合成路线1

The condensation of 2-bromo-3-hydroxy-4-methoxybenzaldehyde (I) with the cyclohexenecarboxylate (II) by means of a Pd catalyst and a chiral auxiliary gives the chiral aryl ether (III), which is treated with methyl orthoformate and Ts-OH in methanol to yield the dimethylacetal (IV). The reduction of the ester group of (IV) by means of DIBAL affords the methanol derivative (V), which is treated with acetone cyanohydrin, PPh3 and Ts-OH to provide the acetonitrile derivative (VI). The cyclization of (VI) by means of Pd(OAc)2 and Ag2CO3 in refluxing toluene leads to the tetrahydro dibenzofuran derivative (VII), which is diastereoselectively oxidized by means of SeO2 in hot dioxane to give the chiral secondary alcohol (VIII). The reaction of (VIII) with methylamine in methanol yields the methylimine (IX), which is submitted to reductocyclization by means of DIBAL to afford the tetracyclic intermediate (X). This compound, without isolation, is reduced with NaBH3CN to provide the target galanthamine.