Synthesis of 4-deoxyquinic, 4-deoxyshikimic and 4-deoxy-3-dehydroshikimic acids

The synthesis of 4-deoxyquinic acid (1b) from (–)-quinic acid (1a) and 4-deoxyshikimic acid (4b) from shikimic acid (4a) respectively are described. 4-Deoxyshikimic acid (4b) was converted enzymatically into 4-deoxy-3-dehydroshikimic acid (3b) using shikimate dehydrogenase. The C(4) hydroxy group is shown not to contribute significantly to substrate specificity for shikimate dehydrogenase. Attempts to synthesise 4-deoxy-3-dehydroquinic acid (2b) are described.