A New Short and Efficient Route to 3-Deoxy-d-manno-oct-2-ulosonic Acid (KDO) and 3-Deoxy-d-arabino-hept-2-ulosonic Acid (DAH)

Abstract 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 under very smooth conditions. An oxidative treatment with iodine gave the lactones 5 and 6 in a three-step sequence with high yields. Interestingly, this approach can be considered as a general method for the synthesis of various 2-deoxy­sugar lactones.