cis/trans-Isochromanones. DMAP induced cycloaddition of homophthalic anhydride and aldehydes |
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Authors: | Milen G Bogdanov |
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Institution: | Faculty of Chemistry, Sofia University, 1, J. Bouchier Ave., 1164 Sofia, Bulgaria |
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Abstract: | Homophthalic anhydride (1) reacts with wide variety of aromatic aldehydes, in the presence of chloroform and DMAP (N,N-dimethyl-4-amino-pyridine) at room temperature, to give in high yields cis- and trans-1-oxo-isochroman-4-carboxylic acids. Under these conditions, the trans-isomer is predominant and formation of Perkin-type products was not observed in contrast to the reaction carried out in the presence of pyridine. The unexpected trans-6-oxo-11-thiophen-2-yl-11,12-dihydro-6H-dibenzoc,h]chromene-12-carboxylic acid methyl ester (8) was isolated when the reaction between 1 and thiophene-2-carbaldehyde was carried out in pyridine. |
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Keywords: | Homophthalic anhydride Aldehydes Cycloaddition DMAP Pyridine Isochroman-4-carboxylic acids |
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