Investigation of the Pechmann Reaction Between 2,7‐Dihydroxynaphthalene and Ethyl Acetoacetate with Different Condensing Agents. Synthesis of Benzocoumarin and Benzochromone Systems and Their Bi‐ and Bis‐derivatives.

Abstract

KOLANCILAR*, H.; OYMAN, U.; J. Indian Chem. Soc. 80 (2003) 9, 853-857; Dep. Chem., Fac. Arts Sci., Univ. Trakya, TR-22030 Edirne, Turk.; Eng.) -M. Bohle

Photophysical characterization of triazole-substituted coumarin fluorophores

“…Obtained in 97% yield. 1 [36,37] 2,7-Dihydroxynapthalene (4.8 g, 29.44 mmol, 1 equiv.) was dissolved in ethyl acetoacetate (9.4 mL, 73.6 mmol, 2.5 equiv.)…”

“…To generate the 7-hydroxy-4-methyl coumarin backbone (1a, 4-methylumbelliferone), resorcinol (5) was reacted with ethyl acetoacetate in a TiCl 4 -catalyzed Pechmann condensation [34]. Two isomers of benzocoumarin were generated from 2,7-dihydroxynapthalene (6) in a sulfuric acidcatalyzed Pechmann condensation with ethyl acetoacetate, providing the angular-(2a) and linear-benzocoumarins (3a) after purification [35][36][37]. A second umbelliferone derivative was generated by a piperidine catalyzed Knoevenagel condensation of diethyl glutaconate with 2,4-dihydroxybenzaldehyde to form compound 4a [38].…”

Synthesis and Characterization of New Helical Coumarins

“…One can easily anticipate the two methyl groups to occupy the opposite sides of the naphthalene plane and hence show helical twist. However, its synthesis has been unsuccessfully attempted previously as well as by us in the current study (Scheme ).…”

“…Reaction of 2,7‐dihydroxynaphthalene furnished monocoumarin 12 , with the second hydroxyl group remaining unaffected (Scheme ) . With the aim to build a molecule with suitable peri interaction, the free hydroxyl group of monocoumarin 12 was then utilized to direct the electrophilic substitution on the C‐10 position.…”