Microwave-assisted palladium mediated efficient synthesis of pyrazolo[3,4-b]pyridines, pyrazolo[3,4-b]quinolines, pyrazolo[1,5-a]pyrimidines and pyrazolo[1,5-a]quinazolines

Shekarrao, Kommuri; Kaishap, Partha Pratim; Saddanapu, Venkateshwarlu; Addlagatta, A.; Gogoi, Sanjib; Boruah, Romesh C.

doi:10.1039/c4ra02865a

Cited by 63 publications

(31 citation statements)

References 52 publications

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“…11 These promising biological and photophysical properties have prompted the development of various methods for the synthesis of functionalized pyrazolo [1,5-a]pyrimidines. [12][13][14][15][16] The vast majority of these methods mostly involve the interaction between NH-5-aminopyrazoles with 1,3-bis-electrophilic reagents (e.g., b-dicarbonyl compounds, 12 b-enaminones, 13 bhaloenones, 14 b-ketonitriles, 15 among others 16 ). Although such methodologies are generally reliable, many of them involved harsh reaction conditions, prolonged reaction times and tedious work-up, require use of additives, and oen proceed with moderate yields.…”

Section: Introductionmentioning

confidence: 99%

Simple access toward 3-halo- and 3-nitro-pyrazolo[1,5-a]pyrimidines through a one-pot sequence

2017

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Section: Introductionmentioning

confidence: 99%

Simple access toward 3-halo- and 3-nitro-pyrazolo[1,5-a]pyrimidines through a one-pot sequence

2017

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“…Using MW irradiation and conventional TH, Shekarrao et al [60] synthesized new fused pyridines 70a-g, quinolines 71a-c, pyrimidines 72a-h, and quinazolines 73a-c, with pyrazole skeleton. Under MW irradiation, the yields are higher and the reaction times decrease substantially (from 24 h to 15 min).…”

Section: Six Membered Ring Azaheterocyclesmentioning

confidence: 99%

Microwave Assisted Reactions of Azaheterocycles Formedicinal Chemistry Applications

et al. 2020

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Microwave (MW) assisted reactions have became a powerful tool in azaheterocycles chemistry during the last decades. Five and six membered ring azaheterocycles are privileged scaffolds in modern medicinal chemistry possessing a large variety of biological activity. This review is focused on the recent relevant advances in the MW assisted reactions applied to azaheterocyclic derivatives and their medicinal chemistry applications from the last five years. The review is divided according to the main series of azaheterocycles, more precisely 5- and 6-membered ring azaheterocycles (with one, two, and more heteroatoms) and their fused analogues. In each case, the reaction pathways, the advantages of using MW, and considerations concerning biological activity of the obtained products were briefly presented.

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“…Boruah et al [ 48 – 49 ] developed an efficient method for the construction of regioisomeric 1,3,4-trisubstituted pyrazolo[3,4- b ]pyridines 32 and 34 ( Scheme 5 ). In situ cyclocondensation of β-halovinyl aldehydes 29 with 5-aminopyrazoles (R = Ph, 16 ) under Heck conditions in the presence of Pd(OAc) 2 with xantphos (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) gave 6-substituted pyrazolo[3,4- b ]pyridines 34 .…”

Section: Reviewmentioning

confidence: 99%

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

Aggarwal

Kumar

2018

Beilstein J. Org. Chem.

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The condensation of 5-aminopyrazole with various bielectrophilic moieties results in the formation of pyrazoloazines, an interesting array of fused heterocyclic systems. The development of new synthetic routes towards pyrazoloazines for their biological and medicinal exploration is an attractive area for researchers throughout the world. The present review focuses on various synthetic methods developed in the last decade for the synthesis of differently substituted pyrazoloazines by a broad range of organic reactions by means of 5-aminopyrazole as a precursor. ReviewPyrazole and its derivatives are known to exhibit significant biological and pharmacological activities such as: anticancer [1,2], anti-inflammatory [3,4], antioxidant [5], antibacterial [6][7][8], analgesic [9], antiviral [10,11], antimicrobial [12,13], antifungal [6], antiglycemic [14], antiamoebic [15] and antidepressive [16,17]. Considering the immense biological properties pyrazole is one of the most widely studied nitrogen-containing heterocyclic nuclei. Fused pyrazole derivatives are composed of the pyrazole nucleus attached to other heterocyclic moieties which enable them to exhibit improved pharmacological activities compared to the isolated fragments. These compounds are currently used in several marketed drugs like cartazolate (1), zaleplon (2), sildenafil (3), allopurinol (4), indiplon (5), etazolate (6) etc. (Figure 1). Fused pyrazole derivatives, especially pyrazoloazines have been reported to mimic purine bases, present in DNA and RNA, due to close structural resemblance.In addition to the immense biological potential related to fused pyrazoles, their synthetic potential needs to be reviewed for further improvements and extension of interests. Various efforts have been developed for the synthesis of pyrazole-based fused heterocycles. 5-Aminopyrazoles have been extensively employed as useful synthons in designing and constructing a Beilstein J. Org. Chem. 2018, 14, 203-242. 204 A number of review articles have been published by us and others highlighting the synthetic and biological aspects of 5-aminopyrazoles [26][27][28] as well as on the synthesis of fused pyrazole derivatives [25]. However, a perusal of literature reveals that the importance of 5-aminopyrazoles as synthetic precursors for fused heterocycles has not been reported till now to the best of our knowledge. Recent literature shows resurgence of interest in the chemistry and bioactivity of 5-aminopyrazole derivatives leading to improvements in several already known reactions and syntheses of various fused heterocyclic derivatives with various biological activities. Considering the synthetic importance of 5-aminopyrazoles and synthesis of fused pyrazole derivatives with the need for a more general collection, herein we report an exhaustive overview of the main developments in the last decade in the chemistry of 5-aminopyrazoles for the design and synthesis of fused pyrazoloazines.The typical reactivity of 5-aminopyrazoles 5-Aminopyrazoles are polyfunctional co...

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Microwave-assisted palladium mediated efficient synthesis of pyrazolo[3,4-b]pyridines, pyrazolo[3,4-b]quinolines, pyrazolo[1,5-a]pyrimidines and pyrazolo[1,5-a]quinazolines

Abstract: An efficient method was developed for the synthesis of pyrazole fused heterocycles via the palladium-catalyzed solvent free reaction of β-halovinyl/aryl aldehydes and 3-aminopyrazoles/5-aminopyrazoles under microwave irradiation in good yields.

Cited by 63 publications

References 52 publications

Simple access toward 3-halo- and 3-nitro-pyrazolo[1,5-a]pyrimidines through a one-pot sequence

Simple access toward 3-halo- and 3-nitro-pyrazolo[1,5-a]pyrimidines through a one-pot sequence

Microwave Assisted Reactions of Azaheterocycles Formedicinal Chemistry Applications

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

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