Stereoselective Synthesis of 1,2-13C2-L-Fucose, 1,2-13C2-Fucono-(gamma)-lactone and 1,2-13C2-Fucono-(gamma)lactol from Non-Sugar Starting Material

An efficient synthesis is reported for the preparation of L-fucose, and of L-fucofuranose, from 1. The route is designed to facilitate 13C labelling at C1 and/or C2, and the synthesis of 1,2-13C2-fucose as its tetraacetate is described. The C2 and C3 stereocentres are introduced using asymmetric dihydroxylation, and the lactone ring size resulting from cyclisation of 4 was controlled to provide the L-fucofuranone 5, whose structure was unambiguously established by X-ray crystal analysis of the derived trisilyl ether 6. Generation of the fucose lactol 7 by reduction of 6 followed by deprotection then provided L-fucose, isolated as its peracetate 8.