Measurement of Enantiomeric Excess by Kinetic Resolution and Mass Spectrometry

New applications for your mass spectrometer—use it to measure enantiomeric excess! The enantiomeric content of very small quantities of chiral alcohols and amines has been determined by derivatization with chiral acylating agents in which mass is correlated to absolute configuration. The resultant esters and amides were then analyzed by electrospray ionization mass spectrometry (ESI‐MS; shown schematically). The technique requires surprisingly low levels of diastereoselectivity in the acylation step, and is therefore generally applicable.