合成路线1

The formylation of 6-bromo-1,3-benzodioxole-5-carbaldehyde dimethyl acetal (I) with BuLi and DMF gives the 6-formyl derivative (II), which is reduced with NaBH4 in ethanol to yield the corresponding carbinol (III). The cyclization of (III) with dimethyl acetylenedicarboxylate (V) in hot acetic acid (through the nonisolated intermediate (IV)) affords dimethyl 1,4-epoxy-6,7-(methylenedioxy)naphthalene-2,3-dicarboxylate (VI), which is hydrogenated with H2 over Pd/C in ethyl acetate to give the (1R*,2S*,3R*,4S*)-tetrahydro derivative (VII). The reduction of (VII) with LiAlH4 in refluxing ethyl ether affords the corresponding bis carbinol (VIII), which is treated with acetic anhydride to afford the diacetate (IX). The enzymatic monodeacetylation of (VIII) with PPL enzyme in DMSO/buffer gives (1R,2R,3S,4S)-2-(acetoxymethyl)-1,4-epoxy-3-(hydroxymethyl)-6,7-(methylenedioxy)-1,2,3,4-tetrahydronaphthalene (X), which is silylated with TBDMS-Cl and imidazole in DMF yielding the silyl ether (XI). The hydrolysis of the acetoxy group of (XI) with K2CO3 in methanol affords the carbinol (XII), which is oxidized with oxalyl chloride in dichloromethane affording the carbaldehyde (XIII). The exchange of the silyl protecting group of (XIII) (for stability problems) provided the triisopropylsilyl ether (XIV), which is treated with sodium methoxide in methanol to open the epoxide ring yielding the hydroxy aldehyde (XV). The protection of the hydroxy group of (XV) with 2-(trimethylsilyl)ethoxymethyl chloride and DIEA in dichloromethane provides the corresponding ether (XVI). The carbinol (III) can also be obtained directly from 6-bromo-1,3-benzodioxole-5-carbaldehyde dimethyl acetal (I) by reaction with formaldehyde and BuLi in THF.