Gram scale de novo synthesis of 2,4-diacetamido-2,4,6-trideoxy-D-galactose

In contrast to the infection with Gram-negative bacteria, the precise mechanism of infection with their Gram-positive counterparts is still poorly understood. It has been established, that teichoic and lipoteichoic acids play an important role in host-pathogen interaction. The bacterium Streptococcus pneumoniae is one of the severe life-threatening Gram-positive pathogens and elucidation of the structure of its lipoteichoic acid revealed 2,4-diacetamido-2,4,6-trideoxy-d-galactose as a main component of the cell wall glycopolymer. Our approach toward this carbohydrate used an l-threonine derived aldehyde as starting material following the Garner protocol, which was subjected to a nitro aldol reaction with 2-nitroacetaldehyde diethylacetal to generate the galacto configurated carbon backbone. Subsequent reduction of the nitro group and peracetylation of the molecule resulted in a fully and orthogonally protected derivative, which was deprotected by a single step in pure deionized water at elevated temperatures.