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This article discusses the synthesis of pyrido[2,3-d]pyrimidines, which are important heterocycles found in many pharmaceutically active molecules. The traditional methods for synthesizing these compounds are described, as well as the limitations of these methods. The article then presents a new catalytic system using 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)/tert-Butyl Nitrite (TBN)/O2 for the synthesis of pyrido[2,3-d]pyrimidines. The reaction conditions and optimization are discussed, and the results show promising yields. This research provides a new and efficient method for the synthesis of pyrido[2,3-d]pyrimidines with potential bioactivities. The given document presents a table showing the results of control experiments on the reaction of uracils and 1,3-diarylpropenes. The table includes entries for different combinations of reactants and the corresponding products and yields. The experiments indicate that both TBN and O2 promote the reaction. The table provides specific details about the reactants and products, as well as the corresponding yields. This document describes a novel and efficient method for synthesizing pyrido[2,3-d]pyrimidines/thiopyrido[2,3-d]pyrimidines using easily available starting materials. The reaction involves oxidative coupling, intramolecular cyclization, [Extracted from the article]

Keywords: tandem reaction; oxidative coupling; TBHP; 4-aminocoumarin; benzopyrano[4,3- b ]pyridines EN tandem reaction oxidative coupling TBHP 4-aminocoumarin benzopyrano[4,3- b ]pyridines 2683 2690 8 08/17/23 20230901 NES 230901 Graph Pyridine is one of the most important scaffolds and it is present in many natural products, pharmaceuticals, agrochemicals, optical and electronic materials. 2019, 125: 93 30 Almasalma, A A. Mejía, E. Chem. Eur. J. 2018, 24: 12269 31 Sugiishi, T. Nakamura, H. J. Am. Chem. Soc. 2012, 134: 2504 32 Li, C.-J. Acc. Chem. Int. Ed. 2008, 47: 7075 35 Li, Z. Li, C.-J. J. Am. Chem. Soc. 2006, 128: 56 36 Li, Z. Li, C.-J. J. Am. Chem. Soc. 2005, 127: 6968 37 Boess, E. Van Hoof, M. Birdsall, S L. Klussmann, M. J. Org. [Extracted from the article]

[Display omitted] A tandem reaction of 2-aminonaphthoquinone/4-aminocoumarins with 1,3-diarylpropenes mediated by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)/ tert -butyl nitrite (TBN)/O 2 is disclosed. It involves oxidative coupling, intramolecular annulation and dehydro-aromatization reaction, which provides an efficient and mild method for the synthesis of 1-aza-anthraquinones and pyridocoumarins. [ABSTRACT FROM AUTHOR]