Tips to avoid Aromatic Dechlorination during Catalytic Reduction

At the AMRI Symposium held last month there were some interesting comments made by David Ennis of AstraZeneca during his presentation about a reductive amination step.  The step in question is shown below:

The main side reaction during this chemistry is hydrodechlorination giving, of course, a des-chloro impurity.  Catalyst supplier Johnson Matthey advised that Pt/C catalysts usually give lower levels of des-chloro impurities than Pd/C and also recommended the addition of a catalytic amount of DMSO to minimise hydrodechlorination.

David Ennis (AstraZeneca) presentation at the AMRI Chemical Development Symposium, October, 2011, Albany NY.