Synthesis of Enantiomerically Pure α-Hydroxyaldehydes from the Corresponding α-Hydroxycarboxylic Acids: Novel Substrates for Escherichia coli Transketolase.

Enantiomerically pure (R)-α-hydroxyaldehydes (>95% ee) are prepared from the corresponding α-hydroxyesters by silyl protection, reduction with diisobutylaluminium hydride, and finally deprotection under acidic conditions; subsequent coupling of these aldehydes with lithium hydroxypyruvate, catalysed by Escherichia coli transketolase, leads to novel optically pure triols.