Patent ID: 7250536

Claim:
A process for the isomerisation of a substrate of formula wherein each R 1 represents, simultaneously or independently, a hydrogen atom or a methyl group and R 2 represents a hydrogen atom linear or branched C 1-4 alkyl or a C 2-5 1-alkenyl group; into a mixture comprising at least one compound of formula (II) and at least one compound of formula (II′) wherein R 1 R 2 have the same meaning as indicated above; said process being carried out in a non-coordinating or weakly coordinating medium, under an inert atmosphere and in the presence of a catalyst obtained by the reaction of a) a ruthenium precursor of the formula [Ru(diene)(allyl) 2 ], [Ru(dienyl) 2 ], [Ru(tetraene)(ene)] or [Ru(diene)(triene)]; and b) a protic acid of formula HX, wherein X is a weakly-or non-coordinating anion; or a Lewis acid of formula B(R 3 ) 3 , wherein R 3 represents a fluoride or a phenyl group optionally substituted by one to five groups such as halide atoms or methyl or CF 3 groups, or a Lewis acid of formula FeX 3 , FeX 2 , AgX, AlY 3 , FeY 3 , FeY 2 , SnY 2 , SnY 4 , AgY, AgY 2 , SbY 5 , AsY 5 or PY 5 , X being a group as defined above arid Y being a fluorine or chlorine atom; in a non-coordinating or weakly coordinating medium and under an inert atmosphere, the molar ratio acid/ruthenium being comprised between 0.3 and 3.1.