Synthesis of α-hydroxyhydrazones from aldehydes

Article abstract of DOI:10.1055/s-2001-15139

The 1,2-addition of formaldehyde N,N-dialkylhydrazones to simple aldehydes takes place in the presence of ZnCl₂ or Et₂AlCl to afford the corresponding α-hydroxyhydrazones. More reactive aldehydes undergo addition of these reagents in the absence of promoters. Use of (S)-1-methyleneamino-2-(diphenylmethoxymethyl) pyrrolidine as the reagent afforded separable mixtures of diastereoisomers, thereby allowing for the isolation of optically pure adducts in a single step.