Synthesis of novel 7-alkynylindazole derivatives: molecular and crystal structure of 7-(pent-1-ynyl)-1H-indazole (original) (raw)
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Efficient Synthesis of 7-Substituted or 3,7-Disubstituted 1H-Indazoles
Synlett, 2007
This work reports on the synthesis of the novel indazole scaffolds 7-OTf-1H-indazole (trifluoromethanesulfonic acid 1Hindazol-7-yl ester), 7-iodo-1H-indazole and 3-bromo-7-iodo-1Hindazole. These new compounds are potent building blocks in divergent syntheses of indazoles via palladium cross-coupling reactions.
Efficient Synthesis of 7-Substituted or 3,7-Disubstituted 1 H -Indazoles
Synlett, 2007
Abstract: This work reports on the synthesis of the novel indazole scaffolds 7-OTf-1H-indazole (trifluoromethanesulfonic acid 1Hindazol-7-yl ester), 7-iodo-1H-indazole and 3-bromo-7-iodo-1Hindazole. These new compounds are potent building blocks in divergent syntheses of indazoles via palladium cross-coupling reactions.
Arkivoc, 2014
A one-pot Sonogashira coupling-heteroannulation of 4-iodo-1-phenylsulfonyl-5-trifluoroacetamidoindazole with terminal acetylenes using bis(triphenylphosphine)palladium(II) dichloride as the catalyst, cuprous iodide as the co-catalyst and triethylamine as the base in DMF furnished, after N(3)-deprotection, 7-H/substituted 3,6-dihydropyrrolo[3,2-e]indazoles in high yields. This is the first general synthesis of pyrrolo[3,2-e]indazoles. Uncatalyzed hydrodesilylation was observed during reaction with trimethylsilylacetylene, leading to the 7unsubstituted parent pyrrolo[3,2-e]indazole.
A Versatile Synthesis of Substituted Indazoles
HETEROCYCLES, 1995
A four-step synthetic sequence for substituted indazoles was presented from 2-acylcyclohexane-1.3-diones via either simultaneous or stepwise dehydration and dehydrogenation of 4-substituted 4-hydroxy-4.5.6.7tetrahydroindazoles as a key step. The synthetic methods for indazole nucleus are somewhat limited to involve condensation of hydrazino group,' generated by in situ reduction of diazo group in c-diazophenyl ketones, with C-0 of the substi tuent at the neighboring posi tion, and dehydrogenation of 4.5,6,7-tetrahydroindazoles. The former method, however, is suffering from low yields, limitations of employable diazophenyl ketone^,^ explosive intermediates.' and the latter method is also suffering from extreme reaction conditions5 as well as low yields.' Other methods have been reported, but so far not so effective to overcome the limitations of introducing substituent on indazole skeletons, especially at C3 and/or ~4 .~ In the present paper, we describe a facile and efficient route for the preparation of indazoles, in which substituents can be easily introduced at C3 andlor Ca. RESULTS AND DISCUSSION Our strategy stems from the idea that the introduction of a proper leaving group on the tetrahydroindazole system may affect the dehydrogenation step. Upon this rationale, 4-hydroxy-4.5,6.7-tetrahydroindazoles were selected as key intermediates, which may readily undergo either stepwise or simultaneous dehydration and dehydrogenation. The synthetic sequence is, thus, quite straightforward as shown in Scheme I. The prerequisite 2-acylcyclohexane-1.3-diones (1) were prepared by previously reported methods either direct acylation7 of cyclohexane-1.3-dione or via Fries rearrangements of 3-acylow-2-cyclohexenones9 in 88.92% yields. The latter procedure gave better yields, 8 as reported. It is worthy to note that I3c nmr spectral data provided information for the enol-keto tautomerism on 2-acylcyclohexane-1.3-diones. The presence of one sp2 carbon resonance (6 112.0) and three carbonyl resonances at 6 194.9. 199.0, and 210.3 implies that keto form is the major component in compound (la) on the "C nmr scale. In the system with aromatic ring, compound (lb), however, four 2 additional sp carbon resonances appeared at 6 127.5. 128.1. 131.9. 134.2 with disappearance of the two sp3 carbon resonances at 6 32.1. and 37.9, representing G and Cs, respectively. and one carbonyl resonance was shown at 6 198.7. This impies that enol form is the major component in compound (Ib). On
Synthesis of Novel Substituted Indazoles via Nucleophilic Substitution of Hydrogen
New four-substituted indazoles 4a-e were synthesized by regioselective nucleophilic substitution of hydrogen of N-alkyl-7-nitroindazoles 2a,b with arylacetonitriles 3a-c. Compounds 4a-e were reacted with arylsulfonyl chloride in pyridine to give some new indazole linked sulfonamides with good yields. The S N H at position C-4 of 7-nitroindazole with arylacetonitrile is confirmed by X-ray diffraction analysis of compounds 4e and 6a. C 2015 Wiley Periodicals, Inc. Heteroatom Chem. 26:374-381, 2015; View this article online at wileyonlinelibrary.com.
Synthesis of indazole motifs and their medicinal importance: An overview
European Journal of Medicinal Chemistry, 2015
Indazoles is an important class of heterocyclic compounds having a wide range of biological and pharmaceutical applications. There is enormous potential in the synthesis of novel heterocyclic systems to be used as building blocks for the next generation of pharmaceuticals as anti-bacterial, anti-depressant and anti-inflammatory. Fused aromatic 1H and 2H-indazoles are well recognized for anti-hypertensive and anti-cancer properties. The present review focuses on novel routes of their synthesis and various biological activities.
Tetrahedron, 1999
This paper describes a Suzuki Type cross coupling reaction of 3iodoindazoles with aryl and heteroaryl boronic acids as a general route to 3arylindazoles. The coupling reaction is illustrated by the preparation of new aryl-or heteroarylindazoles 7. Scope and limitation of the method are outlined. The coupling reaction works best on a 1-substituted indazole nucleus. The usefulness of the reaction is illustrated by a short practical synthesis of YC-1, a pharmacological agent potentialy useful for the treatment of cardiovascular diseases or erectile dysfunction.
Synthesis, Antiprotozoal Activity, and Cheminformatic Analysis of 2-Phenyl-2H-Indazole Derivatives
Molecules, 2021
Indazole is an important scaffold in medicinal chemistry. At present, the progress on synthetic methodologies has allowed the preparation of several new indazole derivatives with interesting pharmacological properties. Particularly, the antiprotozoal activity of indazole derivatives have been recently reported. Herein, a series of 22 indazole derivatives was synthesized and studied as antiprotozoals. The 2-phenyl-2H-indazole scaffold was accessed by a one-pot procedure, which includes a combination of ultrasound synthesis under neat conditions as well as Cadogan’s cyclization. Moreover, some compounds were derivatized to have an appropriate set to provide structure-activity relationships (SAR) information. Whereas the antiprotozoal activity of six of these compounds against E. histolytica, G. intestinalis, and T. vaginalis had been previously reported, the activity of the additional 16 compounds was evaluated against these same protozoa. The biological assays revealed structural fea...