ChemInform Abstract: Pyrazolo[4′,3′:5,6]pyrano[2,3‐b]quinoxalin‐4(1H)‐one: Synthesis and Characterization of a Novel Tetracyclic Ring System.

Abstract

Pyrazine derivatives R 0550Pyrazolo [4',3':5,6]pyrano[2,3-b]quinoxalin-4(1H)-one: Synthesis and Characterization of a Novel Tetracyclic Ring System. -(ELLER*, G. A.; DATTERL, B.; HOLZER, W.; J.

A SAR Study of Novel Antiproliferative Ruthenium and Osmium Complexes with Quinoxalinone Ligands in Human Cancer Cell Lines

“…Anal. (C 15 H 10 N 4 O): C, H, N. Alternatively, the compound was synthesized by reaction of ethyl 3-oxo-3,4-dihydro-quinoxaline-2-carboxylate (0.22 g, 1.0 mmol) and 1,2-phenylenediamine (0.13 g, 1.2 mmol) in ethylene glycol (4.0 mL) under argon at 170 °C for 3 h. After cooling to room temperature, the mixture was allowed to stand in a freezer (−20 °C) for 3–4 h. Then the crude product was filtered off by suction, washed with methanol (3 × 3 mL), and dried in vacuo. The purification was performed as described above using acetic acid (3.5 mL), diethyl ether (8 mL, 3 × 5 mL), 1 M aqueous orthophosphoric acid (4 mL), 1 M aqueous sodium hydroxide (4.5 mL), and water (5 × 10 mL).…”

Heterocyclic Analogues of Xanthone and Xanthione. 1H-Pyrano[2,3-c:6,5-c]dipyrazol-4(7H)-ones and Thiones: Synthesis and NMR Data

“…In the course of a program devoted to the synthesis of new heterocyclic scaffolds for bioactive compounds we recently presented the synthesis of various [5,6]pyrano[2,3- c ]pyrazol-4(1 H )-ones of type 4 , which can be considered as heterocyclic analogues of xanthone (Scheme 1) [9,10,11,12,13,14,15,16]. The synthesis of compounds 4 is based on the reaction of 2-pyrazolin-5-ones 1 with o -haloheteroarene-carbonyl chlorides 2 under the conditions described by Jensen for the C-4 acylation of pyrazolones (calcium hydroxide, dioxane, reflux) [17] and subsequent ring closure of the resulting 4-heteroaroyl-pyrazol-5-ols 3 (Scheme 1).…”

“…The synthesis of compounds 4 is based on the reaction of 2-pyrazolin-5-ones 1 with o -haloheteroarene-carbonyl chlorides 2 under the conditions described by Jensen for the C-4 acylation of pyrazolones (calcium hydroxide, dioxane, reflux) [17] and subsequent ring closure of the resulting 4-heteroaroyl-pyrazol-5-ols 3 (Scheme 1). Following this approach, we have obtained compounds of type 4 bearing – amongst others – a pyridine (all positional isomers) [9], quinoline [9], pyridazine [11], pyrimidine [11], pyrazine [15], thiophene (all positional isomers) [10,11], benzo[ b ]thiophene [10] and thieno[2,3- b ]thiophene systems [11] as the variable heteroaromatic moiety (‘Het’) condensed to the central γ-pyranone ring. …”