High-Throughput Synthesis and Analysis of Acylated Cyanohydrins

The yields and optical purities of products obtained from chiral Lewis acid/Lewis base‐catalysed additions of α‐ketonitriles to prochiral aldehydes could be accurately determined by an enzymatic method. The amount of remaining aldehyde was determined after its reduction to an alcohol, whilst the two product enantiomers were analysed after subsequent hydrolysis first by the (S)‐selective Candida antarctica lipase B and then by the unselective pig liver esterase. The method could be used for analysis of products obtained from a number of aromatic aldehydes and aliphatic ketonitriles. Microreactor technology was successfully combined with high‐throughput analysis for efficient catalyst optimization. Efficient screening of chiral catalysts: The yields and optical purities of O‐acylated cyanohydrin reaction products obtained from a library of chiral catalysts were analysed by a three‐step screening method. By combining enzymatic determination with microreactor technology an efficient system for high‐throughput screening of chiral catalysts was achieved.