449758-17-2Relevant articles and documents
Green protection of pyrazole, thermal isomerization and deprotection of tetrahydropyranylpyrazoles, and high-yield, one-pot synthesis of 3(5)-alkylpyrazoles
Ahmed, Basil M.,Mezei, Gellert
, p. 24081 - 24093 (2015)
We report a new synthetic approach that opens up the possibility of large scale, one-pot pyrazole derivatization by a wide variety of functionalities, including alkyl, halogen, hydroxyl, amino, azido, carbonyl, and organo-element (e.g., B, Si, P) groups. The approach is illustrated by the highly efficient synthesis of fourteen 3(5)-alkylpyrazoles, including the novel isopentyl- and n-hexadecyl derivatives, as well as 1,6-bis(pyrazol-3(5)-yl)hexane. The value of the new approach lies in the discovery of a green (solvent- and catalyst-free, quantitative) protection of pyrazole, followed by a high-yield lithiation/alkylation/deprotection sequence in the same pot. For the first time, the corresponding N-tetrahydropyran-2-yl (THP) intermediates have been isolated and characterized. Thermal isomerization of the 5-alkyl-1-(THP) to the 3-alkyl-1-(THP) isomer is shown to be an advantageous, green alternative to the acid-catalyzed, sequential protecting-group switching methodology in pyrazole chemistry. The X-ray crystal structures of 1,6-bis(pyrazol-3(5)-yl)hexane and 5-n-hexadecyl-1-(tetrahydropyran-2-yl)pyrazole reveal supramolecular architectures that shine light on the remarkable affinity for water and unexpected insolubility in organic solvents of alkylene-bridged bis(pyrazoles). 3(5)-Alkylpyrazoles are obtained in high yield from pyrazole by a one-pot procedure.
Decatungstate-Mediated C(sp3)–H Heteroarylation via Radical-Polar Crossover in Batch and Flow
Capaldo, Luca,Frederick, Michael O.,García-Losada, Pablo,Laudadio, Gabriele,Mateos, Carlos,No?l, Timothy,Nu?o, Manuel,Nyuchev, Alexander V.,Rincón, Juan A.,Wan, Ting
supporting information, p. 17893 - 17897 (2021/07/14)
Photocatalytic hydrogen atom transfer is a very powerful strategy for the regioselective C(sp3)–H functionalization of organic molecules. Herein, we report on the unprecedented combination of decatungstate hydrogen atom transfer photocatalysis with the oxidative radical–polar crossover concept to access the direct net-oxidative C(sp3)–H heteroarylation. The present methodology demonstrates a high functional group tolerance (40 examples) and is scalable when using continuous-flow reactor technology. The developed protocol is also amenable to the late-stage functionalization of biologically relevant molecules such as stanozolol, (?)-ambroxide, podophyllotoxin, and dideoxyribose.
METHODS FOR THE PREPARATION OF 5-BROMO-2-(3-CHLORO-PYRIDIN-2-YL)-2H-PYRAZOLE-3-CARBOXYLIC ACID
-
Paragraph 0281-0284, (2021/04/23)
Described herein are novel methods of synthesizing 5-Bromo-2-(3-chloro-pyridin-2-yl)- 2H-pyrazole-3-carboxylic acid from pyrazole or pyrazole derivatives.
GLYCOLATE OXIDASE INHIBITORS FOR THE TREATMENT OF DISEASE
-
Paragraph 002214; 002215; 002217; 002239; 002240; 002241, (2019/07/17)
Described herein are compounds, methods of making such compounds, pharmaceutical compositions and medicaments containing such compounds, and methods of using such compounds to treat or prevent diseases or disorders associated with the enzyme glycolate oxidase (GO). Such diseases or disorders include, for example, disorders of glyoxylate metabolism, including primary hyperoxaluria, that are associated with production of excessive amounts of oxalate.
