Asymmetric transfer hydrogenation catalytic properties and mechanism

2 Asymmetric transfer hydrogenation catalytic properties and mechanism 

The bis-acetonitrile complexes 55-63 were not active for either TH or DH of acetophenone in /PrOH/KOtBu. However, the monocarbonyl complexes 67, 68, 70 and 73 with the correct steric and electronic properties at phosphorus and nitrogen, as defined in Section 8.3.2.1 were active for TH but not DH as long as they were first activated with KOfBu in /PrOH. The complexes 67 and 73 with bromide and acetonitrile trails to carbonyl provided the same ATH activity and selectivity. The bromide complexes were easiest to prepare and were used for most of the catalyst testing. 

The bis(amine) complex [Fe(Br)(CO)(P-NH-NH-P)]BPh was also synthesized and tested for catalysis, and showed a much lower conversion of only 10% after 2 h. Thus, the ene-amido portion of the active catalyst is critical for superior activity. 

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