合成路线1

Racemic compound.- The reaction of 1,1-diacetylcyclopropane (I) with the disilylated propargyl alcohol (II) by means of tert-butyllithium gives the monocondensation compound (III), which is treated with ethynylmagnesium bromide (IV) and CeCl3 to yield the bis acetylenic diol (V). The acylation of (V) with acetic anhydridde affords the monoacetate (VI), which is isomerized by means of [CuH(PPh3]6 to provide the allene compound (VII). The selective deprotection of (VII) gives the terminal acetylene (VIII), which is cyclized with Mo(CO)6 in refluxing DMSO/toleuene to afford the tricyclic ketone (IX). The methyletion of (IX) with CH3Li gives the monosilylated tricyclic diol (X), which is deprotected with TBAF yielding the diol (XI). The oxidation of the secondary alcohol of (XI) with Dess Martin periodinane (DMP) provides the tricyclic ketone (XII), which is finally hydroxymethylated with formaldehyde and sulfuric acid to afford the target compound as a racemic mixture.