METHOD OF PRODUCING CARBOXANILIDES OR THEIR AMMONIUM SALTS

A new process for the preparation of 6-deoxyanthracyclinones of general formula I: I wherein R represents a hydrogen atom, a hydroxy group or a lower alkoxy group is described. The process provides a total synthesis of the 6-deoxyanthracyclinones of formula I using 1,2,3,6-tetrahydro-phthalate as starting material. The obtained racemic mixture of the compounds of formula I, if desired, can be submitted to optical resolution by the conventional method of conversion to diastereomeric derivatives using a chiral resolving agent. Alternatively, the racemic mixture can be used as such for the condensation with a suitably protected halosugar derivative to obtain alpha glycosidic derivatives of formula XV: XV wherein R1 represents a hydrogen atom or a hydroxy group, one of R2 and R3 represents a hydrogen atom, the other of R2 and R3 represents a hydrogen atom or a hydroxy group and X is a hydrogen atom or a trifluoro acetyl group. The N-trifluoroacetyl 7S:9S and 7R:9R derivatives of the alpha -glycosides of formula XV can be separated by chromatography on silica gel to obtain, after mild alkaline hydrolisis the wanted 7S:9S alpha -glycosides (R1=H) as free bases and can eventually be transformed into their corresponding doxorubicin derivatives (R1=OH) by known procedures.