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Issue 25, 2012
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Sequential approach to the synthesis of ‘U and Z’ shaped polycyclic heteroarenes

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Abstract

The synthesis of three new classes of heteroarenes, built through the sequential fusion of naphthalene, benzo/naphtho[b]oxepine and thiochromene rings with pyran and pyrimidine ring systems to give ‘U and Z’ shaped structural frameworks is reported. The methodology is based on the synthesis of pyran fused intermediates, 1-methylthio-3-oxo-5,6-dihydro-3H-benzo[f]chromene-2-carbonitrile (3), 4-methylthio-2-oxo-5,6-dihydro-2H-benzo/naphtho[b]pyrano[2,3-d]oxepine-3-carbonitriles (10, 20) and 4-methylthio-2-oxo-2,5-dihydrothiochromeno[4,3-b]pyran-3-carbonitriles (15) from the reaction of 2-tetralone, benzo/naphtho[b]oxepin-5-ones and thiochromen-4-ones with methyl 2-cyano-3,3-dimethylthioacrylate respectively. Further condensation of intermediates 3, 10, 20 and 15 with amidines led to the formation of tetracyclic ‘U’ shaped 4-amino-2-aryl-7,8-dihydro-5-oxo-5H-naphtho[2,1-b]pyrimido[4,5-d]pyrans (8) and ‘Z’ shaped 4-amino-2-aryl-5-oxo-12,13-dihydro-5H-benzo/naphtho[b]oxepino[5,4-b]pyrimido[4,5-d]pyrans (12, 22) and 4-amino-2-aryl-5-oxo-5,12-dihydrothiochromeno[4,3-b]pyrimido[4,5-d]pyrans (17). Compound 12f forms a chain of dimers through N–H⋯O interactions as indicated by the X-ray structure analysis, and the quantum chemical calculations performed at the MP2 level indicate that this interaction energy is 10 kJ mol−1.

Graphical abstract: Sequential approach to the synthesis of ‘U and Z’ shaped polycyclic heteroarenes

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Publication details

The article was received on 23 Jan 2012, accepted on 19 Mar 2012 and first published on 21 Mar 2012


Article type: Paper
DOI: 10.1039/C2OB25173F
Citation: Org. Biomol. Chem., 2012,10, 4977-4986
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    Sequential approach to the synthesis of ‘U and Z’ shaped polycyclic heteroarenes

    H. K. Maurya, S. K. Gautam, R. Pratap, V. K. Tandon, A. Kumar, V. Bajpai, B. Kumar and V. J. Ram, Org. Biomol. Chem., 2012, 10, 4977
    DOI: 10.1039/C2OB25173F

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