Synthesis of L ‐Altrose and Some Derivatives

A convenient approach to the chemical synthesis of L ‐altrose ( 1 ) and its 6‐deoxy derivative 2 has been developed by starting from D ‐galactose ( 9 ) and D ‐fucose ( 10 ), respectively. The 5‐epimerization by a Mitsunobu inversion of the open‐chain D ‐hexoses was the key step for these routes. Furthermore, the conversion of 2 into peracetylated TDP‐6‐deoxy‐α‐ L ‐altrose ( 3a ) was achieved by the cyclo Sal approach. However, the final deacetylation led to an unexpected side‐reaction resulting in the previously unknown 6‐deoxy‐α‐ L ‐altropyranose 1,3‐cyclophosphate ( 4 ).