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Novel spirooxindole-furo[2,3-c]pyrazole derivatives containing both biologically active pyrazole and spirooxindole-furan templates are synthesized via single-pot two-step four-component reaction involving hydrazine, β-keto ester, isatin derivatives and pyridinium ylide catalyzed by triethylamine in EtOH under microwave irradiation (MWI). In this domino protocol, five bonds (2C–C, C – O, C–N, C = N) and two new rings are efficiently formed via initial Knoevenagel, subsequent Micheal and final heterocyclization reactions. High yields, short reaction time (10–15 min), operational simplicity, absence of any tedious workup or purification and avoidance of hazardous or toxic reagents/solvents are the salient features of this eco-friendly methodology. [ABSTRACT FROM AUTHOR]

p-Toluenesulfonic acid was applied as an efficient, non-toxic and solid acid catalyst for the one-pot, four-component condensation between 2-hydroxy-1,4-naphthoquinone, benzene-1,2-diamine, cyclic 1,3-dicarbonyl compounds and isatin or ninhydrin to afford the corresponding novel spiro[benzo[a]chromeno[2,3-c]phenazine] derivatives via a new two-step domino protocol under conventional heating and microwave irradiation. This solvent-free process produces biologically considerable heterocycles with the formation of five new bonds (two C–C, two C˭N, and one C–O) and two new rings in a single operation and this effective green process provides considerable advantages such as: operational simplicity, very short reaction time, high yields, absence of any tedious process or purification, and it avoids hazardous reagents/solvents. [ABSTRACT FROM AUTHOR]

1,4-Diazabicyclo[2.2.2]octane (DABCO) has been used as an efficient and reusable solid base catalyst for the rapid and green synthesis of pyran annulated heterocyclic ring systems by the condensation reaction of various activated CH-acids and tetracyanoethylene under conventional heating and microwave irradiation in solvent-free conditions. Excellent yield, very short reaction time (2–5 min), operatinal simplity, easy work-up procedure, avoidance of hazardous or toxic catalysts, and organic solvents are the main advantages of this green methodology which makes it more economic than the other conventional methods. [ABSTRACT FROM AUTHOR]