《Orchestrated Triple C-H Activation Reactions Using Two Directing Groups: Rapid Assembly of Complex Pyrazoles》 was published in Angewandte Chemie, International Edition in 2015. These research results belong to Yang, Weibo; Ye, Shengqing; Fanning, Dewey; Coon, Timothy; Schmidt, Yvonne; Krenitsky, Paul; Stamos, Dean; Yu, Jin-Quan. Reference of 3-(tert-Butyl)-1-ethyl-1H-pyrazole-5-carboxylic acid The article mentions the following:
A sequential triple C-H activation reaction directed by a pyrazole and an amide group leads to the well-controlled construction of sterically congested dihydrobenzo[e]indazole derivs I [R1 = H, 4-Me, 3-Me, 3,4-diMe, 4-Ph, 4-F, etc.; R2 = Me, (CH2)2Ph, (CH2)3Ph; R3 = Me, Et, iBu, cyclohexylmethyl; R2R3=(CH2)5; R4 = Me, Et]. This cascade reaction demonstrates that the often problematic competing C-H activation pathways in the presence of multiple directing groups can be harvested by design to improve step economy in synthesis. Pyrazole as a relatively weak coordinating group is shown to direct Csp3-H activation for the first time. In the experiment, the researchers used 3-(tert-Butyl)-1-ethyl-1H-pyrazole-5-carboxylic acid(cas: 195447-83-7Reference of 3-(tert-Butyl)-1-ethyl-1H-pyrazole-5-carboxylic acid)
3-(tert-Butyl)-1-ethyl-1H-pyrazole-5-carboxylic acid(cas: 195447-83-7) belongs to pyrazoles. Pyrazole derivatives have been reported to exhibit a wide range of applications in medicinal chemistry and pharmacology. A large number of drugs incorporating pyrazole structure have been utilized as partial agonists for nicotinic acid receptors, antidepressants, antimicrobial agents, antiviral agents, and antifungal agents solely or along with the combination of other structural motifs.Reference of 3-(tert-Butyl)-1-ethyl-1H-pyrazole-5-carboxylic acid
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics