Byline: Muge Guleli (1), Safiye S. Erdem (2), Nuket Ocal (1), Ihsan Erden (3), Ozlem Sari (4) Keywords: Isoxazoles; 1,8-Naphthyridines; Catalyst; Conjugated heterocycles; Computational studies Abstract: An efficient and general method for the synthesis of substituted 3,4-dimethylisoxazolo[5,4-b]pyridine-5-carboxamide and benzo[b][1,8]naphthyridine-3-carboxamide derivatives by using 2,2,6-trimethyl-4H-1,3-dioxin-4-one, benzyl amine, aromatic aldehydes, 2-aminoquinoline, or 5-amino-3-methylisoxazole in the presence of a catalytic amount of p-toluenesulfonic acid or iodine is described. The formation of the products was investigated and the results obtained were also supported by theoretical calculations. Author Affiliation: (1) 0000 0001 2337 3561, grid.38575.3c, Faculty of Arts and Sciences, Department of Chemistry, Yildiz Technical University, Davutpasa Campus, 34220, Esenler-Istanbul, Turkey (2) 0000 0001 0668 8422, grid.16477.33, Faculty of Arts and Sciences, Chemistry Department, Marmara University, 34722, Goztepe, Istanbul, Turkey (3) 0000000106792318, grid.263091.f, Department of Chemistry and Biochemistry, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA, 94132, USA (4) 0000 0004 0399 5752, grid.411224.0, Department of Chemistry, KA[+ or -]rsehir Ahi Evran University, 40100, KA[+ or -]rsehir, Turkey Article History: Registration Date: 24/12/2018 Received Date: 14/08/2018 Accepted Date: 24/12/2018 Online Date: 09/01/2019 Article note: This paper is dedicated to Prof. Nuket Ocal. During the revision process of this manuscript, our dear colleague and friend, Prof. Nuket Ocal, tragically passed away. We are deeply grateful to Dr. Ocal's tireless efforts, dedication and her--and her students'--invaluable contributions to this project. Electronic supplementary material The online version of this article ( https://doi.org/10.1007/s11164-018-03721-z) contains supplementary material, which is available to authorized users.