Rabbit muscle aldolase (RAMA) as a catalyst in a new approach for the synthesis of 3-deoxy-D-manno-2-octulosonic acid and analogues

A new approach leading to 3-deoxy-D-manno-2-octulosonic acid (KDO) and 4-deoxy-KDO is described. The key step is the formation of the C5C6 bond catalysed by fructose-1,6-bisphosphate aldolase, which controls the stereochemistry of these two centres. The important step of the aldehyde substrates (1a, 1b, 1c) synthesis is the Barbier reaction of ethyl-bromomethylacrylate or bromomethylacrylonitrile with the monoacetal of glyoxal in the presence of indium.