Process for preparing 4-hydroxycoumarin derivatives.

摘要

The invention provides a process for preparing a 4-hydroxycoumarin derivative having anti-coagulant properties, useful as a rodenticide, of formula <CHEM> wherein R<1> and R<2> are independently selected from the group consisting of hydrogen, halogen, alkyl of up to 6 carbon atoms and alkoxy of up to 6 carbon atoms, and R<3> represents a group selected from <CHEM> where X represents a halogen atom or a group C1 12 alkyl, C1 12 alkoxy, C3-8 cycloalkyl, CN, SO2R<5>, CF3, OCF3, COOR<5> or COR<5>, where R<5> is C1 6 alkyl, n min is 0, 1 or 2 and Y is a fluorine or chlorine atom; <CHEM> where n min and Y are as defined above, X is as defined above or is hydrogen, n sec is 0 or 1 and D is an oxygen atom or a group -O-(CH2)m-, -(CH2)m-O-, -O-(CH2)m -O-(CH2)p-, -(CH2)-m, or -CH=CH-, or a sulphur ana logue thereof, wherein m is in the range 1 to 6 and p is in the range 1 to 6; <CHEM> where X, n min and Y are as defined in (a) above. (d) a group selected from <CHEM> and <CHEM> and (e) a group selected from <CHEM> where X and n sec are defined as in (b) above, A is an oxygen or sulphur atom and D min is an oxygen atom or a -CH2- group, which process comprises condensing 4-hydroxycoumarin with a compound of formula <CHEM> or the corresponding 1,2-dihydronaphthalene, wherein R<1>, R<2> and R<3> are as defined above, and L is a hydroxy group or a halogen aotm, in the presence of an organic solvent and a catalyst characterised in that the solvent is selected from formic acid, a mixture of formic acid and at least one C2-6 aliphatic acid having a boiling temperature at atmospheric pressure in the range 60 DEG C to 105 DEG C and a liquid halogenated hydrocarbon having a boiling temperature of at least 60 DEG C, and reaction is effected at a temperature in the range 60 DEG C to the reflux temperature of the reaction mixture.