合成路线1

The esterification of the carboxylic acid (II) with 2-iodo-6-methoxyphenol (I) by means of EDC and DMAP in dichloromethane gives the corresponding ester (III), which is cyclized by means of a Pd catalyst and TlOAc in refluxing acetonitrile to yield the spiranic 1-benzopyranone (IV). The cleavage of the ethylene ketal group of (IV) with Ph3C-BF4 in dichloromethane affords the spiranic diketone (V), which is dehydrogenated with (Ph-SeO)2O in refluxing dichloromethane to provide the spiranic cyclohexadienone (VI). The reaction of dienone (VI) with methylamine resulted in a spontaneous Michael addition to give the N-methylamide (VII), which is cyclized with paraformaldehyde and TFA yielding the tetracyclic compound (VIII). The enantioselective reduction of the ketonic group of (VIII) with L-Selectride in THF affords the alcohol (IX), which is finally reduced with LiAlH4 providing the target galanthamine.