Conventional and Microwave‐Assisted Synthesis and Biological Activity Study of Novel Heterocycles Containing Pyran Moiety

Abstract

Under both conventional and microwave methods, 2‐amino‐4 H ‐pyran‐3‐carbonitrile derivative 1 was synthesized and reacted with different reagents. Thus, 2‐amino‐4 H ‐pyran‐3‐carbonitrile derivative was treated with chloroacetyl chloride, phenyl isocyanate, cyanoacetic acid, benzoyl chloride, triethyl orthoformate, acetic anhydride/H 2 SO 4 , arylidene malononitrile, urea, and/or p ‐aminosulphaguanidine producing chloroacetamide, 3‐phenylurea, cyanoacetamide, N ‐benzoylpyran, ethylformimidate, pyranopyrimidin‐4‐one, pyranopyridine, pyranopyrimidin‐2‐one, and pyranopyrimidin‐2‐imine derivatives, respectively. Meanwhile, compound 1 was reacted with ethyl bromoacetate, phenacyl bromide, phthalic anhydride, different aromatic amines, and/or acetic acid/H 2 SO 4 to produce 5‐aminopyrano[2,3‐ b ]pyrrole‐6‐carboxylate, dihydropyrano[2,3‐ b ]pyrrole‐6‐yl‐(phenyl)methanone, 1,3‐dioxoisoindolinyl pyran, 1,4‐dihydropyridine, and 2‐hydroxy‐1,4‐dihydropyridine derivatives, respectively. On the other hand, when compound 1 was allowed to react with maleic anhydride and/or hydrazine hydrate, pyran‐4‐oxobut‐2‐enoic acid and 3‐aminopyranopyrazole derivatives were obtained, respectively. Reaction of pyran‐4‐oxobut‐2‐enoic acid with malononitrile under different conditions gave 2‐(furan‐2‐yl)‐4 H ‐pyran and 2‐(4 H ‐pyran‐2‐yl)‐1 H ‐pyrrole derivatives, while condensation of 3‐aminopyranopyrazole with benzaldehyde gave 1,4‐dihydropyrano[2,3‐ c ]pyrazol‐3‐yl‐1‐phenylmethanimine derivative. The newly synthesized compounds were characterized by the spectroscopic tools IR, 1 H‐NMR, 13 C‐NMR, MS, and elemental analysis. Some of these compounds have been screened in vitro for antimicrobial activity against different strains of bacteria and fungi and also were tested against two cancer cell lines: mammary gland breast cancer (MCF‐7) and colon cancer (HCT‐118).