Convenient syntheses of pyrazolo[3,4-b]pyridin-6-ones using either microwave or ultrasound irradiation

Rodrigues-Santos, Cláudio Eduardo; Echevarrı́a, Aurea

doi:10.1016/j.tetlet.2010.11.054

Cited by 35 publications

(24 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, this result is contrary to those described by Rodrigues‐Santos et al . who claimed that isomers 2 are always obtained.…”

Section: Resultscontrasting

confidence: 99%

“…First, we decided to reproduce the experimental conditions used by Rodrigues‐Santos et al . using pyridone 1 a and phenylhydrazine 4 (R 3 = Ph).…”

Section: Resultsmentioning

confidence: 99%

“…A literature search revealed that there is not a single example of such kind of structures, and only a work by Rodrigues‐Santos et al . published in 2011 in which they claimed that the reaction with phenylhydrazine 4 (R 3 = Ph) (or substituted phenylhydrazines) only affords isomer 2 …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An Unequivocal Synthesis of 2‐Aryl Substituted 3‐Amino‐2,4,5,7‐tetrahydro‐6H‐pyrazolo[3,4‐b]pyridin‐6‐ones

et al. 2017

View full text Add to dashboard Cite

The reaction between pyridones (1) and substituted hydrazines 4 can afford two different regioisomeric pyrazolo[3,4‐b]pyridin‐6‐ones 2 and 3 depending on the initial substitution of the methoxy group and the direction of the cyclization. In the case of phenylhydrazine 4 (R3 = Ph), we have clearly shown that the treatment of pyridones 1a–d with 4 (R3 = Ph) in MeOH at temperatures below 140°C yields, independently of the nature and position of the substituents present in the pyridone ring, the open intermediates 7a–d. When the reaction is carried at 140°C under microwave irradiation, the corresponding 2‐aryl substituted pyrazolo[3,4‐b]pyridines 3a–d are always formed. We have experimentally determined, using DSC techniques, the activation energies of the two steps involved in the formation of 3: a) substitution of the methoxy group present in pyridones 1 with phenylhydrazine 4 (R3 = Ph) to afford intermediates 7 and b) cyclization of intermediates 7 to yield pyrazolopyridines 3. The results obtained, 15 and 42 kcal⋅mol−1 respectively, are in agreement with the experimental findings.

show abstract

“…However, this result is contrary to those described by Rodrigues‐Santos et al . who claimed that isomers 2 are always obtained.…”

Section: Resultscontrasting

confidence: 99%

“…First, we decided to reproduce the experimental conditions used by Rodrigues‐Santos et al . using pyridone 1 a and phenylhydrazine 4 (R 3 = Ph).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

An Unequivocal Synthesis of 2‐Aryl Substituted 3‐Amino‐2,4,5,7‐tetrahydro‐6H‐pyrazolo[3,4‐b]pyridin‐6‐ones

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Thus, these compounds have potential in the treatment of bipolar disorder, diabetes, dementia, Alzheimer's disease, schizophrenia, depression, and cancer [110]. Rodrigues-Santos et al [111] have reported the synthesis of pyrazolo [3,4-b]pyridin-6-ones 270 (12 examples) both by the conventional method and by MW irradiation (Scheme 74). 270 were obtained in moderate to good yields (50-85%) using the conventional methanol reflux method in 4-24 h. Using this MW method, 270 were produced in moderate yield (50-65%), which is low compared to the conventional methodology, but is 12-96 times faster than conventional method.…”

Section: Miscellaneousmentioning

confidence: 99%

Microwave-assisted synthesis of nitrogen-containing heterocycles

Majumder

Gupta

Jain

2013

Green Chemistry Letters and Reviews

104

View full text Add to dashboard Cite

“…This effect induces very high local pressure and temperatures inside the bubbles and enhances mass transfer and turbulent flow in the liquid [25]. Ultrasound has been utilized to accelerate a number of synthetically useful reactions, especially in heterocyclic chemistry [26-36]. …”

Section: Introductionmentioning

confidence: 99%

Ultrasonic irradiation assisted efficient regioselective synthesis of CF3-containing pyrazoles catalyzed by Cu(OTf)2/Et3N

Al‐Bogami

Saleh

Albishri

2013

Chemistry Central Journal

View full text Add to dashboard Cite

BackgroundMost of the known approaches to the synthesis of CF3-containing organic compounds suffer from serious drawbacks. For example the starting materials required for these methods are rather difficult to obtain, or they are fairly toxic and inconvenient to work with and methods for direct fluorination and trifluoromethylation do not always allow the introduction of the CF3-group at the required position of a molecule.ResultsAn efficient and attractive regioselective synthesis of a series of novel pyrazoles containing the trifluromethyl moiety was achieved using Cu(OTf)2/Et3N as an efficient catalytic system under ultrasonic irradiation.ConclusionsCu(OTf)2/Et3N catalyst showed a great advantage over all the investigated catalysts, and the ultrasonic irradiation method offered high yields of pyrazoles in short reaction time compared with classical conditions. gHMBC spectra of the product were used to rationalize the observed regioselectivity.

show abstract

Convenient syntheses of pyrazolo[3,4-b]pyridin-6-ones using either microwave or ultrasound irradiation

Cited by 35 publications

References 11 publications

An Unequivocal Synthesis of 2‐Aryl Substituted 3‐Amino‐2,4,5,7‐tetrahydro‐6H‐pyrazolo[3,4‐b]pyridin‐6‐ones

An Unequivocal Synthesis of 2‐Aryl Substituted 3‐Amino‐2,4,5,7‐tetrahydro‐6H‐pyrazolo[3,4‐b]pyridin‐6‐ones

Microwave-assisted synthesis of nitrogen-containing heterocycles

Ultrasonic irradiation assisted efficient regioselective synthesis of CF3-containing pyrazoles catalyzed by Cu(OTf)2/Et3N

Contact Info

Product

Resources

About