Good isomerization of 2-cyclohexenol by two Ru(ii) complexes, synthesis and characterization of a reaction intermediate.

The catalytic activities of [RuClCp(PTA)2] (1) and [RuCp(PTA)2(H2O-κO)]OTf (2) were assessed for the redox isomerization of the cyclic allylic alcohol 2-cyclohexenol into cyclohexanone in water and biphasic media. Complex 2 showed unprecedented good TONs for the studied conversion both in water (TON = 647) and in the biphase of cyclohexene/H2O (TON = 3420) while 1 showed a lower but also good activity (water TON = 95, biphasic TON = 100). The catalytic reaction intermediate [RuCp(PTA)2(η2-C6H9OH)]CF3SO3 (3) was synthesized and characterized using NMR.