Alain Fruchier

Porphyrins with four azole substituents in meso positions: X-ray crystal structure of Meso-tetrakis-(1-benzylpyrazol-4-yl)-porphyrin at 200 K

Abstract Several new porphyrins have been prepared in improved yields using an established method which was adapted to formylpyrazoles bearing on the pyrazole N 1 -nitrogen protective groups. The deprotection of N-para -methoxybenzyl and SEM protected meso -pyrazolylporphyrins afforded the first known pyrazolylporphyrins with pyrazole free N H groups. The crystal and molecular structure of meso -tetrakis-1-(benzyl-pyrazol-4-yl)porphyrin 4a has been solved by X-ray analysis. The porphyrin core displays a similar pattern of bond distances and angles to that of meso -tetraphenylporphyrin itself. The pyrazole rings are almost perpendicular to the macrocyclic ring in such a way that the nitrogen lone pairs of the pyrazole N 2 atoms are situated, up, down, down, up, with regard to it (ααββ atropisomer).

The structure of N-aminoazoles: an experimental (X-ray and 15N NMR) and theoretical study

INDO calculations with complete optimization of the geometries (INDO ∥ INDO) have been carried out on the seventeen parent N-methyl and N-aminoazoles. The results are consistent with the available experimental evidence and provide a coherent picture of the conformation of the sp3 amino group. The nitrogen-15 chemical shifts of eleven N-aminoazoles have been determined for the first time. Experimental determination of the geometry by X-ray crystallography has been carried out on 1 -aminobenzimidazole: P21/n,a= 7.972 5(4), b= 11.041 1 (4), c= 7.525 1 (3)A, β= 94.435(3)°, and on 2-aminobenzotriazole: P21/c, a= 11.590 0 (5), b= 4.603 1 (8), c= 12.559 1 (8)A, β= 109.914(4)°.

13C NMR of indazoles

The carbon-13 chemical shifts and some selected coupling constants of 183 indazoles are reported. The main conclusions of the original references are briefly summarized.

THE STRUCTURE OF THE COMPOUNDS RESULTING FROM THE REACTION OF ARYLHYDRAZINES WITH DEHYDROACETIC ACID : AN NMR AND CRYSTALLOGRAPHIC STUDY

Abstract The structure of the product obtained by reacting phenylhydrazine, p-chlorophenylhydrazine and hydrazine itself with dehydroacetic acid has been established by a combined use of X-ray crystallography and NMR (1H and 13C) spectroscopy. The X-ray structure of 1-phenyl-3-methyl-4(1-phenyl-3-methyl-1H-pyrazol-5-yl)-2H-3-pyrazolin-5-one1d has been determined. The compound crystallizes in the space group P 2 1 a [C20H18N4O, a = 11.801(2), b = 7.911(1), c = 18.363(2) A, α = 90.00°, β = 100.04°, γ = 90.00°, Z = 4]. The structure corresponds to the NH-tautomer of the pyrazolinone moiety; the angle of twist corresponding to pyrazole rings, defined as C1-C2-C4-C5, is −119.1(7)°. NMR spectrum allows to estimate the tautomeric equilibrium constant in solution and in the solid state. The X-ray structure of compound 1 (NH-tautomer) was determined and compared with NMR results (solution and solid state).

A 1H and 13C nuclear magnetic resonance and X-ray diffraction study of the tautomerism of 2-hydroxy- and 2,3-dihydroxy-pyridine N-oxides. X-Ray molecular structure of 2-hydroxypyridine N-oxide

From a 1H and 13C NMR study, in dimethyl sulphoxide, of twelve 2-hydroxy-, 2,3-dihydroxy-pyridines, 2,3-dihydroxypyridine N-oxides, and their methoxy derivatives it is possible to conclude that both pyridin-2-ones and 1-hydroxypyridine-2-ones exist in solution as 2-oxo tautomers. The molecular structure of 2-hydroxypyridine N-oxide has been determined by X-ray diffraction methods; as in solution, this compound exists in the crystal state as the 1-hydroxypyridin-2-one tautomer.

NMR Studies in the Heterocyclic Series. XXIII. - 13C Spectra of Indazole and 3-Azido-Indazole in Acidified Dimethylsulfoxid Solutions

Abstract We reported previously the 13C NMR spectra of indazole 1 2 and 3-azido-indazole 2 3.

Weitreichende H,H-Kopplungskonstanten in N-methylierten Azolen

Long-range H,H-couplings in N-methylated azoles were studied.4J couplings between N-methyl and adjacent ring protons could always be observed, whereas similar5J couplings were not present. This result may be a useful tool for structure elucidation of isomeric N-methylated azoles.

STRUCTURE OF 3-AMINO-4,5-DIHYDROPYRAZOLES IN ACID MEDIA : X-RAY STRUCTURE OF 3-AMINO-1-PHENYL-4,5-DIHYDROPYRAZOL-2-IUM PICRATE AND THE ORIGIN OF BROAD SIGNALS IN 1H NMR SPECTROSCOPY

The origin of the broadening of NMR signals in 3-amino-4,5-dihydropyrazoles has been studied in the 1-phenyl series. It has been proved that the broadening is due to the presence of acid in some solvents, like deuteriochloroform, by reproducing it by addition of trifluoroacetic acid. To determine the protonation site of 3-amino-1-phenyl-4,5-dihydropyrazole 1, the crystal structure of its picrate 5 was determined. Contrary to other dihydropyrazoles, 1 protonates on N2, like an amidine.

The molecular structure of 3(5)-methyl-4,5(3)-trimethylenepyrazole hydrochloride and its13C and15N NMR spectroscopy

The title compound (C7N2H10, HC1, 1/2H2O) crystallizes in the space groupC2/c with cell parameters:a=11.651(9),b=16.309(1),c=9.167(1)Å,β=94.95(3)°,Z=8, withd=1.287 g cm−3. One of the chlorine atoms lies on a twofold axis, the second and the oxygen atom of the water molecule have disordered positions. Intermolecular interactions through hydrogen bonds are established between nitrogen atoms of the pyrazole ring and chlorine atoms or the water molecule. In this way, chains of ‘molecules’ are built; these chains, through van der Waals interactions, form layers which are stacked in the a direction. The1H,13C, and15N NMR (this last using the double labelled compound) have been recorded in solution and the13C NMR spectrum also in the solid state (CP/MAS technique). The NMR parameters (δ andJs) thus obtained are discussed using the molecular structure.

The Reaction of Heptachlor on Alumina Impregnated with Sulfuric Acid. A Ready Synthesis of 3-Exophenylchlordene

Abstract When heptachlor (la) (I-exo-3,7,8,9,10,10-heptachloro-endo-tricyclo-(5,2,1,0,2,6)-deca-4,8 diene) in benzene is treated with an alumina/sulfuric acid solid matrix up to 90% of 3-exo-phenylchlordene (1b) is obtained as the only isolable product. This easy and efficient route to substituted chlordenes suggest the possibility of incorporating photochemically degradable residues onto the heptachlor skeleton.