Tetrahedron

4, 6-dimethyl-2h, 8h-benzo [1, 2-b: 5, 4-b'] dipyran-2, 8-dione. formation of linear and angular isomers in the pechmann reaction

AG Osborne

Index: Osborne, A. G. Tetrahedron, 1983 , vol. 39, # 9 p. 1523 - 1528

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Citation Number: 9

Abstract

The structure of Hantzsch and Zürchers “dimethyldicoumarin” obtained from resorcinol or 7- hydroxy-4-methylcoumarin and ethylacetoacetate has been confirmed as the linear title compound 1. peri-Substituent effects in 1H and 13C NMR spectroscopy have been used to differentiate between the lin and ang isomers, the ang Me groups being deshielded. A set of rules to govern the formation of lin/ang isomers has been proposed.