合成路线1

Reductive amination of 4,4-diethoxycyclohexanone (I) with benzylamine in the presence of sodium triacetoxyborohydride provided amino ketal (II). Subsequent benzyl group hydrogenolysis in (II) yielded the primary amine (III), which was acylated by 4-chlorobenzenesulfonyl chloride (IV) affording sulfonamide (V). Claisen condensation of ketone (V) with ethyl formate furnished the hydroxymethylene ketone (VI). This was subjected to a Wittig reaction with (methoxycarbonylmethylene)triphenylphosphorane to produce ester (VII). Intramolecular cyclization of (VII) under acidic conditions gave rise to the benzopyranone (VIII). Diels-Alder cycloaddition between methyl butynoate (IX) and benzopyranone (VIII) led to a mixture of two regioisomeric tetrahydronaphthalenes (X) and (XI). Reduction of this mixture of esters by means of LiAlH4 yielded the desired alcohol (XII) along with its regioisomer, which were further oxidized to the corresponding aldehydes employing 4-benzylpyridinium dichromate. Separation of the resultant mixture by column chromatography furnished the desired aldehyde (XIII).