title: A diastereo- and enantioselective synthesis of alpha-substituted syn-alpha,beta-diamino acids.
abstract: Highly diastereo- and enantioselective additions of substituted alpha-nitroesters to imines have been developed. High diastereoselection relies on the finding that the combination of chiral proton catalyst 2b and alpha-nitro aryl esters bearing 2,6-disubstitution combine to raise substrate-controlled diastereoselection to >20:1 in favor of the syn diastereomer. Furthermore, the chiral catalyst provides enantioselection to the 99% level through control of the addition step in which the azomethine pi-faces are differentiated. The bifunctional chiral protic acid catalyst enables these reactions to proceed without separate preactivation of either substrate, leading to a straightforward synthetic protocol for the formation of alpha,beta-diamino phenyl alanine derivatives.
authors.affiliation: Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235-1822, USA.
authors.forename: Anand
authors.initials: A
authors.lastname: Singh
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Johnston
mesh_terms: D000085:Acetates / Q000737:chemistry; D000599:Amino Acids, Diamino / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D007097:Imines / Q000737:chemistry; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000138:chemical synthesis; D013237:Stereoisomerism
chemical_list: D000085:Acetates; D000599:Amino Acids, Diamino; D007097:Imines; D010649:Phenylalanine; C028257:nitroacetic acid