Asymmetric synthesis of α- and β-amino acids by diastereoselective addition of triorganozincates to N-(tert-butanesulfinyl)imines

The diastereoselective addition of triorganozincates to (R)-N-(tert-butanesulfinyl)imines has been used as a key step to achieve the synthesis of highly enantiomerically enriched N-protected alpha- and beta-amino acids. Desulfinylation of the addition products followed by benzoylation of the nitrogen atom of the obtained primary amines and oxidation of one of the substituents on the carbon atom connected to the nitrogen complete the sequence. Using the same configuration in the sulfinyl chiral auxiliary, alpha-amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. alpha,alpha-Disubstituted alpha-amino esters with high enantiomeric purity can also be prepared when a-imino esters are the starting substrates. (C) 2010 Elsevier Ltd. All rights reserved.