Hydrogen coordination and

If high chloride concentrations are present in these reactions, the selectivity of the second step is strongly increased for the formation of C-Cl bonds, and P-hydride elimination is inhibited. This effect seems to originate from the saturation of the Pd coordination sites by the Cl and consequent inhibition of hydrogen coordination and thus prevention of the ehmination reactions [108]. The observation that the use of Pd pyridine complexes favored chlorination even at lower chloride concentrations gave rise to an asymmetric chlorohydrin synthesis from allyl ether 154 with the use of chiral bimetallic Pd complex 156 (Scheme 16.42). 

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