Vincenzo Sprio

Kauranoid dieterpenes in Espeletia grandiflora

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.

Cardopatine and isocardopatine, two novel cyclobutane substances from Cardopatium corymbosum

Abstract 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.

Modifications and extensions of the Pschorr reaction in pyrazole series. Access to the [2]benzopyrano[4,3-c]pyrazole system of pharmaceutical interest

The Pschorr reaction performed under non-classical reaction conditions on the diazonium chloride derived from 2-amino-N-methyl-N-(3-methyl-1-phenyl-1H-pyrazol-5-yl)benzamide 1 afforded the epimers (3′R,4′S)- and (3′R,4′R)-4′-chloro-2′,4′-dihydro-2,5′-dimethyl-2′-phenylspiro[isoindoline1,3′-3′H-pyrazol]-3-one 4a and 4b together with the related enantiomers. The epimers were easily converted under acid conditions into both 4-chloro-3-methyl-5-[2-(methylcarbamoyl)phenyl]-1-phenyl-1H-pyrazole 5 and the potentially pharmacologically active 3-methyl-1-phenyl-1H-[2]benzopyrano[4,3-c]pyrazol-5-one 3, whereas under base conditions, as well as thermally, only compound 5 was obtained.The molecular structure of epimer 4a and that of the derivative 5 were confirmed by single-crystal X-ray analysis. The crystal of compound 5 is characterized by the presence of two conformational isomers in the unit cell.

Synthesis, molecular, and crystal structure of a new, unexpected polycyclic system: 5,12:10,12-dimethano-12H-pyrazolo[3,4-b]pyrazolo[4′,3′:6,7]azapino[2,3-f]azocine

By reacting 1-phenyl-3-R-5-methylaminopyrazoles (1a, b) and hexane-2,5-dione (2) in acetic acid compounds (4a, b), containing the title system, were obtained. They were characterized by elemental analysis, n.m.r. spectroscopy and, for (4a), X-ray crystallography of a single crystal. The structure is characterized by a fused hexacyclic system which includes two N-phenyl-substituted pyrazole rings adjacent to two azepine ones in the half-chair conformation and, finally, two five-membered fused rings.

Oxidative reactions of polyarylpyrroles. Part 3. Oxidative trimerization of 2,5-diphenylpyrrole

As in the oxidative reaction of 2,3,5-triphenylpyrrole previously studied, the oxidation of 2,5-diphenylpyrrole with potassium dichromate gave the dimer 2,2′,5,5′-tetraphenyl-3,3′-bipyrrole (2) and the related hydroxy-derivative 3-(2,5-diphenylpyrrol-3-yl)-2,5-diphenyl-2H-pyrrol-2-ol (6), together with the tetracyclic compound 1,6a-dihydro-2,5,6a-triphenylbenzo[g]pyrrolo[3.2-e]indole (3), whose formation involves the α-position of the pyrrole nucleus and the α′-phenyl group of the other pyrrole ring. In addition, large amounts of both the trimer 2,3-bis-(2,5-diphenylpyrrol-3-yl)-2,5-diphenyl-2H-pyrrole (4) and the tetracyclic compound 6a,6b-dihydro-1,3,5,6a,6b,8-hexaphenyl-2H-benzo[1,2-c:4,3-b′:5,6-b″]tripyrrole (5) were obtained. The formation of the various products of the oxidation is demonstrated in terms of the intermediate (2).