The synthesis of enantiomerically pure C 2-symmetric bis-pyridinium salts was realized through a simple condensation of 2-pyridyl-carboxyaldehydes with a chiral diamine. The catalytic properties of such novel compounds were preliminarily studied and the trifluoracetate salts of chiral bis-imines of 2-picolinaldehydes derivedfrom1,1′-binaphthyl-2,2′-diamine were shown to catalyze the Diels-Alder reaction
Chiral organic catalysts for the enantioselective reduction of n-alkyl and n-benzyl-substituted alicyclic and cyclic imines
申请人:UNIVERSITA' DEGLI STUDI DI MILANO
公开号:EP2166002A1
公开(公告)日:2010-03-24
Chiral organic catalysts of formula (I)
wherein ar, R1 and R2 are as defined in the description are herein disclosed. these catalysts promote the enantioselective reduction of n-alkyl and n-benzyl- substituted alicyclic and cyclic imines in the presence of trichlorosilane, avoiding the use of metal chitalysts or of metal-free catalysts which suffer from stability problems. the invention also relates to the preparation of the catalysts and to a process for the reduction on n-alkyl and n-benzyl substituted alicyclic and cyclic imines in which the imines are prepared in situ.
Highly Stereoselective Metal-Free Catalytic Reduction of Imines: An Easy Entry to Enantiomerically Pure Amines and Natural and Unnatural α-Amino Esters
A highly efficient catalytic stereoselective ketimine reduction is described. The combination of an inexpensive chiral organocatalyst, easily prepared in a single step, and of a very cheap removable chiral auxiliary allowed us to obtain enantiomerically pure amino compounds. The methodology allowed synthesis of chiral secondary and primary amines and natural and unnatural amino esters in high yields often with total control of the absolute stereochemistry.