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Autocatalytic and DMSO-participating regioselective synthesis of N,N-disubstituted pyrimido[4,5-b]quinoline-2,4(1H,3H)-diones from anilines and barbituric acids has been achieved. In this newly developed one-pot tandem reaction, DMSO serves as a solvent cum methine source. Additionally, barbituric acid plays a dual role by acting as a substrate and a catalyst, making this reaction an environmentally benign approach to accessing valuable heterocycles. This method offers an auto-catalytic, additive-free, and operationally simple approach with a wide substrate scope and excellent tolerance for various functional groups. Furthermore, a few controlled experiments were conducted to gain insight into the reaction mechanism. Moreover, large-scale experiments have further enriched this methodology. [ABSTRACT FROM AUTHOR]

We present an efficient approach for synthesizing pyridoquinazolinones in the presence of triflic anhydride utilizing anthranils and 2-chloropyridines as starting materials. In this process, Tf2O initially activates anthranils forming an electrophilic 1-((trifluoromethyl)sulfonyl)benzo[c]isoxazol-1-ium species. This species undergoes an in situ annulation reaction with 2-chloropyridines, resulting in therapeutically useful pyridoquinazolinones. The reaction is tolerant to various functional groups, allowing access to a wide range of substituted pyridoquinazolinones in good yields. Furthermore, the synthesis of euxylophoricine B, known to be an antitumor agent, was also achieved. [ABSTRACT FROM AUTHOR]

Copper‐catalyzed routes have been achieved for the synthesis of 3‐nitroquinolines from readily available nitroolefins and anthranils. This reaction proceeds via the [4+2] cycloaddition between anthranils and nitro‐styrenes under mild reaction conditions to obtain biologically important heterocycles. A wide range of diversely substituted nitro‐olefins and anthranils are successfully employed in this reaction to access a series of 3‐nitro‐quinolines in 81–93% yields. The synthetic utility of the present methodology is also illustrated in this manuscript. [ABSTRACT FROM AUTHOR]

We present an efficient approach for synthesizing pyridoquinazolinones in the presence of triflic anhydride utilizing anthranils and 2-chloropyridines as starting materials. In this process, Tf 2 O initially activates anthranils forming an electrophilic 1-((trifluoromethyl)sulfonyl)benzo[ c ]isoxazol-1-ium species. This species undergoes an in situ annulation reaction with 2-chloropyridines, resulting in therapeutically useful pyridoquinazolinones. The reaction is tolerant to various functional groups, allowing access to a wide range of substituted pyridoquinazolinones in good yields. Furthermore, the synthesis of euxylophoricine B, known to be an antitumor agent, was also achieved.

An acid-mediated and DMSO participant one-pot tandem synthesis of 3-substituted-1-aryl-1 H -pyrazolo-[3,4- b ]quinoline from readily available anilines and pyrazolones was achieved. This method enables regioselective construction of the valuable heterocycles under transition-metal and oxidant-free conditions in which DMSO acts as a methine source as well as solvent making this process an environmentally benign approach. A broad range of diversely substituted aryl amines and pyrazolines are successfully employed in this reaction to access a series of pyrazolo[4,3- c ]quinolones through a novel cascade mechanism. Furthermore, the application and mechanistic studies of the present methodology also demonstrated.