Search

A series of furo[2,3- d ]pyrimidine derivatives were synthesized via the [3+2] cyclization of pyrimidine-4,6-diol and a variety of nitroolefins at catalyst-free conditions. The reaction is easy to perform simply mixing inexpensive starting materials in water under conventional heating at 90 °C. The reaction proceeds at a fast speed within 1.5–2 h and gives the high biological and pharmacological active substituent furo[2,3- d ]pyrimidine derivatives with good to high yields. Mechanism of formation of these furo[2,3- d ]pyrimidine derivatives are also proposed. [ABSTRACT FROM AUTHOR]

Treatment of nitroolefins and o -phenylenediamine with silica gel catalyst produced quinoxalines mainly in THF, but gave benzimidazoles efficiently in water. Such a solvent-dependent chemoselective reaction has prominent features of affording two cyclized products selectively with the same substrate, short reaction time, operational simplicity, as well as available starting materials and nontoxic catalysts. In addition, the scope and limitations were explored and a plausible reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

• An efficient and green strategy for synthesis of 1,6-naphthyridines has been established. • The 1,6-naphthyridines are obtained catalyzed by solid acid under ultrasonic irradiation. • The ultrasonic irradiation as thermal and kinetic energy source shorten reaction time and heighten yield. An efficient and highly eco-friendly approach to poly-substituted 1,6-naphthyridine derivatives with good to excellent yield has been reported using simple and readily available 4-aminopyridinone, aromatic aldehyde or isatin, and 1,3-cyclohexanedione as substrates. The method features low-cost and readily accessible starting materials, green ultrasonic irradiation in water, recycle heterogeneous solid acid catalyst, broad substrate scope as well as simple one-pot operation make this strategy highly attractive. Mechanistic studies indicate that this transformation involves Knoevenagel condensation, Michael addition, and cyclization sequence. [ABSTRACT FROM AUTHOR]

A simple and efficient procedure for the synthesis of pyrazoloisoquinoline and pyrazolopyridine derivatives by one-pot three-component condensation of aminopyrazoles, aldehydes, and cycloketones in water using carbonaceous material as solid acid catalyst is described. The procedure offers several advantages such as simple experimental and work-up procedures, high yield, recovery, and reusability of metal-free solid acid heterogeneous catalyst along with tolerance of a wide range of functional groups. [ABSTRACT FROM AUTHOR]

• A new domino approach for synthesis of pyrrolo[3,2- c pyridin-4-ones has been established. • The one-pot two-step four component strategy makes the reaction attractive. • The remarkable feature of the process is the formation of five C–N, C–C bonds initiated by sole acetic acid. A direct and metal-free access toward poly-substituted pyrrolo[3,2- c pyridin-4-one and its analogues have been established through a simple four-component, two-step reaction of 4-hydroxy-6-methyl-2 H -pyran-2-one, two amine molecules, and β -nitrostyrenes. The reaction allows the formation of five different C–N, C–C bonds by the multiple bond cleavage only using acetic acid as catalyst and solvent. The advantages of broad substrate scope, efficient and metal-free reaction conditions, inexpensive and readily available starting materials as well as simple one-pot two-step operation, make the strategy highly attractive. This transformation in acetic acid resulted in the rapid establishment of functional bioactive poly-substituted pyrrolo[3,2- c pyridin-4-one derivatives. [ABSTRACT FROM AUTHOR]