Organotransition metal modified sugars: Part 23. Synthesis of vinylcarbene chromium complexes containing a C-monosaccharide ligand

Organometallic C-glycosides containing a chromium carbene functionality have been synthesized from pentacarbonyl[(methoxy)methylcarbene]chromium (1) in a TiCl4-assisted aldol condensation with formyl glycosides. The condensation is trans-selective to give a 54–82% yield of chromium vinylcarbene C-glycosides 5, 6 and 8 which are promising candidates for subsequent Diels–Alder, Michael addition, benzannulation and cyclopropanation reactions.