| abstract |
The present invention relates to a method for the preparation of compounds having the following formula (I):n nin which: nR 1 , R 2 , R 3 , and R 4 represent, independently from each other, in particular H or an alkyl group having from 1 to 20 carbon atoms, nsaid method comprising the reaction of a compound of formula (II)n nR 1 and R 2 being as defined above, nwith a compound having the following formula (III):n nR 3 and R 4 being as defined above, nin the presence of a catalytic amount of an acid. |