58954-05-5Relevant academic research and scientific papers
Synthesis of pyrazole anchored three-coordinated organoboranes and their application in the detection of picric acid
Das, Ritwick,Kumari, Anupa,Mukundam, Vanga,Sa, Shreenibasa,Venkatasubbaiah, Krishnan
, p. 6204 - 6212 (2021)
Three-coordinated organoboron fluorophores bearing 3,5-diphenyl pyrazoles have been synthesized. The pyrazole anchored boron fluorophores show selective fluorescence quenching response to trinitrophenol (or) picric acid (PA) and have the ability to discriminate picric acid over other analytes. We investigated nonlinear optical (NLO) properties of these three-coordinated organoboron compounds (in solutions) in the presence and absence of PA. In absence of PA, the two-photon-absorption coefficient (β) of organoboron fluorophores exhibits a variation from 2 × 10-12 cm W-1 to 4 × 10-12 cm W-1. The results also reveal that the NLO characteristics of organoboron fluorophores exhibit a discernible variation with PA addition which has correlations with quenching observed in fluorescence measurements.
TBHP/Cu(OAc)2 mediated oxidation of pyrazolines: A convenient method for the preparation of pyrazoles
Kolla, Sai Teja,Somanaboina, Ramya,Bhimapaka, China Raju
, p. 1425 - 1432 (2021/02/27)
An efficient and simple oxidative protocol has been developed for the preparation of pyrazoles from pyrazolines mediated by TBHP/Cu(OAc)2 at room temperature. The present protocol has been successfully applied for the preparation of various pyrazole compounds from heterocyclic pyrazolines.
B-N coordinated triaryl pyrazole: Effect of dimerization, and optical and NLO properties
Mukundam, Vanga,Sa, Shreenibasa,Kumari, Anupa,Das, Ritwick,Venkatasubbaiah, Krishnan
supporting information, p. 12725 - 12737 (2019/10/28)
A series of triaryl pyrazole B ← N coordinate dimers with different π-conjugated (spacer) bridges (compound 4 (no spacer); compound 7 (2,5-bis(hexyloxy)benzene); compound 8 (9,9-dihexyl-9H-fluorene); compound 9 (9-hexyl-9H-carbazole); compound 10 (thiophene); compound 11 (2,2′-bithiophene)) has been synthesized from simple triaryl pyrazoles. Three different synthetic protocols were applied to synthesize the desired B ← N coordinate pyrazole dimers. All the B ← N coordinate pyrazole dimers exhibit absorption maxima between 337 and 399 nm with good molar absorption coefficients (12 000 to 22 100 M-1 cm-1 in CH2Cl2). They are highly emissive in the solution state with quantum yields of up to 0.94. Due to a substantial change in the excited state dipole moment, B ← N coordinate pyrazole dimers exhibit versatile and appreciably large nonlinear optical (NLO) properties. The dimer symmetry and the presence of donor or acceptor moieties affect the two-photon-absorption (TPA) cross-section substantially. In addition, the investigation reveals that the dimer π-conjugation length in all dimer variants has a remarkable impact on the NLO characteristics.
Visible light mediated metal-free oxidative aromatization of 1,3,5-trisubstituted pyrazolines
Annes, Sesuraj Babiola,Rajmohan, Rajamani,Ramesh, Subburethinam,Vairaprakash, Pothiappan
supporting information, (2019/07/22)
The visible light mediated oxidation of 1,3,5-trisubstituted pyrazolines under metal-free conditions was developed. Various substituted pyrazolines were oxidized to pyrazoles by irradiation with visible light/sunlight. A plausible mechanism was proposed f
Nano-TiO2: An efficient and reusable catalyst for the synthesis of 1,3,5-substituted pyrazoles
Akbari, Ali,Mirjalili, Bibi Fatemeh
, p. 119 - 123 (2016/07/15)
(Formula presented) A Nano-TiO2 is an efficient catalysis for the synthesis of 1,3,5-substituted pyrazoles via condensation of 1,3- diketones and hydrazines. Simple procedure, mild heating, solvent free, high yielding, and easy workup are some advantages of this protocol. The catalyst can be recovered easily and reused many times without significant loss in catalytic activity and selectivity.
Radical Addition of Hydrazones by α-Bromo Ketones to Prepare 1,3,5-Trisubstituted Pyrazoles via Visible Light Catalysis
Fan, Xiu-Wei,Lei, Tao,Zhou, Chao,Meng, Qing-Yuan,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
, p. 7127 - 7133 (2016/08/30)
A novel efficient tandem reaction of hydrazones and α-bromo ketones is reported for the preparation of 1,3,5-trisubstituted pyrazoles by visible light catalysis. In this system, the monosubstituted hydrazones show wonderful reaction activity with alkyl radicals, generated from α-bromo ketones. A radical addition followed by intramolecular cyclization affords the important pyrazole skeleton in good to excellent yields. This efficient strategy under mild conditions with wide group tolerance provides a potential approach to the 1,3,5-trisubstituted pyrazoles.
Transition-Metal-Free N-Arylation of Pyrazoles with Diaryliodonium Salts
Gonda, Zsombor,Novák, Zoltán
supporting information, p. 16801 - 16806 (2015/11/16)
A new synthetic method was developed for the N-arylation of pyrazoles using diaryliodonium salts. The transformation does not require any transition-metal catalyst and provides the desired N-arylpyrazoles rapidly under mild reaction condition in the presence of aqueous ammonia solution as a mild base without the use of inert atmosphere. The chemoselectivity of unsymmetric diaryliodonium salts was also explored with large number of examples.
Copper-catalyzed aerobic C(sp2)-H functionalization for C-N bond formation: Synthesis of pyrazoles and indazoles
Li, Xianwei,He, Li,Chen, Huoji,Wu, Wanqing,Jiang, Huanfeng
, p. 3636 - 3646 (2013/06/04)
A simple, practical, and highly efficient synthesis of pyrazoles and indazoles via copper-catalyzed direct aerobic oxidative C(sp2)-H amination has been reported herein. This process tolerated a variety of functional groups under mild conditions. Further diversification of pyrazoles was also investigated, which provided its potential for drug discovery.
