Tri- and Tetracyclic Heteroaromatic Systems: Synthesis of Novel Benzo-, Benzothieno- and Thieno-Fused Pyrano[2,3-c]pyrazol-4(1H)-ones

Hölzer, W.; Eller, Gernot A.; Haring, Andreas W.; Datterl, Barbara; Zwettler, Maryam

doi:10.3987/com-06-10908

Cited by 24 publications

(2 citation statements)

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“…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).…”

Section: Introductionmentioning

confidence: 99%

“…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. …”

Section: Introductionmentioning

confidence: 99%

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

et al. 2010

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The synthesis of the title compounds is described. Reaction of 1-substituted 2-pyrazolin-5-ones with 5-chloro-1-phenyl-1H-pyrazole-4-carbonyl chloride or 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbonyl chloride, respectively, using calcium hydroxide in refluxing 1,4-dioxane gave the corresponding 4-heteroaroylpyrazol-5-ols, which were cyclized into 1H-pyrano[2,3-c:6,5-c]dipyrazol-4(7H)-ones by treatment with K2CO3/DMF. The latter were converted into the corresponding thiones upon reaction with Lawesson’s reagent. Detailed NMR spectroscopic investigations (1H, 13C, 15N) of the ring systems and their precursors are presented.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2010

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Tri‐ and Tetracyclic Heteroaromatic Systems: Synthesis of Novel Benzo‐, Benzothieno‐ and Thienofused Pyrano[2,3‐c]pyrazol‐4(1H)‐ones.

Eller¹,

Haring²,

Datterl³

et al. 2007

ChemInform

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Benzothieno-and Thienofused Pyrano[2,3-c]pyrazol-4(1H)-ones. -Pyrazolinones (I)are acylated with the appropriate carboxylic acid chlorides (IIa), (IId), and (V) in the presence of an excess calcium hydroxide to give the desired haloarylpyrazolols (III) and (VI), resp. The two-step method is completed by a subsequent cyclization reaction, an intramolecular nucleophilic substitution of the aryl halogenide. Unsubstituted title compounds like (VIII) are easily obtained by treatment of the N1-Pmb-protected congeners of type (VIIb) with trifluoroacetic acid. -(ELLER*, G. A.; HARING, A. W.; DATTERL, B.; ZWETTLER, M.; HOLZER, W.; Heterocycles 71 (2007) 1, 87-104; Dep. Drug Synth., Univ. Wien, A-1090 Wien, Austria; Eng.) -H. Hoennerscheid

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

Eller

Hölzer

2017

Journal of Heterocyclic Chem

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The synthesis of various 4-acylpyrazolones bearing in the acyl moiety either a terminal chloro-substituent or a terminal ortho-chlorophenyl group was achieved by reaction of 3-methyl-1-phenyl-2-pyrazolin-5-one (tautomer to 3-methyl-1-phenyl-1H-pyrazol-5-ol) with the corresponding acid chloride using calcium hydroxide / 1,4-dioxane. In one case (reaction with chlorobutanoyl chloride) a spontaneous cyclization occurred leading to the corresponding oxepino [2,3-c]pyrazole. Detailed NMR spectroscopic investigations with all prepared compounds were performed.

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Tri- and Tetracyclic Heteroaromatic Systems: Synthesis of Novel Benzo-, Benzothieno- and Thieno-Fused Pyrano[2,3-c]pyrazol-4(1H)-ones

Cited by 24 publications

References 22 publications

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

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

Tri‐ and Tetracyclic Heteroaromatic Systems: Synthesis of Novel Benzo‐, Benzothieno‐ and Thienofused Pyrano[2,3‐c]pyrazol‐4(1H)‐ones.

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

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