Patent ID: 7323589

Claim:
A method for synthesizing a compound of formula (1) having n+1 units from a compound of formula (1) having n units wherein G represents a —NR 4 R 5 group where R 4 and R 5 , which are identical or different, are each a linear or branched alkyl group of 1 to 5 carbon atoms, or a cycloalkyl group of 3 to 7 carbon atoms, or R 4 and R 5 together with the nitrogen atom carrying them form a ring, R 1 represents a hydrogen atom or a linear or branched alkyl group of 1 to 5 carbon atoms, n is an integer equal to 1 or 2, R 2 and R 3 represent identical or different substituent in each unsaturated unit, successive unsaturated units being identical or different, R 2 and R 3 being hydrogen or a linear or branched alkyl group of 1 to 5 carbon atoms, and provided that at least one of the substituents R 1 , R 2 and R 3 is different from hydrogen, and Y 1 and Y 2 each represent a —COOR 7 group where R 7 is an alkyl group of 1 to 5 carbon atoms, comprising reacting an organometallic in a solvent with the compound of formula (1) having n units to obtain a compound of formula (3) in which R 1 , R 2 and R 3 , Y 1 and Y 2 are as defined above and R represents a corresponding alkyl group of 1 or 2 carbon atoms, and treating the compound of formula (3) with a protected form of N,N-dimethylformamide or with N,N-dimethylacetamide dimethyl acetal.