合成路线1

The previously reported alcohol (I) was used as the starting material for the synthesis of the title compound. Alcohol (I) was oxidized to aldehyde (II) using N-methylmorpholine-N-oxide in the presence of a catalytic amount of tetrapropylammonium perruthenate. The phenolic hydroxyl group of (II) was subsequently protected as the silyl ether (III) by treatment with triisopropylsilyl chloride. The symmetrical N,N-bis-acylated aminal (V) was synthesized by condensation of aldehyde (III) with amide (IV) in the presence of trimethylsilyl triflate. Elimination of one amide moiety of (V) with NaH in refluxing toluene produced a mixture of (E)- and (Z)-enamides, from which the desired (E)-isomer (VI) could be separated by flash chromatography either at this point or after the next step. Finally, desilylation with tetrabutylammonium fluoride in THF furnished the deprotected compound.