The first synthesis of furocoumarin dimers

Dihydrofurocoumarinones - new useful intermediates for substituted and condensed furocoumarins

“…We have earlier found dihydrofurocoumarin-9-ones to be very useful intermediates for substituted and condensed furocoumarin synthesis [20][21][22][23][24][25][26][27][28]. Survey of our previous studies and unpublished results is given in this paper.…”

“…Survey of our previous studies and unpublished results is given in this paper. compound 2b with a good yield [24]. For example, treatment of 2b by bromine in acetic acid or 1,4-dioxane provides its mono-and dibromination.…”

New Synthetic Routes to Furocoumarins and Their Analogs: A Review

“…We have studied the Fries rearrangement of 7-acyloxycoumarins in detail [20][21][22]. Some of the results are given below.…”

“…To a large extent, the reactivity of dihydrofurocoumarinones such as 20, 45 or 47 is based on their keto-enol tautomerism (Scheme 21). Tautomeric transformations of these compounds have been studied by spectral and computational methods [27,28]. For example, the longest-wavelength absorption band in the UV spectrum of 20 is at 330 nm in methanol and at 285 nm in carbon tetrachloride.…”

“…Thus, rearrangement of 18 in the presence of 7-hydroxy-4-methylcoumarin (21) gives equimolar amounts of a 4-methyl derivative 20 and its analog 22, lacking the methyl group (Scheme 8) [20]. Substrates which have a substituent at position 8 of the coumarin ring system, undergo rearrangement into position 6 [22].…”