Direct N-heterocyclization of hydrazines to access styrylated pyrazoles: synthesis of 1,3,5-trisubstituted pyrazoles and dihydropyrazoles
作者:Vunnam Venkateswarlu、Jaspreet Kour、K. A. Aravinda Kumar、Praveen Kumar Verma、G. Lakshma Reddy、Yaseen Hussain、Aliya Tabassum、Shilpi Balgotra、Sorav Gupta、Abhinandan D. Hudwekar、Ram A. Vishwakarma、Sanghapal D. Sawant
DOI:10.1039/c8ra04550j
日期:——
microwave-assisted method has been developed for the synthesis of tri-substituted pyrazoles via direct N-heterocyclization of hydrazines with metal-acetylacetonate and -dibenzylideneacetonate without using any base or additives. Most importantly, the synthesis of 1-aryl-5-phenyl-3-styryl-1H-pyrazoles was achieved in a single step using hydrochloride salt of various phenylhydrazines and this is the first
Abstract An efficient and novel protocol for pyrazole synthesis has been developed by using fluoroboric acid as the acid catalyst. Simple and easily available 1,3-diketone and hydrazine derivatives are taken as the substrates for this purpose. The reaction entails mild reaction conditions and produces desired pyrazoles in good to excellent yields. Easy accessibility, easy handling, broad substrate
Oxone-DMSO Triggered Methylene Insertion and C(sp<sup>2</sup>)−C(sp<sup>3</sup>)-H−C(sp<sup>2</sup>) Bond Formation to Access Functional Bis-Heterocycles
作者:Jaspreet Kour、Vunnam Venkateswarlu、Praveen K. Verma、Yaseen Hussain、Gurudutt Dubey、Prasad V. Bharatam、Subash C. Sahoo、Sanghapal D. Sawant
DOI:10.1021/acs.joc.9b03477
日期:2020.4.3
Metal-free insertion of a methylene group was achieved for the construction of a new C(sp2)–C(sp3)-H–C(sp2) bond in order to prepare novel bis-heterocyclic scaffolds. The complete mechanistic investigations included experimental study and DFT calculations, and various symmetric and unsymmetric bis-pyrazoles as well as other pyrazole-based bis-heterocyclic molecules were prepared in moderate to high
TBAX/Oxone‐Mediated Halogenation of Pyrazoles and Other Heterocycles: An Entry to Important Cross‐Coupling Reactions
作者:Jaspreet Kour、Pratiksha Khajuria、Alpa Sharma、Sanghapal D. Sawant
DOI:10.1002/asia.202200778
日期:2022.11.16
A facile green approach has been established for halogenation of pyrazoles and different heterocycles via a microwave-mediated protocol using TBAX/Oxone in EtOH. Applications and extension of the method have been demonstrated by presenting various coupling reactions of halogenated pyrazoles.