A novel and efficient asymmetric synthesis of carbon‐14 labeled ( S , S )‐2,7‐di‐boc‐diamino[1,8‐ 14 C 2 ]suberic acid

Five hundred mCi of Potassium [ 14 C]cyanide at a specific activity of 51 mCi/mmol was used to diastereoselectively introduce the carbon‐14 label into 1,6‐hexanedial via a thermodynamically controlled asymmetric Strecker reaction using ( R )‐(‐)‐2‐phenylglycinol as the chiral auxiliary. The expected and predominant ( R , S / S , R ) diastereomer ( 2 ) was separated by preparative normal phase HPLC. The chiral auxiliary was removed by oxidation with lead tetraacetate and the resulting benzylimino nitrile exhaustively hydrolyzed in hydrochloric acid to give ( S , S )‐2,7‐diamino[1,8‐ 14 C 2 ]suberic acid ( 6 ). Subsequent acylation with di‐tert‐butyldicarbonate gave the title compound ( 1 ) with a radiochemical purity of 95.5%, a specific activity of 113 mCi/mmol, and an enantiomeric purity of 95.5% e.e. To our knowledge this is the first report of the asymmetric Strecker methodology being applied to the synthesis of a carbon‐14 labeled amino acid. Copyright © 2002 John Wiley & Sons, Ltd.