The high diastereoselectivity achieved in Strecker synthesis using inexpensive α-phenylglycinol as chiral auxiliary and its facile removal by oxidative cleavage make it an ideal choice for the large scale preparations of optically active α-aminoacids specially α-arylglycines present abundantly in glycopeptide antibiotics. A number of chiral amino acids are synthesized following this method. Also molecular
作者:Yolanda Pérez-Fuertes、James E. Taylor、David A. Tickell、Mary F. Mahon、Steven D. Bull、Tony D. James
DOI:10.1021/jo200528s
日期:2011.8.5
A practically simple three-component Strecker reaction for the asymmetric synthesis of enantiopure alpha-arylglycines has been developed. Addition of a range of aryl-aldehydes to a solution of sodium cyanide and (S)-1-(4-methoxyphenyl)ethylamine affords highly crystalline (S,S)-alpha-aminonitriles that are easily obtained in diastereomerically pure form. Heating the resultant (S,S)-alpha-aminonitriles in 6 M aqueous HCl at reflux resulted in cleavage of their chiral auxiliary fragments and concomitant hydrolysis of their nitrile groups to afford enantiopure (S)-alpha-arylglycines. The enantiopurities of these (S)-a-arylglycines were determined via derivatization of their corresponding methyl esters with 2-formylphenylboronic acid and (S)-BINOL, followed by H-1 NMR spectroscopic analysis of the resultant mixtures of diastereomeric iminoboronate esters.
Diastereoselective strecker synthesis using α-phenylglycinol as chiral auxiliary
作者:T.K. Chakraborty、G.V. Reddy、K. Azhar Hussain
DOI:10.1016/0040-4039(91)80544-g
日期:1991.12
Use of alpha-phenylglycinol as chiral auxiliary in Strecker synthesis ensures high diastereoselectivity and its easy removal by oxidative cleavage allows large scale preparation of optically active alpha-amino acids.