Chemoenzymic Approaches to the Preparation of 5-C-(Hydroxymethyl)hexoses

Synthesis of 5-C-(hydroxymethyl)hexoses, carbohydrates resistant to metabolism, is described. These compounds are obtained in the reaction of hexose 6-aldehydes with formaldehyde. 5-C-(Hydroxymethyl)-L-arabino-hexopyranoses can be efficiently obtained from D-galactosides by a two-step chemoenzymic synthesis using galactose oxidase for the preparation of required hexose 6-aldehydes. This method is an example of carbohydrate synthesis without use of protecting groups. Other 5-C-(hydroxymethyl)hexoses are prepared by a typical chemical methodology requiring specific protection of the hexose hydroxyl groups.