Four-component bicyclization approaches to skeletally diverse pyrazolo[3,4-b]pyridine derivatives.

ABSTRACT: A novel four-component bicyclization strategy has been established, allowing a flexible and practical approach to 37 examples of multicyclic pyrazolo[3,4-b]pyridines from low-cost and readily accessible arylglyoxals, pyrazol-5-amines, aromatic amines, 4-hydroxy-6-methyl-2H-pyran-2-one, and cyclohexane-1,3-diones. The polysubstituted cyclopenta[d]pyrazolo[3,4-b]pyridines were stereoselectively synthesized through a microwave-assisted special [3+2+1]/[3+2] bicyclization with good control of the spatial configuration of exocyclic double bonds. The novel [3+2+1]/[2+2+1] bicyclization resulted in 17 examples of unreported pyrazolo[3,4-b]pyrrolo[4,3,2-de]quinolones. Reasonable mechanisms for forming two new types of multicyclic pyrazolo[3,4-b]pyridines are also proposed.

SUBMITTER: Tu XJ 

PROVIDER: S-EPMC4242041 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature