An Efficient Synthesis of Coumarino[4,3-d]pyrazolo[3,4-b]-pyridine Derivatives Catalyzed by Silica Sulfuric Acid under Microwave Irradiation

Abstract

[3,4-b]pyridine derivatives were synthesized by the reaction of 3-acylcoumarin with 5-aminopyrazole catalyzed by silica sulfuric acid under microwave irradiation. This method has the advantages of short reaction times (20～30 min), excellent selectivity, good yields, and simple operation as well as environmental friendly. The structures of the products were identified by IR, NMR, and HRMS spectra.

Alcohol Participates in the Synthesis of Functionalized Coumarin-Fused Pyrazolo[3,4-b]Pyridine from a One-Pot Three-Component Reaction

“…In the early literature reports of our group [44], the coumarino[4,3-d]pyrazolo[3,4-b]pyridine derivative ( 3a ) was synthesized by the reaction of 3-acylcoumarin ( 1a ) with 5-aminopyrazole ( 2a ) catalyzed by silica sulfuric acid (SSA) in EtOH at 90 °C for 20 min under microwave irradiation (Scheme 1).…”

“…Therefore, development and introduction of a convenient, efficient method for the synthesis of coumarin-fused pyrazolo[3,4- b ]pyridine is highly desirable for their immense pharmacological potential. As a part of our research on the synthesis of novel functionalized heterocyclic derivatives [40,41,42,43,44,45,46], in the current paper, we report a novel three-component domino reaction for the synthesis of functionalized coumarin-fused pyrazolo[3,4- b ]pyridine derivatives using silica sulfuric acid as the catalyst. It worth mentioning that participation of alcohols in construction of coumarin derivatives is described for the first time.…”

One-Pot Synthesis of 3-Functionalized 4-Hydroxycoumarin under Catalyst-Free Conditions

“…To date, GAP chemistry has been used in many asymmetric reactions [ 23 , 24 , 25 ] and MCRs [ 26 , 27 , 28 ]. As part of our current studies on the development of environmentally friendly routes to heterocyclic compounds [ 29 , 30 , 31 , 32 ], we now report an efficient and clean synthesis of 3-functionalized 4-hydroxycoumarin derivatives under catalyst-free conditions.…”