Dezso Korbonits

Synthesis of 4-aminopyrimidines from 1,2,4-oxadiazoles. Part 4. A novel heterocyclic rearrangement: formation of 4-hydroximinohexahydropyrimidines from 3-(2-aminoethyl)-4,5-dihydro-1,2,4-oxadiazoles

The 4,5-dihydro derivatives of 3-(2-aminoethyl)-5-substituted-1,2,4-oxadiazoles 1 have been prepared. These derivatives 8a–d rearrange readily, but in contrast to compounds 1, not to pyrazoles, but to 2-aryl-1-benzyl-4-hydroximinohexahydropyrimidines 9a–d. Studies on the mechanism of the 1→2 azole–azole, and the novel 8→9 azole–azine, rearrangements revealed that the site of the side chain nitrogen attack is controlled by the presence or absence of a delocalized π-electron system in the starting azole ring. Compound 9a and benzaldehyde gave cis- and trans-6-benzyl-3,5-diphenyl-5,6,7,8-tetrahydro-3H-[1,2,4]-oxadiazolo[4,3-c]pyrimidines 16 and 17, respectively. The structures of 9a, 16 and 17 were confirmed by X-ray crystallography.

Ring transformation of 1-[(1,2,4-oxadiazol-3-yl)methyl]isoquinolines into 2-acylaminopyrazolo[5,1-a]isoquinolines

Selective reduction of 1-[(1,2,4-oxadiazol-3-yl)methyl]-3,4-dihydroisoquinolines (8) gives the tetrahydro derivatives (12) which readily isomerize to 2-acylaminopyrazolo[5,1-a]isoquinolines (13). Compounds (13) were also obtained by reaction of the isoquinolinylacetamide oxime (11) with esters (6). A comparision of ring transformations in the series of compounds (8) and (12) indicated that both followed the same mechanism. This provided further support to the proposed1a extension of the Type-2 Boulton–Katritzky scheme.

Chemistry of the pseudobasic amino alcohols. Part 40. Synthesis of three new condensed nitrogen heterocyclic systems

Replacement of the central oxygen atom of the heptacyclic condensed diisoquinoline 3 by reaction with hydrazine, hydroxylamine or thiourea in a simple method gave three new heterocyclic ring systems involving 1,2,4,5-tetrazine (7), 1,2,4,5-oxatriazine (8) and 1,2,4,6-tetrazepine (9) central rings.

Crystal structure of Chinoin-103 (±) -1- cyclohexylamino-4- (1 -naphthyloxy) -3 -butanol, maleate, C20H27NO2·C4H4O4

Abstract The crystal structure of Chinoin-103, a maleate salt of a new selective adrenergic β-receptor blocking agent, has been determined by X-ray diffraction analysis. Crystal data: C24H31N06, monoclinic (P21/c), a=21.307(4), b=12.307(5), c=18.524(2) A, β=102.86(1)°, Vc=4735.5 A3 Z=8. The asymmetric unit contains two crystallographically independent ion pairs with very similar geometries. The only significant conformational difference is the positioning of the cyclohexyl group with respect to the oxybutanolamine side chain. Each maleate anion, stabilized by an intramolecular hydrogen bond, is hydrogen bonded to three oxybutanolamine moieties of three different cations so as to form infinite layers parallel with the ab-plane. The layers are held together by weaker van der Waals forces. The structural model has been refined to a final linear R value of 0.083 for 5269 reflections.