Racemic Ketones and Chiral Non-Enzymatic Hydride Donors

Racemic Ketones and Chiral Non-Enzymatic Hydride Donors 

In more complicated situations, small discrepancies in product assay are very difficult to avoid, and they may also be difficult to interpret. Reactions taken to partial conversion can be especially confusing because the product ratios will vary if the starting enantiomers react at different rates (simple KR). If the composition of unreacted starting material is not taken into account using Equation 6.1, then the product ratios can be misleading. Even in examples where reactants and 

In a separate experiment, oxazaborolidine catalyst ent-33 (15%) was used to effect the reduction of rac-36 with a larger amount of borane (0.9 mol equiv vs 0.6 mol equiv) and conversion was taken to 100% over 80 min. In this case, a diastereomer ratio of 2.4 1 was obtained, and 37 and 38 were isolated with enantiomeric excesses of 36% and 89%, respectively [20]. These results are in good agreement with Equation 6.2 and provide a better idea of the preparative potential of stereodivergent RRM in the acetylated cyclophanes. 

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