Synthesis of novel polycyclic ring systems containing two pyrano[2,3-c]pyrazol-4-(1H)one moieties

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).…”

Synthesis and NMR‐Spectroscopic Investigations with 4‐Chloroacyl‐1‐phenylpyrazolin‐5‐ones

“…Depending on the nature of the acid chloride, the obtained 4‐acylpyrazolones were transformed into a huge number of hitherto unknown fused pyrazole ring systems . One simple and smart synthetic strategy is based on the use of ortho ‐halogenated aromatic carboxylic acid chlorides in the acylation reaction to finally achieve the correspondingly fused pyrano[2,3‐ c ]pyrazolones.…”

Novel fluoro-substituted benzo- and benzothieno fused pyrano[2,3-c]pyrazol-4(1H)-ones

“…1) [5][6][7][8][9][10][11]-the latter representing the core of several biologically active molecules [12]. In compounds A one benzene system of the parent xanthone is replaced by a pyrazole system whereas ring H is a heteroaromatic moiety or a benzene ring.…”