Pyrrolidinopyridines in Palladium-Catalyzed Allylic Substitutions − Conformation of the Ligand
摘要:
The (R,R)-2-[(2,5-dimethylpyrrolidin-1-yl)methyl]pyridines 4, 5, and 6 carrying a 2-hydroxyalkyl, 2-alkoxyalkyl or 2-siloxyalkyl substituent in the 6-position of the pyridine ring were prepared and assessed in palladium-catalyzed allylations of 1,3-diphenylpropenyl acetate with malonate. All ligands having g-substituents with an S absolute configuration afforded the product with an R configuration in 80-84% ee, whereas those having substituents with an R absolute configuration gave the opposite product with a selectivity depending on the nature of the substituent (8-74% ee). It is believed that the enantioselectivity is dependent on the conformation of that substituent.
Pyrrolidinopyridines in Palladium-Catalyzed Allylic Substitutions − Conformation of the Ligand
摘要:
The (R,R)-2-[(2,5-dimethylpyrrolidin-1-yl)methyl]pyridines 4, 5, and 6 carrying a 2-hydroxyalkyl, 2-alkoxyalkyl or 2-siloxyalkyl substituent in the 6-position of the pyridine ring were prepared and assessed in palladium-catalyzed allylations of 1,3-diphenylpropenyl acetate with malonate. All ligands having g-substituents with an S absolute configuration afforded the product with an R configuration in 80-84% ee, whereas those having substituents with an R absolute configuration gave the opposite product with a selectivity depending on the nature of the substituent (8-74% ee). It is believed that the enantioselectivity is dependent on the conformation of that substituent.
The (R,R)-2-[(2,5-dimethylpyrrolidin-1-yl)methyl]pyridines 4, 5, and 6 carrying a 2-hydroxyalkyl, 2-alkoxyalkyl or 2-siloxyalkyl substituent in the 6-position of the pyridine ring were prepared and assessed in palladium-catalyzed allylations of 1,3-diphenylpropenyl acetate with malonate. All ligands having g-substituents with an S absolute configuration afforded the product with an R configuration in 80-84% ee, whereas those having substituents with an R absolute configuration gave the opposite product with a selectivity depending on the nature of the substituent (8-74% ee). It is believed that the enantioselectivity is dependent on the conformation of that substituent.