A method for the preparation of a functionalized conjugated diene selected from the group of compounds of formula (IIIa), (IIIb), (IIIc) wherein - R is an organylene group optionally containing one or more heteroatoms selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a silicon atom, and the starting conjugated diene selected from the group of compounds of formula (Ia), (lb), (Ic) from which the functionalized conjugated diene of formula (IIIa), (IIIb), (IIIc) is derived, has at least 10 carbon atoms, - R 1 is selected from i) a single bond, ii) one or more of an oxygen atom, a sulfur atom, a group NR 6, and a group SiR 7 R 8; and iii) an organylene group optionally containing one or more selected from an oxygen atom, a sulfur atom, a group NR 6, and a group SiR 7 R 8; - R 2, R 3, R 6, R 7, R 8 can be the same or different and represent an organyl group optionally containing one or more heteroatoms selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a silicon atom; and i) R 4 and R 5 can be the same or different and each R 4 and R 5 independently represents an organyl group optionally containing one or more heteroatoms selected from a silicon atom, an oxygen atom, a sulfur atom, and a nitrogen atom; or ii) R 4 and R 5 are bonded to each other to form a heterocyclic ring containing the nitrogen atom and at least one carbon atom and, optionally, one or more heteroatoms selected from a silicon atom, an oxygen atom, a sulfur atom, and a nitrogen atom, the method comprising reacting, under Grignard conditions, a conjugated diene halide selected from the group of compounds of formula (IIa), (IIb), (IIc) wherein Y 1 is selected from fluorine, chlorine, bromine, and iodine atoms (and Y 1 is preferably a chlorine atom), with a compound of formula wherein Y 2 is selected from fluorine, chlorine, bromine, and iodine atoms. - R is an organylene group optionally containing one or more heteroatoms selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a silicon atom, and the starting conjugated diene selected from the group of compounds of formula (Ia), (lb), (Ic) from which the functionalized conjugated diene of formula (IIIa), (IIIb), (IIIc) is derived, has at least 10 carbon atoms, - R 1 is selected from i) a single bond, ii) one or more of an oxygen atom, a sulfur atom, a group NR 6, and a group SiR 7 R 8; and iii) an organylene group optionally containing one or more selected from an oxygen atom, a sulfur atom, a group NR 6, and a group SiR 7 R 8; i) a single bond, ii) one or more of an oxygen atom, a sulfur atom, a group NR 6, and a group SiR 7 R 8; and iii) an organylene group optionally containing one or more selected from an oxygen atom, a sulfur atom, a group NR 6, and a group SiR 7 R 8; - R 2, R 3, R 6, R 7, R 8 can be the same or different and represent an organyl group optionally containing one or more heteroatoms selected from an oxygen atom, a sulfur atom, a nitrogen atom, and a silicon atom; and i) R 4 and R 5 can be the same or different and each R 4 and R 5 independently represents an organyl group optionally containing one or more heteroatoms selected from a silicon atom, an oxygen atom, a sulfur atom, and a nitrogen atom; or ii) R 4 and R 5 are bonded to each other to form a heterocyclic ring containing the nitrogen atom and at least one carbon atom and, optionally, one or more heteroatoms selected from a silicon atom, an oxygen atom, a sulfur atom, and a nitrogen atom, the method comprising reacting, under Grignard conditions, a conjugated diene halide selected from the group of compounds of formula (IIa), (IIb), (IIc) wherein Y 1 is selected from fluorine, chlorine, bromine, and iodine atoms (and Y 1 is preferably a chlorine atom), with a compound of formula wherein Y 2 is selected from fluorine, chlorine, bromine, and iodine atoms. i) R 4 and R 5 can be the same or different and each R 4 and R 5 independently represents an organyl group optionally containing one or more heteroatoms selected from a silicon atom, an oxygen atom, a sulfur atom, and a nitrogen atom; or ii) R 4 and R 5 are bonded to each other to form a heterocyclic ring containing the nitrogen atom and at least one carbon atom and, optionally, one or more heteroatoms selected from a silicon atom, an oxygen atom, a sulfur atom, and a nitrogen atom,