Synthesis of 7-O-galloyl-D-sedoheptulose.

A facile synthetic approach to 7-O-galloyl-D-sedoheptulose (1), a natural product with notable immunosuppressant activity, was developed. The starting material, 2,7-anhydro-d-sedoheptulose (2), was converted in three steps into 1,3,4,5-tetra-O-benzyl-d-sedoheptulose (5), a key intermediate that allows specific functionalization at C-7 of the sedoheptulpyranose. After regioselective esterification of 5 with 3,4,5-tri-O-benzyl galloyl acid, followed by catalytic debenzylation (Pd-C), 1 was obtained in an overall yield of 60%. The spectroscopic data and TLC behavior of 1 were found to be identical to that of the natural product.