Chiral Proline Amide-Isothiouronium Salt Spaced with Diamine as an Efficient Bifunctional Organocatalyst for Enantioselective α-Hydrazination of Aldehydes

The chiral proline amide-isothiouronium salt-based bifunctional organocatalyst was prepared by methylating of the corresponding chiral thiourea, containing more acidic and active N-H bonds compared to thiourea. This catalyst was applied to alpha-hydrazination of aldehydes using azodicarboxylates, which can be transformed into beta-hydrazino alcohols, beta-amino alcohols, and alpha-amino acid derivatives. Enantioselective alpha-hydrazination of aldehydes has been successfully carried out with amide-isothiouronium salt as a chiral catalyst. Various hydrazino aldehydes were obtained in high to quantitative yields and excellent enantioselectivities (of up to 99 % ee) in the presence of a benzoic acid additive.

Automated summary

The chiral proline amide-isothiouronium salt-based bifunctional organocatalyst, which has more acidic and active N-H bonds compared to thiourea, was prepared by methylating the corresponding chiral thiourea. This catalyst was used for the alpha-hydrazination of aldehydes using azodicarboxylates to produce beta-hydrazino alcohols, beta-amino alcohols, and alpha-amino acid derivatives. Enantioselective alpha-hydrazination of aldehydes was successfully carried out with the amide-isothiouronium salt as a chiral catalyst, resulting in high to quantitative yields and excellent enantioselectivities (up to 99% ee) of various hydrazino aldehydes in the presence of a benzoic acid additive.