Asymmetric chiral poisoning method

Another interesting issue is the possibility of creating optically active compounds with racemic catalysts. The term chiral poisoning has been coined for the situation where a chiral substance deactivates one enantiomer of a racemic catalyst. Enantiomerically pure (R,R)-chiraphos rhodium complex affords the (iS )-methylsuccinate in more than 98% ee when applied in the asymmetric hydrogenation of a substrate itaconate.109 An economical and convenient method... 

Although [Mo]-II was the only effective chiral catalyst available in the early 2000s,molybdenum-based catalysts prepared from easy-to-handle precursors by in situ methods have led to a significantly efficient asymmetric catalyst. For example, [Mo]-III (5mol%) exerted the efficiency on the ARCM reaction of 151 (83% yield, 87% ee) in an enantioselective synthesis of coniine (153, Scheme 24.39), a poisonous alkaloid found in poison hemlock and the yellow pitcher plant. [Mo]-II can be considered as a first-choice catalyst for the ARCM reaction as a result of its commercial availability, and it has been used in recent synthesis of natural product. 

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