Pyrazolidine-3,5-dione angiotensin-II receptor antagonists

The crystal structures of three angiotensin-II receptor antagonists involving different spacer groups (CO, CONH and NHCO) between the aryl rings are presented, namely 2-{4-[(3-butyl-1,4-dioxo-2,3-di­aza­spiro­[4.4]­non-2-yl)­methyl]­benzoyl}benzoic acid, C₂₆H₂₈N₂O₅, (I), 2-{4-[(3-butyl-1,4-dioxo-2,3-di­aza­spiro­[4.4]­non-2-yl)­methyl]­benz­amido}benzoic acid, C₂₆H₂₉N₃O₅, (II), and 2-{4-[(3-butyl-1,4-dioxo-2,3-di­azaspiro­[4.4]­non-2-yl)­methyl]­anilino­carbonyl}benzoic acid monohydrate, C₂₆H₂₉N₃O₅·H₂O, (III). The aryl rings of (II) are almost coplanar, in contrast with compounds (I) and (III). The conformation of (II) is induced by an intramolecular N—H⋯O hydrogen bond between the amide and carboxyl­ic acid groups.     

Electron upconversion in reactions of 1,2,4-triazoline-3,5-dione

Russian Chemical Bulletin - During the electroreduction of 4-phenyl-1,2,4-triazoline-3,5-dione under aprotic conditions, a chain reaction of its transformation to...     

A vinylsilane route to trans-7a-methylhydrind-4-en-1,6-dione

A stereoselective synthesis of the title compound is described. The overall yield is 34% starting with 2-methyl-2-cyclopentenone. The trans ring-fusion stereochemistry is established by a conjugate addition/trapping sequence.     

Synthetic and structural studies on 1,2,4-dithiazolidine-3,5-dione derivatives

Methods have been developed for the N-alkylation of 1,2,4-dithiazolidine-3,5-dione 2 and the subsequent conversion of the N-alkylated derivatives into isocyanates 5. An extension of this methodology onto a solid-support is also reported. X-ray crystallographic analysis has been carried out on potassium 1,2,4-dithiazolidine-3,5-dione 3 for structural comparison with the parent heterocycle 2.     

Regioselective bromination and iodination of aromatic substrates promoted by trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane

Selective and efficient bromination and iodination of aromatic compounds by ammonium bromide and ammonium iodide, respectively, under promotion of trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane have been explored. Mild reaction conditions, high selectivity and yield, and high reaction rate are some of the major advantages of this synthetic method.