C4, C5, and C6 3-Deoxyglycosones: Structures and Reactivity

Summary Because of the importance of deoxyglycosones as reactive intermediates in the Maillard reaction, C 4 , C 5 and C 6 3-deoxyglycosones were prepared, their structures were elucidated, and their reactivity studied. Whereas 3-deoxyglucosone consists exclusively of bicyclic (hemi)acetal/(hemi)ketal structures, 3-deoxypentosone consists of monocyclic isomers with 63% hydrates ( gem -diols) present; 3-deoxytetrosone was found to occur as monocyclic and non-cyclic hydrates, with a free carbonyl present in 27% of the isomers. The reactivity (instability and browning) is in the order 3-deoxytetrosone > 3-deoxypentosone > 3-deoxyglucosone.