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
Pyrazole and benzothiazole palladacycles: stable and efficient catalysts for carbon–carbon bond formation
作者:Xinjie Gai、Ronald Grigg、M. Imran Ramzan、Visuvanathar Sridharan、Simon Collard、Jayne E. Muir
DOI:10.1039/b005452f
日期:——
Cyclopalladated phosphine free pyrazole complexes 1 and benzothiazole complexes 2 are excellent catalysts for the Heck vinylation of aryl iodides and termolecular queuing cascades, leading to turnover numbers of >106 in some cases, at moderate temperatures; these catalysts show high thermal stability and are not sensitive to moisture and air.
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