Organocatalytic Chemo- and Regioselective Acylation of Monosaccharides

Significance

The presented organocatalyst allows for the regio- and chemoselective acylation of the equatorial hydroxy group at carbon C(4) of monosaccharides. This is especially remarkable since the substrates not only contain a primary ­hydroxyl group but also two other secondary alcohols. The catalyst of choice contains a DMAP-type subunit as the active center and two tryptophans as directing groups. It mediates the acylations with usually high yields and in often excellent regio­selectivities. Mechanistic studies and transition-state models to explain the observed selectivities have been included in the paper.