More efficient and preferably more convenient and greener synthetic solutions in coumarin scaffold functionalization are in steady demand. The Duff ortho-formylation of unsubstituted umbelliferone was revised in this study. The reaction conditions were optimized based upon data from the literature analysis and resulted in unexpectedly rapid ortho-formylation of umbelliferone, yielding a mixture of ortho-formyl position isomers. Thorough studies on the separation of ortho-formylated umbelliferones using chromatographic and recrystallization methods as well as the evaluation of their solubility in common organic solvents led to complete resolution of 8-formyl- and 6-formylumbelliferones. The precise protocol for simultaneous preparation, extraction, and purification of 8-formyl- and 6-formylumbelliferones is provided, and the prospective studies of biological and pharmacological activities of these compounds are synopsized.

Photo-controlled or photo-regulated molecules, especially biologically active and operating in physiological conditions, are in steady demand. Herein, furocoumaric and furocoumarinic acids being (Z/E)-isomers relative to each other were obtained in two stages starting from psoralen: the alkaline solvolysis of psoralen led to furocoumaric acid, which was further Z → E photoisomerized (365 nm) to furocoumarinic acid. The kinetics of Z → E photoisomerization was monitored by HPLC and UV-vis spectrophotometry. Photophysical characteristics in the aqueous phase for both acids, as well as the reversibility of (Z/E) photoisomerization process, were also assessed. Furocoumarinic acid was found to be visibly fluorescent at pH 2.0–12.0, with the maxima of fluorescence emission spectra being pH-dependent. The reverse E → Z photoisomerization predicted by quantum chemistry calculations as energetically favorable for the monoanionic form of furocoumarinic acid was proved in the experiment while being complicated by pyrone ring closure back to psoralen in acidic and neutral conditions. The preparative synthesis of furocoumarinic acid outlined in this work is particularly valuable in view of a wide range of pharmacological effects previously predicted for this compound.

Растворы фотоокисленного псоралена обладают целым рядом биологических эффектов, механизм реализации которых предполагает участие в них гидропероксидов. В настоящей работе содержание гидропероксидов в растворах фотоокисленного псоралена оценивали фотометрически методом FOX-анализа (от англ. Ferrous Oxidation + Xylenol Orange). В экспериментах использовали модифицированный FOX-реагент, с 10-кратным содержанием ксиленолового оранжевого, позволяющий количественно обнаруживать в водной фазе до 50 мкМ гидропероксидов. В процессе фотоокисления 0.1 мМ раствора псоралена в фосфатном буферном растворе продукция гидропероксидов растет с увеличением дозы УФ-А-облучения (~2.5 мкМ экв. H2O2 для дозы 252 кДж/м2 и ~11 мкМ экв. H2O2 для дозы 1512 кДж/м2) и достигает ~16.5 мкМ экв. H2O2 в случае максимальной исследованной дозы облучения (3024 кДж/м2). Сравнение кинетики фотолиза псоралена и формирования гидропероксидов позволяет сделать вывод, что генерация гидропероксидов является результатом вторичных фотохимических процессов с участием фотопродуктов псоралена, предположительно, фотоиндуцированного автоокисления фотопродуктов псоралена альдегидной природы.