A process for preparation of a compound of formula wherein each R 1 and R 2 are independently C 1 -C 4 alkyl; R 3 is selected from the group consisting of hydrogen and C 1 -C 4 alkyl; said process comprising reacting a compound of formula wherein X is selected from the group consisting of Br, Cl, CF 3 SO 3 -, CH 3 C 6 H 4 SO 3 - and CH 3 SO 3 -, and R 1, R 2 and R 3 are as defined herein, with a compound of formula the reaction being carried out in the presence of a π-allylpalladium complex; and a phosphine ligand of the formula or a suitable salt thereof, wherein R 4 is selected from the group consisting of C 1 -C 6 alkyl, C 5 -C 6 cycloalkyl, phenyl and heteroaryl, wherein the heteroaryl is a 5- or 6-membered aromatic ring which comprises 1 or 2 heteroatoms independently selected from N and O, and wherein the phenyl or heteroaryl are optionally substituted by 1, 2, 3, 4 or 5 R 5 substituents, which may be the same or different; R 5 is selected from the group consisting of halogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino, N,N-diC 1 -C 4 alkylamino and phenyl, wherein said phenyl is optionally substituted by 1, 2, 3 or 4 R 6 substituents, which may be the same or different; R 6 is selected from the group consisting of C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino and N,N-diC 1 -C 4 alkylamino; and a base. each R 1 and R 2 are independently C 1 -C 4 alkyl; R 3 is selected from the group consisting of hydrogen and C 1 -C 4 alkyl; said process comprising reacting a compound of formula wherein X is selected from the group consisting of Br, Cl, CF 3 SO 3 -, CH 3 C 6 H 4 SO 3 - and CH 3 SO 3 -, and R 1, R 2 and R 3 are as defined herein, with a compound of formula the reaction being carried out in the presence of a π-allylpalladium complex; and a phosphine ligand of the formula or a suitable salt thereof, wherein R 4 is selected from the group consisting of C 1 -C 6 alkyl, C 5 -C 6 cycloalkyl, phenyl and heteroaryl, wherein the heteroaryl is a 5- or 6-membered aromatic ring which comprises 1 or 2 heteroatoms independently selected from N and O, and wherein the phenyl or heteroaryl are optionally substituted by 1, 2, 3, 4 or 5 R 5 substituents, which may be the same or different; R 5 is selected from the group consisting of halogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino, N,N-diC 1 -C 4 alkylamino and phenyl, wherein said phenyl is optionally substituted by 1, 2, 3 or 4 R 6 substituents, which may be the same or different; R 6 is selected from the group consisting of C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino and N,N-diC 1 -C 4 alkylamino; and a base. X is selected from the group consisting of Br, Cl, CF 3 SO 3 -, CH 3 C 6 H 4 SO 3 - and CH 3 SO 3 -, and R 1, R 2 and R 3 are as defined herein, with a compound of formula the reaction being carried out in the presence of a π-allylpalladium complex; and a phosphine ligand of the formula or a suitable salt thereof, wherein R 4 is selected from the group consisting of C 1 -C 6 alkyl, C 5 -C 6 cycloalkyl, phenyl and heteroaryl, wherein the heteroaryl is a 5- or 6-membered aromatic ring which comprises 1 or 2 heteroatoms independently selected from N and O, and wherein the phenyl or heteroaryl are optionally substituted by 1, 2, 3, 4 or 5 R 5 substituents, which may be the same or different; R 5 is selected from the group consisting of halogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino, N,N-diC 1 -C 4 alkylamino and phenyl, wherein said phenyl is optionally substituted by 1, 2, 3 or 4 R 6 substituents, which may be the same or different; R 6 is selected from the group consisting of C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino and N,N-diC 1 -C 4 alkylamino; and a base. wherein R 4 is selected from the group consisting of C 1 -C 6 alkyl, C 5 -C 6 cycloalkyl, phenyl and heteroaryl, wherein the heteroaryl is a 5- or 6-membered aromatic ring which comprises 1 or 2 heteroatoms independently selected from N and O, and wherein the phenyl or heteroaryl are optionally substituted by 1, 2, 3, 4 or 5 R 5 substituents, which may be the same or different; R 5 is selected from the group consisting of halogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino, N,N-diC 1 -C 4 alkylamino and phenyl, wherein said phenyl is optionally substituted by 1, 2, 3 or 4 R 6 substituents, which may be the same or different; R 6 is selected from the group consisting of C 1 -C 4 alkyl, C 1 -C 4 alkoxy, N-C 1 -C 4 alkylamino and N,N-diC 1 -C 4 alkylamino; and a base.