Cu(I)-carbenoid- and Ag(I)-Lewis acid-catalyzed asymmetric intermolecular insertion of alpha-diazo compounds into N-H bonds.
Chiral Cu(I)-bisoxazoline- and Cu(I)-PN-complexes were found to catalyze the intermolecular insertion of alpha-diazo compounds into N-H bonds. The insertion reactions proceed with enantioselectivities of up to 28% ee for the different alpha-diazo acetates into one of the N-H bonds of different amines. Analogous chiral Ag(I) complexes were found to give higher enantioselectivities of up to 48% ee, however, lower yields were obtained. There are indications, that the Ag(I)-mediated reactions follow a different reaction mechanism compared to the Cu(I)-catalyzed insertions. It is demonstrated that different alpha-amino acid derivatives can be obtained via this approach in good yields and with low to moderate enantioselectivities. However, the results obtained are the highest asymmetric inductions obtained for an intermolecular N-H insertion via chiral carbene complexes or chiral Lewis acid catalysis.
Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus University, Aarhus, Denmark.
Stephan
S
Bachmann
Doris
D
Fielenbach
Karl Anker
KA
Jorgensen
D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D015394:Molecular Structure; D018030:Silver Compounds / Q000737:chemistry*
D018030:Silver Compounds; D003300:Copper