CCI.—The coumarin condensation

Abstract

and others found t h a t phenols condense with ethyl acetoacetate and malic acid in t h e presence of concentrated sulphuric acid to form members of t h e coumarin series. Different phenols were found to condense with varying degrees of readiness; thus phenol, 0 -and p-cresols, quinol, and thymol gave extremely poor yields (phenol furnished not more than 3 per cent. of the theoretical quantity), but resorcinol, orcinol, and pyrogallol condensed very readily. Later, Pechmann (Bey., 1899, 32, 3681) showed t h a t dimethyl-m-aminophenol condensed readily with ethyl acetoacetate, whilst t h e corresponding orthoand para-compounds yielded only traces of coumerins. Still more recently Fries and Klostermann (Bey., 1906, 39, 871) condensed m-cresol with malic acid and ethyl acetoacetate, and showed t h a t a plentiful yield was obtained in each case.

The Chemistry of Coumarins.

“…Pechmann with Kraft (157) and Graeger (155) extended this reaction to other phenols. Dey (64) condensed various phenols with acetonedicarboxylic acid ester and made a systematic study of the reactivity of the coumarin-4-acetic acids thus synthesized: Clayton (48) found that the phenols with alkyl, hydroxy, and dialkylamino groups in the positions marked X in the formulas given below undergo condensa-x^Noh V…”

Application of optically detected magnetic resonance to low temperature solid state photoreactions of halogenated coumarines

“…Optical excitation is provided by a high pressure Hg lamp using Schott filters UG 11. 7-chlorocoumarin (CC) and 7-bromocoumarin (BC) have been synthesized according to [16]. Doping mate¡ such as CC and BC and coumarin have been purified by recrystallisation and sublimation, host materials p-dibromobenzene (DBB) and durene have been extensively zone refined.…”

Molecular self-assembly: 4-formylcoumarins as versatile skeletons for complementary multipoint association via weak (C–H⋯O, C–H⋯F and C–X⋯OC) interactions

“…The precursor 4-methyl-substituted coumarins, viz. 4-methyl, 28 6-chloro-4-methyl, 29 7-chloro-4-methyl, 30 Fig. 6 The crystal packing diagram of 6-fluoro-4-formylcoumarin 5.…”