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.
Subject(s)
Bridged Bicyclo Compounds/chemistry , Pyrazoles/chemical synthesis , Pyridines/chemical synthesis , Amines/chemistry , Cyclization , Molecular Structure , Pyrazoles/chemistry , Pyridines/chemistryABSTRACT
A new three-component bicyclization for the efficient synthesis of a fused pyrano[2,3-b]pyridine library has been developed. The syntheses were achieved by reacting diverse C,O-containing nucleophiles, aldehydes, and 2-aminoprop-1-ene-1,1,3-tricarbonitrile under microwave irradiation, providing 50 examples of chemically and biomedically significant pyrano[2,3-b]pyridine analogues with the concomitant formation of two new rings and four σ bonds. This procedure features short reaction times, low-cost, and easily available starting materials, reliable scalability and mild reaction conditions, as well as operational simplicity.
Subject(s)
Pyrans/chemical synthesis , Pyridines/chemical synthesis , Combinatorial Chemistry Techniques , Cyclization , Microwaves , Pyrans/chemistry , Pyridines/chemistryABSTRACT
An efficient combination between the Passerini three-component reaction and aldol condensation has been developed for the synthesis of bicyclic isocoumarins with different substituted patterns via solvent-dependent domino pathways. These two operationally friendly methods simultaneously install C-O and C-C bonds in a one-pot manner, allowing the utilization of low-cost and readily accessible 2-formylbenzoic acid, isocyanides, and arylglyoxals. Mechanisms of formation of different substituted isocoumarin derivatives are also proposed.
Subject(s)
Isocoumarins/chemical synthesis , Aldehydes/chemistry , Catalysis , Cyanides/chemistry , Isocoumarins/chemistry , Molecular Structure , StereoisomerismABSTRACT
Readily available triethylammonium 1-(2-oxoindolin-3-ylidene)-2-aroylethanethiolates are efficiently converted into a variety of fully substituted thiophene derivatives by copper(I)-catalyzed denitrogenative reactions with terminal alkynes and N-sulfonyl azides. This new reaction simultaneously installs C-N, C-S, and C-C bonds, allowing direct formation of highly functionalized thiophenes with a wide diversity in substituents in a one-pot manner. A plausible mechanism for the domino process is proposed.
Subject(s)
Copper/chemistry , Iodides/chemistry , Thiophenes/chemical synthesis , Alkynes/chemistry , Azides/chemistry , Catalysis , Molecular Structure , Thiophenes/chemistryABSTRACT
An efficient, three-component strategy for the improved synthesis of multifunctionalized 6,7-dihydrobenzofuran-4(5H)-ones under microwave irradiation in ethyl alcohol within short periods has been established. The synthesized benzofuran-4(5H)-ones have been readily converted into polyfunctionalized cinnoline-4-carboxamides by treating with hydrazine hydratein in the same solvent through a regioselective ring-opening of the furan. Tedious workup procedures can be avoided because of the direct precipitation of products from the reaction solution by water addition, thus rendering the two-steps process ecofriendly.