Four new chiral aminodiols 1-4, which were prepared from methyl L proline in 2 steps, were applied in the enantioselective addition of diethylzinc to benzaldehyde. The results indicated that the enantioselectivities e...Four new chiral aminodiols 1-4, which were prepared from methyl L proline in 2 steps, were applied in the enantioselective addition of diethylzinc to benzaldehyde. The results indicated that the enantioselectivities enhance with increasing the bulkiness of substituents on chiral ligands and with chiral ligand 4 giving the best result. When ligand 4 was used to catalyze the enantioselective addition of diethylzinc to aromatic aldehydes, the substituents affect the enantioselectivities slightly and 1 naphthaldehyde gives the best enantiomeric excess(up to 75.3% ). On the other hand, 4 (dimethylamino)benzaldehyde gives a low enantiomeric excess, which may most likely arise from a non steroselective ethyl transfer to aldehyde promoted by zinc coordination of amino group. For aliphatic aldehydes, poor enantiomeric excesses are generally given.展开更多
A new ligand,3,6-bis（9-O-quinidine）pyridazine（（QD）2PYDZ）,was synthesized from quinidine and 3,6-dichloropyridazine under mild condition.It can be purified by recrystallization to give the yield of 73%.The use of...A new ligand,3,6-bis（9-O-quinidine）pyridazine（（QD）2PYDZ）,was synthesized from quinidine and 3,6-dichloropyridazine under mild condition.It can be purified by recrystallization to give the yield of 73%.The use of（QD）2 PYDZ in asymmetric dihydroxylation（AD）of olelfins provided the corresponding chiral vicinal diols with 88～95%chemical yield and the values of enantiomeric excess（ess）are between 75% and 99%.Meanwhile,chiral β-amino alcohols with excellent eantioselectivity and regioselectivity were also achieved when the asymmetric aminohydroxylation（AA）of olefins were catalyzed by the complex（QD）2PYDZ-Os04.Their chemical yields ranged from 52%to 63%.In addition,during the AD reaction of ethyl trans-cinnamate,（QD）2PYDZ can be recovered and reused for five runs without any signilficant loss in its catalytlc efficiency.展开更多
文摘Four new chiral aminodiols 1-4, which were prepared from methyl L proline in 2 steps, were applied in the enantioselective addition of diethylzinc to benzaldehyde. The results indicated that the enantioselectivities enhance with increasing the bulkiness of substituents on chiral ligands and with chiral ligand 4 giving the best result. When ligand 4 was used to catalyze the enantioselective addition of diethylzinc to aromatic aldehydes, the substituents affect the enantioselectivities slightly and 1 naphthaldehyde gives the best enantiomeric excess(up to 75.3% ). On the other hand, 4 (dimethylamino)benzaldehyde gives a low enantiomeric excess, which may most likely arise from a non steroselective ethyl transfer to aldehyde promoted by zinc coordination of amino group. For aliphatic aldehydes, poor enantiomeric excesses are generally given.
文摘A new ligand,3,6-bis（9-O-quinidine）pyridazine（（QD）2PYDZ）,was synthesized from quinidine and 3,6-dichloropyridazine under mild condition.It can be purified by recrystallization to give the yield of 73%.The use of（QD）2 PYDZ in asymmetric dihydroxylation（AD）of olelfins provided the corresponding chiral vicinal diols with 88～95%chemical yield and the values of enantiomeric excess（ess）are between 75% and 99%.Meanwhile,chiral β-amino alcohols with excellent eantioselectivity and regioselectivity were also achieved when the asymmetric aminohydroxylation（AA）of olefins were catalyzed by the complex（QD）2PYDZ-Os04.Their chemical yields ranged from 52%to 63%.In addition,during the AD reaction of ethyl trans-cinnamate,（QD）2PYDZ can be recovered and reused for five runs without any signilficant loss in its catalytlc efficiency.
