Asymmetric organocatalytic synthesis of tertiary azomethyl alcohols: key intermediates towards azoxy compounds and α-hydroxy-β-amino estersElectronic supplementary information (ESI) available: NMR spectra for new compounds and HPLC traces. See DOI: 10.1039/c7ob00308k

• Main Authors: Carmona, José A, Gonzalo, Gonzalo de, Serrano, Inmaculada, Crespo-Peña, Ana M, Šimek, Michal, Monge, David, Fernández, Rosario, Lassaletta, José M
• Format: Article
• Language: English
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/c7ob00308k

A series of peracylated glycosamine-derived thioureas have been synthesized and their behavior as bifunctional organocatalysts has been tested in the enantioselective nucleophilic addition of formaldehyde tert -butyl hydrazone to aliphatic α-keto esters for the synthesis of tertiary azomethyl alcohols. Using the 1,3,4,6-tetra- O -acetyl-2-amino-2-deoxy-β- d -glucosamine derived 3,5-bis-(trifluoromethyl)phenyl thiourea the reaction could be accomplished with high yields (75-98%) and moderate enantioselectivities (50-64% ee). Subsequent high-yielding and racemization-free tranformations of both aromatic- and aliphatic-substituted diazene products in a one pot fashion provide a direct entry to valuable azoxy compounds and α-hydroxy-β-amino esters. New carbohydrate based organocatalysts have been developed for the asymmetric nucleophilic addition of formaldehyde tert -butylhydrazone to α-keto esters.