223473-34-5Relevant academic research and scientific papers
A theoretical and experimental study of the asymmetric addition of dialkylzinc to N-(diphenylphosphinoyl)benzalimine
Brandt, Peter,Hedberg, Christian,Lawonn, Klaus,Pinho, Pedro,Andersson, Pher G.
, p. 1692 - 1699 (2007/10/03)
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.
New expedient route to both enantiomers of nonproteinogenic α-amino acid derivatives from the unsaturated 2-aza-bicyclo moiety
Alonso, Diego A.,Bertilsson, Sophie K.,Johnsson, Sandra Y.,Nordin, Sofia J. M.,Soedergren, Mikael J.,Andersson, Pher G.
, p. 2276 - 2280 (2007/10/03)
The influence of the reaction conditions on the catalytic hydrogenation of 2-aza-bicyclo hept-5-ene and oct-5-ene derivatives has been investigated. We found it possible to fully control the extent of allylic vs benzylic C-N hydrogenolysis by simple variations of H2 pressure and acidity of the reaction medium. The use of the reaction pathways was demonstrated by the selective preparation of four categories of optically active α-amino acid derivatives. The strategy was also extended to the synthesis of enantiopure α-amino ketones.
