Asymmetric synergy between chiral dienes and diphosphines in cationic Rh(I)-catalyzed intramolecular [4 + 2] cycloaddition.

High enantioselective [4 + 2] cycloaddition can be achieved by cationic Rh complexes bearing not only chiral phosphine but also chiral diene. This is the first example of asymmetric synergy between chiral dienes and diphosphines.

Trunk rotation torques through the hip joints during the one- and two-handed backhand tennis strokes.

The aim of the present study was to compare kinetically the roles of the lower extremities in generating trunk rotation in the tennis one-handed and two-handed backhand strokes. Fourteen male collegiate tennis players, seven with a preference for the one- and seven with a preference for the two-handed technique, were recruited as participants. The motion of each backhand stroke was filmed using two high-speed cine-cameras, and the ground reaction forces on the feet were measured separately using two force platforms to determine the joint moments and joint reaction forces at the hip, knee and ankle joints.