Gold-Free Aldol-Type Additions of α-Isothiocyanato Imides to Aldehydes

Significance

Seidel and co-workers report an organocatalytic diastereo- and enantioselective aldol addition of α-isothiocyanato imides to aldehydes. The reaction is catalyzed by bifunctional thiourea catalyst 1. A sterically demanding substitution on the imide is necessary for high diastereoselectivities and moreover for suppressing the formation of undesired product 2. The applicability was shown by preparing the protected β-hydroxy-α-amino acid 3 on a large scale and reducing the catalyst loading to 1 mol%.