Synthesis of <i>C</i>-Protected α-Amino Aldehydes of High Enantiomeric Excess from Highly Epimerizable <i>N</i>-Protected α-Amino Aldehydes
作者:Andrew G. Myers、Boyu Zhong、Daniel W. Kung、Mohammad Movassaghi、Brian A. Lanman、Soojin Kwon
DOI:10.1021/ol006427s
日期:2000.10.1
[GRAPHICS]A new procedure for the preparation of C-protected alpha-amino aldehydes of high enantiomeric excess is illustrated using five differently substituted alpha-(KFmoc)amino aldehydes as starting materials. Highly epimerization-prone substrates were converted to the corresponding morpholino nitrile-protected alpha-amino aldehydes with minimal racemization (products greater than or equal to 89% ee). Morpholino nitrile derivatives of phenylglycinal were crystallized and subjected to X-ray structural analysis, allowing for definitive determination of the stereochemistry of amino nitrile formation. A rationale for the stereoselectivity of amino nitrile formation is presented.
Observations Concerning the Existence and Reactivity of Free α-Amino Aldehydes as Chemical Intermediates: Evidence for Epimerization-Free Adduct Formation with Various Nucleophiles