Palladium-Catalyzed Asymmetric [3 + 2] Cycloaddition of 5-Vinyloxazolidinones with Imines Using Chiral Ammonium-Phosphine Hybrid Ligand
摘要:
A palladium-catalyzed asymmetric [3 + 2] annulation reaction between racemic 5-vinyloxazolidinones and N-sulfonyl imines was established. Under the influence of the palladium complex with a chiral ammonium-phosphine hybrid ligand, the cycloaddition proceeded smoothly to yield imidazolidines bearing alpha-amino quaternary stereocenters in high yields with excellent diastereo- and enantioselectivities.
An organocatalytic approach to stereoselective synthesis of 2-hydroxyazetidines and 2-hydroxypyrrolidines
作者:Ankita Rai、Lal Dhar S. Yadav
DOI:10.1016/j.tetlet.2013.04.013
日期:2013.6
A straightforward asymmetric synthesis of a new series of 2-hydroxyazetidines/2-hydroxypyrrolidines with excellent diastereoselectivity was developed via enamine catalysis using diphenylprolinol silyl ether. The Mannich-typereaction of chiral enamines with various aldimines/aziridines under mild conditions followed by intramolecular hemiaminalization affords the desired products 2-hydroxyazetidines