ES415421A1 - Digitoxin esters - Google Patents

Abstract

Procedure for the preparation of new cardioglycosides of the general formula I **(See formula)** where R1 can mean the group **(See formula)** and R2 can mean a preferably straight chain alcohol radical with 2 to 15 carbon atoms, an alcohol radical with 1 to 4 carbon atoms [preferably in terminal position] substituted by a halogen atom, a nitrile group, a carboethoxy group or an optionally substituted phenyl or phenoxy radical [especially a para-tolyl or para-toloxy radical, a para-methoxyphenyl or para-methoxyphenoxy radical or a para-chlorophenyl or para-chlorophenoxy radical] or a cycloalkyl or cycloalkylmethyl radical with 3 to 6 atoms in the ring or an N-trifluoromethylcarbonylaminoethyl radical, characterized in that a compound of the general formula II **(See formula)** where R1 has the meanings mentioned above, it is subjected to a transesterification reaction with an orthoester of the general formula III wherein R2 has the meanings mentioned above and R means a lower alcohol group, to transform it into a cyclic orthoester of the general formula IV **(See formula)** where R, R1 and R2 have the meanings indicated above, the transesterification reaction being carried out in the presence of acid catalysts, optionally with the addition of an inert solvent to the reaction mixture, and at a temperature comprised between 0ºC and the reflux temperature of the reaction mixture, preferably at around room temperature, and because said orthoester of formula IV is partially saponified in the presence of an aqueous acid. (Machine-translation by Google Translate, not legally binding)