The mechanism of the enantioselective addition of diethylzinc to N-(diphenylphosphinoyl)benzalimine with catalysis by bicyclic 2-azanorbornyl-3-methanols was studied by quantum chemical calculations. The mechanism proved to differ from that of the addition of diethylzinc to aldehydes and also from an earlier proposed mechanism. The results of the calculations were used to identify several factors responsible for the selectivity. The theoretical evaluation was performed in connection with an experimental study of the effects of introducing an additional stereocenter in the ligand. An efficient route to both diastereomers of new bicyclic 2-azanorbornyl-3-methanols with an additional chiral center (the secondary alcohol group) is also presented. In the best case, an enantiomeric excess of up to 97 % was obtained with these new ligands.

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