Critical role of Bronsted acid in Lewis-acid-catalyzed synthesis of Amadori and Heyns compounds of β-amino acids

Amadori and Heyns rearrangement reactions are a century old reactions of the carbohydrates. The great body of literature on these reactions are concentrated on ɑ-amino acids. Reports on the synthesis and chemistry of Amadori and Heyns compounds derived from β-amino acids are scarce. We demonstrate herein, via Lewis-acid catalysis, synthesis of Amadori and Heyns compounds derived from β-amino acids consisting of β-alanine and β-phenylalanine with, D-xylose, D-galactose, D-fructose, D-mannose, D-maltose, D-lactose. The accomplished Lewis-acid catalyzed method is practical and devoid of separation techniques for achieving purity. We also report insight on the mechanism of Lewis-acid catalyzed Amadori and Heyns rearrangement reactions, and reveal the key role of Bronsted acid in Lewis-acid catalyzed Amadori and Heyns synthesis of β-amino acids.