Eckehard Cuny

Benzologs of allopurinol: Synthesis of pyrazolo [4,3-g] and [3,4-f] quinazolinones

Abstract Convenient syntheses of pyrazolo [ 4,3- g ] quinazolin-5 (6 H ) -one (3), its xanthine oxidase metabolite 4 and the [ 3,4- f ] analog 5 have been developed, involving anellation of the pyrimidine ring onto aminoindazolcarboxylic acids 9 and 18, or attachment of the pyrazol portion onto quinazolinone 22 via intramolecular azo coupling.

Solid-state conformation of 2,6-cis-and 2,6-trans-substituted dihyropyran-3-ones☆

Abstract 2,6-Dihydropyran-3-ones carrying substituents at C-2 and C-6 in cis -arrangement invariably adopt half-chair conformations in which the ring oxygen and the carbon atom next to the carbonyl group are above and below, respectively, the plane formed by the other four carbon atoms, i.e., the 2 H o or o H 2 conformation. In the case of a trans -arrangement of 2,6-substituents, the geometry of the pyramid ring falls into the B o,6 ⇌ E o ⇌ 2 H o or inverse o,6 B ⇌ o E ⇌ o H 2 section of the conformational cycle, depending on the absolute configuration of the compound; for two of the dihydropyranones, 4B and 6 , a unique skew-boat ( SB o,6 ) conformation, fixed between the B o,6 and E o geometries, was ascertained, which previously has only been observed for pyranoid enelactones.

Molecular geometry of a pyran–dioxane–cyclohexane tricycle with linear cis–trans-fusion of rings

The synthetically prepared enantiopure title compound, (2S)-(2α,4aβ,5aβ,9aα,10aβ)-2-benzoyloxymethyl-4a-hydroxy-4a,5a,6,7,8,9,9a,10a-octahydro-2H-pyrano[2,3-b][1,4]benzodioxin-4-yl benzoate diethyl ether solvate, C 26 H 26 O 8 .C 4 H 10 O (3), crystallizing as a monoetherate, shows the pyran-dioxanecyclohexane ring junctions to be cis-trans, resembling the steric arrangement of the same three rings in the antibiotic spectinomycin and in a series of cardenolides. The ether molecule with which (3) crystallizes sits in a unique «horse-saddle» arrangement, hydrogen bonded to the axially oriented tertiary hydroxyl group