[摘要]：The BCD-ring substructure of granaticin A was synthesised following a new approach for the construction of the naphthoquinone moiety. The 2-oxabicyclo[2.2.2]oct-5-ene substructure was accessible stereoselectively using a Sharpless asymmetric dihydroxylation and a diastereoselective ketone reduction in combination with Yoshii's route. The naphthoquinone B-ring was prepared by addition of an aryllithium intermediate to an anhydride followed by a FriedelCrafts cyclisation mediated by AlCl3 and Mg(OTf)2. The success of the FriedelCrafts cyclisation relied on the conversion of the ketone-carboxylic acid into a lactone acetal. |
