Design and synthesis of new and significative bifunctional compounds containing two pyrazolo[3,4‐b]pyridine nucleis through multicomponent reaction under microwave irradiation

Abstract

A series of new and significative bifunctional compounds containing two pyrazolo[3,4‐b]pyridine moieties has been synthesized through a rapid one‐pot three‐component reaction of dialdehyde, 5‐amino‐3‐methyl‐1‐phenylpyrazole and active methylene compounds in glycol under microwave irradiation without catalyst. The method has the advantages of good yield (85‐98%), short route and reaction time (45‐300s), wide reaction scope and easy work‐up procedure.

Three-component reactions of aromatic amines, 1,3-dicarbonyl compounds, and α-bromoacetaldehyde acetal to access N-(hetero)aryl-4,5-unsubstituted pyrroles

“…KI may play a key role in the last step, and we suspected that it can promote the removal of bromide. Although 5a can theoretically be synthesized through a three-component reaction of 1b , 2a , and an appropriate aldehyde, for example, acetaldehyde [ 50 – 51 ] owing to the insufficient reactivity of aliphatic aldehydes, the reaction in Scheme 6 should be a wise choice for the synthesis of products similar in type to 5a . This point deserves further investigation.…”

A Green Approach to the Synthesis of Biologically Important Indeno[2,1‐e]pyrazolo[5,4‐b]pyridines via Microwave‐assisted Multi‐component Reactions in Water

“…Not long ago, we synthesized a bifunctional compound (1, Figure 2) containing two indeno[2,1-e]-pyrazolo [5,4-b]pyridine skeletons in glycol under MWI. 32 However, this reaction using organic solvent, which is not environmental-friendly compared with water, was still not a green approach. Therefore, the development of green methods for the synthesis of indeno[2,1-e]pyrazolo [5,4-b]pyridines is strongly desirable.…”