Carbohydrate-based synthesis of crocacin: stereoselective Heck reaction of carbohydrate 5,6-ene- and 5,6-yne-derivatives with aromatic halides

The Heck reaction between a carbohydrate 5,6-ene derivative 9 and an aromatic halide exclusively gave rise to the β-carbohydrate-substituted trans-styrene derivative 8; while the corresponding Wittig reaction produced a cis/trans mixture in which the cis-isomer predominated. The application of the Heck reaction is described to synthesize the intermediate 5, commonly used in the synthesis of members of the crocacin family.