Asymmetric synthesis of α-amino carbonyl derivatives using lithium (R)-N-benzyl-N-α-methylbenzylamide
Davies SG., Epstein SW., Garner AC., Ichihara O., Smith AD.
An efficient protocol for the transformation of homochiral α-hydroxy-β-amino esters to their α-amino carbonyl components is presented. Diastereoselective conjugate addition of lithium (R)-N-benzyl-N-α-methylbenzylamide to a range of α,β-unsaturated esters and subsequent enolate hydroxylation with (1R)-(-)-(camphorsulfonyl)oxaziridine, followed by LiAlH4 reduction produces homochiral 3-amino 1,2-diols. Subsequent oxidative cleavage with H5IO6 provides N-benzyl-N-α-methylbenzyl protected α-amino aldehydes (96-98% d.e.) and ketones (88% d.e.). Further oxidation of the α-amino aldehydes with sodium chlorite and Pd-catalysed hydrogenation provides α-amino acids in 94-98% e.e. © 2002 Elsevier Science Ltd. All rights reserved.