Evidence is given that the novel cyclobutane substances are not the products of a spontaneous dimerization of a bithienyl monomeric unit. Structure determination and conformational analysis are reported.
Synthesis of a new bridgehead nitrogen heterocyclic system. Pyrrolo [2,1-f]-1,2,4-triazine derivatives
1979
1-Ureidopyrroles of type 6a,b prepared by the general method previously described (2), readily cyclized under basic conditions giving pyrrolo [2,1-f]-1,2,4-triazine-2,4(1H, 3H)dione derivatives.
Studies in organic mass spectrometry.VIII. The electron impact mass spectra of 2,4-substituted-3-diazo-5-phenylpyrroles
1990
The electron impact mass spectra (75 eV) of the β-diazopyrroles always show the molecular ions and undergo as the main fragmentation process the elimination of nitrogen followed by ring opening reactions leading to benzonitrile either as neutral or charged species. The peaks at 26 amu below the molecular ions, which are a general feature of these spectra, are due to the presence of the corresponding pyrroles which are formed by reductive reactions during the vaporization process of the samples.
Oxidative halogenation of substituted pyrroles with cu(II). Part I. Bromination of some 3-acetylpyrroles
1990
3-Acetylpyrroles are brominated with copper(II) bromide. The reaction afforded almost quantitatively only nuclear monobromination. Evidence for the structures of final compounds was by mass spectrometry, 1 H-nuclear magnetic resonance, ir, and elemental analysis
Oxidative halogenation of substituted pyrroles with cu(II). Part II. Bromination of some ethyl 3-pyrrolecarboxylates and corresponding acids
1990
Ethyl 3-pyrrolecarboxylates and their corresponding acids are brominated with copper(II) bromide. The reaction afforded at 0°, with high-yield nuclear monobromination.
orthoeffect on the nitrosation of the 2,3-diphenyl-5(2-methoxyphenyl)pyrrole
1990
A comparison of the behaviour on the nitrosation of the isomers 5-(2-methoxyphenyl)- (1a) 5-(3-methoxyphenyl)- (1b) and 5-(4-methoxyphenyl)2,3-diphenylpyrroles (1c) carried out in the usual way with iso-amyl nitrite in a solution of sodium ethoxide in ethanol evidences that 1a is dramatically less reactive with respect to 1b and 1c. The different reactivity was ascribed to the occurrence of a strong hydrogen bond involving pyrrole NH and the ortho-methoxy group.
Synthesis of a bridgehead nitrogen system. Imidazo[1,5-b]pyridazine derivatives
1979
3,4-Dibenzoyl-2-oxobutyrate 4-semicarbazone (6a), ethyl 2,4-dioxo-3-phenacylvalerate 3-semicarbazone (6b) and diethyl phenacyloxalectate 3-semicarbazone (6c) via acid catalysed intramolecular cyclization afforded 2-phenyl-4-R-3H-imidazo[1,5-d]pyridazine-5,7-(6H)diones (8d,e,f). Elemental analyses and spectroscopic data (ir, nmr, ms) were in good agreement with the assigned structures.
Studies on the synthesis of heterocyclic compounds. Part IX. Action ofN,N-dimethylformamide dimethylacetal on some oximino-β-dicarbonyl compounds
1982
3-Oximino-2,4-pentanedione (1) and ethyl 2-oximino-3-oxobutanoate (6) reacted with N,N-dimethylformamide dimethylacetal (DFDA) to give 1,7-bisdimethylamino-3,5-dioxo-4-methoximinohepta-1,6-diene (4) and ethyl 5-dimethylamino-2-methoximino-3-oxo-4-pentenoate (8), respectively. When compounds 4 and 8 were treated with hydrazine hydrate, they gave O-methyldipyrazol-3(5)-ylketoxime (5) and ethyl 2-methoximino-3(5)-pyrazolylethanoate (9) together with its corresponding hydrazide 10, respectively. Upon action of DFDA on 3-oximino-2,4-pentanedione (1) at -20° an explosive crystalline product was obtained. On the other hand, the reaction of 3-acetoximino-2,4-pentanedione (11) with DFDA at -20° affo…
Electrochemical oxidation of 2,4,5-triaryl-substituted pyrroles.II. Oxidative dimerization of 4,5-diphenyl-2-mesitylylpyrrole
1989
2,4,5-Triaryl-substituted pyrroles lead, upon chemical or electrochemical oxidation, to an intermediate β-β'-dimer, which, in the course of the reaction, undergoes further oxidation to a tetracyclic derivative. To improve the selectivity towards the uncyclized dimer the oxidation of a triarylpyrrole in which the ortho positions of the phenyl group in position 2 are hindered by the presence of methyl groups was attempted. The cyclization was hindered, but an α-β'-dimer was obtained as the major product. An unexspected isomeric α-β'-dimer, in which the mesitylyl group is shifted into the β position of the pyrrole ring which undergoes the oxidation, was obtained in minor amounts. Electroanalyt…
New synthesis of some 1,2,5-benzothiadiazcpinc 1,1-dioxide derivatives. I
1979
2-Nitrobenzenesulfonyl chloride reacts with ω-aminoacetophenone and 4-amino-3,5-dimethyl-isoxazole to give 3 and 7, respectively. Reduction of 3 with zinc powder and acetic acid afforded the 2,5-dihydro- and 2,3,4,5-tetrahydro-1,2,5-benzothiadiazepine I,1-dioxide derivatives (4 and 5). Catalytic hydrogenolysis of 7 and successive cyclization of the intermediate 8 gave the 3-ace-thyl-2,5-dihydro-4-methyl-1,2,5-benzothiadiazepine 1,1-dioxide (9). The structures were assigned on the basis of correct elemental data and spectroscopic evidences.
The Structure and the Stereochemistry of Atractyliretin
1986
The nor-kaurane diterpene Atractyliretin was obtained by acid hydrolysis of Atractyloside, a toxic substance isolated from ATRACTYLIS GUMMIFERA L (Compositae). On the basis of spectral (IR, (1)H-NMR, (13)C-NMR and MS) analysis and chemical degradation its structure and stereochemistry was identified as 4.
ChemInform Abstract: ortho Effect on the Nitrosation of the 2,3-Diphenyl-5-(2-methoxyphenyl)pyrrole.
1990
A comparison of the behaviour on the nitrosation of the isomers 5-(2-methoxyphenyl)- (1a) 5-(3-methoxyphenyl)- (1b) and 5-(4-methoxyphenyl)2,3-diphenylpyrroles (1c) carried out in the usual way with iso-amyl nitrite in a solution of sodium ethoxide in ethanol evidences that 1a is dramatically less reactive with respect to 1b and 1c. The different reactivity was ascribed to the occurrence of a strong hydrogen bond involving pyrrole NH and the ortho-methoxy group.
Kauranoid dieterpenes in Espeletia grandiflora
1971
Abstract The resin of Espeletia grandiflora contains (-)-kaur-16-en-19-ol, (-)-kaur-16-en-19-al (not previously isolated from natural sources), (-)-kaur-16-ene and (-)-kaur-16-en-19-oic acid.