Soluble Polymer-Supported Synthesis of Pyrazoles via 1,3-Dipolar Cycloaddition Strategy

Rapid parallel liquid-phase synthesis of pyrazoles has first been developed. The 1,3-dipolar cycloaddition between nitrilimines generated in situ and soluble polymer-supported alkynyl or alkenyl dipolarophiles in parallel one-pot fashion gave the corresponding PEG-supported regioisomeric pyrazoles or regiospecific pyrazolines. The latter was assuredly oxidated by DDQ to PEG-supported regiospecific pyrazoles. Cleavage from the support under mild conditions afforded pyrazoles in good yields and high ouritv.     

Multicomponent Reaction for Synthesis of N-Arylsulfonyl Pyrazoles

A synthesis of functionalized N-arylsulfonyl pyrazoles from the multicomponent reaction of arylsulfonyl hydrazones and dialkyl acetylenedicarboxylates in the presence nucleophilic compounds such as pyridine, isoquinoline, or triphenylphosphine, in good yields, is described.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]     

Synthesis of β-Aminoethyl-substituted Pyrazoles

Methods have been developed for the synthesis of 3,5-dimethyl-4-(2-N-mono- and -disubstituted and also unsubstituted aminoethyl)pyrazoles from 1,1-diacetylcyclopropane.     

The Synthesis of Distamycin Analog Containing Phosphonyl Group

In order to obtain high biological activity compound, a series of distamycin analog containing phosphonyl group were synthesized by chloroform reaction and coupling reaction using DCC/HOBT as promoting additives.     

Synthesis and Antimicrobial Activity of a New Class of Benzazolyl Pyrazoles

A new class of benzazolyl pyrazoles were prepared from the simple substrates benzoxazol‐2‐thiol, benzothiazol‐2‐thiol, 1H‐benzimidazol‐2‐thiol and cinnamoyl chloride and tested for antimicrobial activity. The compounds 2‐(benzothiazol‐2‐ylthio)‐1‐(3‐(benzothiazol‐2‐ylthio)‐5‐phenyl‐1H‐pyrazol‐1‐yl)ethanone and 2‐(benzothiazol‐2‐ylamino)‐1‐(3‐(benzothiazol‐2‐ylthio)‐5‐phenyl‐1H‐pyrazol‐1‐yl)ethanone showed pronounced antibacterial activity against Klebsiella pneumoniae whereas 2‐(1H‐benzimidazol‐2‐ylthio)‐1‐(3‐(1H‐benzimidazol‐2‐ylthio)‐5‐phenyl‐1H‐pyrazol‐1‐yl)ethanone and 2‐(1H‐benzimidazol‐2‐ylamino)‐1‐(3‐(1H‐benzimidazol‐2‐ylthio)‐5‐phenyl‐1H‐pyrazol‐1‐yl) ethanone displayed excellent antifungal activity against Penicillium  chrysogenum.      

A Novel Tandem Reaction for the Synthesis of Fused Pyrazoles

Some of the fused heterocyclic compounds are important pharmaceuticals and agrochemicals. Study on their synthetic methodology is also very important in heterocyclic chemistry. The synthesises of 1H-pyrazole[5,1-b]thiazole^[1-2] and lH-thieno[2,3-c]pyrazole^[3-5] were reported by fewer literatures.     

Regioselective Synthesis of 1,3,5-Trisubstituted Pyrazoles

Abstract

A new and a simple approach toward synthesis of 1,3,5-trisubstituted pyrazoles from chalcone arylhydrazones via oxidative cyclization has been achieved. 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone was successfully used as an oxidizing agent to give excellent yields of pyrazoles.     

新型含磷拟除虫菊酯的合成及生物活性

α-羟基烃基膦酸酯;新型含磷拟除虫菊酯的合成及生物活性     

多取代吡唑合成最新研究进展

吡唑是一类重要的五元含氮杂环化合物,广泛存在于许多天然产物、生物活性分子和药物分子中,而且是一类重要的有机合成中间体.因此,近年来吡唑及其衍生物的合成引起了科学家们的极大兴趣,并得以迅速发展.对近年来多取代吡唑的合成新方法进行了综述,以期对相关领域的研究起到一定的辅助与推动作用.     

Synthesis and Anticancer Activity of Some New Fused Pyrazoles and Their Glycoside Derivatives

4‐(4‐Chlorobenzylidene)‐2,5‐diphenyl‐2,3‐dihydro‐3H‐pyrazol‐3‐one 3a and 4‐(3,4‐dimethoxybenzylidene)‐5‐phenyl‐2,3‐dihydro‐3H‐pyrazol‐3‐one 3b were prepared and were reacted with phenylhydrazine, thiosemicarbazide, hydroxylamine hydrochloride, ethyl acetoacetate, diethylmalonate, malononitrile, ethyl cyanoacetate, and thiourea yielding fused pyrazole derivatives. Some of the new compounds were reacted with cyclic and acyclic sugars to produce new S‐, O‐, and N‐glycoside derivatives. The antitumor activity against the human breast cancer cells (MCF‐7) was assessed. Four of the new compounds showed IC₅₀ values less than those of the positive control, indicating that these four compounds are better anticancer agents than doxorubicin.     

Synthesis and Antioxidant Activity of Some New Binary Pyrazoles Containing Core Phenothiazine Moiety

α,β‐Unsaturated ketones containing phenothiazine moiety 4 , 5 , and 7 were synthesized by condensation of 2‐acetylphenothiazine ( 1 ) with different aryl aldehydes 2 , 3 and dimethylformamide dimethylaceal. Pyrazoles 11 , 18 , 20 , 22 , 23 , 24 , 25 , 26 , 28 , 29 , 31 , 32 and oxazole 34 skeletons were also synthesized by 1,3‐dipolar cycloaddition reactions of α,β‐unsaturated ketones with different nucleophilic reagents. Formylpyrazole derivative 36 was synthesized through Vilsmeier–Haack reaction of phenylhydrazone 35b . Newly synthesized compounds were screened for antioxidant activity. The data showed clearly that most of the compounds anchored to phenothiazine moiety displayed good antioxidant activity using ABTS method. Furthermore, compounds 11 , 14 , and 28 exhibited high protection against DNA damage induced by the bleomycin iron complex.     

Alkynes and Nitrogen Compounds: Useful Substrates for the Synthesis of Pyrazoles

The easy preparation and functionalization of pyrazoles associated with their innumerable biological properties have made this class of N-heterocycles very attractive for the development of new synthetic routes and applications. The cyclization reactions of alkynes and nitrogen compounds represent a powerful tool for the preparation of pyrazoles. This Review covers the recent advances in the preparation of pyrazoles by reacting alkynes and nitrogen compounds under transition-metal-catalyzed or metal-free conditions.     

A Facile Method for the Synthesis of Aroyl Pyrazoles from Functionalized Ketene Dithioacetals

On treating with ammonium acetate in DMSO aroyl formyl ketene dithioacetals were transformed into valuable intermediates 3‐amino‐2‐aroyl‐3‐(methylsulfanyl)‐2‐propenals, which could be explored for the synthesis of aroyl aminopyrazoles.     

Green Approach for the Synthesis of a New Class of Diamidomethane‐linked Benzazolyl Pyrazoles and Evaluation as Antifungals

A new class of diamidomethane‐linked benzoxazolyl pyrazoles, benzothiazolyl pyrazoles, and benzimidazolyl pyrazoles were synthesized from the synthetic intermediates N‐benzazolylcarbamoylmethylcinnamides adopting environmentally benign methods. In fact, nitrile imine was generated from araldehyde phenylhydrazone in the presence of iodosobenzene and cetyltrimethylammonium bromide followed by oxidation with iodine in dimethylsulfoxide. The structures of compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectra. The title compounds were also evaluated for their antifungal activity. Amongst all the tested compounds benzimidazolyl pyrazolyl carboxamides ( 13a and 13b ) were found to be potential antifungal agents.     

Synthesis and Antimicrobial Activity of Some New 3,4‐Disubstituted Pyrroles and Pyrazoles

A variety of 3,4‐disubstituted pyrroles and pyrazoles were synthesized by the treatment of 1,3‐dipolar reagents viz., tosylmethyl isocyanide, and diazomethane to heteroaryl chalcones and evaluated for their antimicrobial activity. Among all the tested compounds, 14b and 15b displayed promising antimicrobial activity when compared with the standards particularly against Bacillus subtilis and Aspergillus niger.     

Synthesis of New Pyrazoles via Cycloaddition Reactions of Nitrilimines with 2‐Cyclopentenone Derivatives

Compounds 1,3,6,6a‐tetraphenyl‐1,6a‐dihydrocyclopenta[c]pyrazol‐4(3aH)‐ones ( 3 ), 1,3,3a,4‐tetraphenyl‐1,3a‐dihydrocyclopenta[c]pyrazol‐6‐ols ( 4 ) and 6‐hydroxy‐1,3,6,6a‐tetraphenyl‐1,5,6,6a‐tetrahydrocyclopenta[c]pyrazole‐4(aH)‐one ( 5 ) were synthesized by reaction of 3,4‐diphenyl‐4‐hydroxy‐2‐cyclopentenone ( 2a ) with nitrilimines, generated in situ by the action of triethylamine on the corresponding hydrazonyl chlorides 1 .     

Organocatalytic Enantioselective Synthesis of Pyrazoles Bearing a Quaternary Stereocenter

An efficient one‐pot asymmetric synthesis of pyrazoles bearing a chiral quaternary stereocenter has been developed. Quinine‐derived thiourea catalyzed the enantioselective addition of pyrazolones to isatin‐derived ketimines, providing the corresponding acetylated pyrazoles after in situ treatment with Ac₂O/Et₃N. The corresponding pyrazoles were afforded in high yields and excellent enantioselectivities.