Study of chemical behaviors of 4-hydroxycumarin in alkali media: dicumarols or dihydro-4H-furo[3,2-c]chromenes?

Dicoumarol: from chemistry to antitumor benefits

“…There are some publications on the synthesis of dicoumarols in the presence of 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) as non-nucleophilic and strong tertiary amine base [30], in phosphoroxychloride in dry DMF [31], in refluxing ethanol and acetic acid [27,[32][33][34][35], under microwave irradiation in ethanol or solvent-free conditions [32], in the presence of diethylaluminum chloride (Et 2 AlCl) in dichloromethane [36], in the presence of catalytic amount of piperidine in ethanol [37] or other polar solvents like methanol, dimethylformamide or dimethyl sulfoxide at room temperature [38], and using triethylamine in methanol or sodium ethoxide in ethanol in the presence of cyanogen bromide [39]. It was also published some uncatalyzed onepot synthesis of dicoumarols under conventional or microwave thermal solvent-free conditions, which is a simple, practical, and environmentally benign method to obtain dicoumarols in excellent yields [30,40,41] as well as the catalyst-free one-pot synthesis in water under ultrasounds irradiation at ambient temperature [42] or the "on solvent" reaction using minimal amount of boiling propanol without any catalyst [43].…”