A New Short and Efficient Route to 3-Deoxy-<scp>d</scp>-<i>manno</i>-oct-2-ulosonic Acid (KDO) and 3-Deoxy-<scp>d</scp>-<i>arabino</i>-hept-2-ulosonic Acid (DAH)
An efficient synthesis of lactones 5 and 6, known intermediates towards KDO and DAH, respectively, has been achieved by a short and highly efficient route. Homologation of protected D-mannose and D-arabinose was performed by a Peterson reaction with 2-lithio-2-trimethylsilyldithiane or the corresponding bis(methylsulfanyl) derivative, followed by the cyclization of the resulting ketene dithioacetal