A Convenient Method for the Synthesis of Chromeno[4,3-b]pyridines Via Three-component Reaction.

AIM AND OBJECTIVE: The importance of Chromeno[4,3-b]pyridines in bioactive compounds, highlighted the ongoing research on developing novel methods for the construction of this heterocyclic scaffold. Regarding the advantageous features of multi-component reactions in organic synthesis, we will try to synthesize pyridocoumarins through this method. MATERIALS AND METHODS: Chromeno[4,3-b]pyridines were conveniently prepared from a threecomponent condensation reaction between 4-hydroxy coumarin, ammonia and ethyl 2,4-dioxo-4- arylbutanoates in refluxing n-propanol. The synthesized compounds were characterized by NMR, IR and Mass spectroscopy. RESULTS: The reaction proceeded through an in situ formed 4-amino coumarin, affording eight new target compounds in good yields. CONCLUSION: This method introduce a novel approach to ethyl 4-aryl-5-oxo-5H-chromeno[4,3- b]pyridine-2-carboxylate derivatives and allow organic chemists to prepare 4-aminocoumarin in reaction medium.

Design, synthesis and in vitro α-glucosidase inhibition of novel dihydropyrano[3,2-c]quinoline derivatives as potential anti-diabetic agents.

A novel series of dihydropyrano[3,2-c]quinoline derivatives 6a-q were synthesized and evaluated for their in vitro α-glucosidase inhibitory activities. All newly synthesized compounds displayed potent α-glucosidase inhibitory activity in the range of 10.3 ±â€¯0.3 µM-172.5 ±â€¯0.8 µM against the yeast α-glucosidase enzyme when compared to the standard drug acarbose (IC50 = 750.0 ±â€¯1.5 µM). Among these compounds, compounds 6e and 6d displayed the most potent α-glucosidase inhibitory activity (IC50 = 10.3 ±â€¯0.3 and 15.7 ±â€¯0.5 µM, respectively). The kinetic analysis of the most potent compounds 6e and 6d revealed that compound 6e inhibited α-glucosidase in an uncompetitive manner (Ki = 11 µM) while compound 6d was a non-competitive inhibitor (Ki = 28 µM) of the enzyme. Then, the cytotoxicity of the most potent compounds (i.e., compounds 6a, 6d, 6e, 6 g, 6j, and 6l) were evaluated for toxicity using the breast cancer cell lines MDA-MB231, MCF-7, and T-47D by using a MTT assay, and no toxicity was observed.