Synthesis of intermediate (VIII). The hydrochloration of 5-oxotricyclo[2.2.1.0~2,6~]heptane-3-carboxylic acid (II) gives 2-chloro-5-oxobicyclo[2.2.1]heptane-7-carboxylic acid (III), which is treated with peracetic acid yielding lactone (IV). This compound is treated with SOCl2 to obtain acyl chloride (V), which is converted into aldehyde (VI) by means H2 over Pd. The Horner-Emmons-Wiittig reaction of aldehyde (VI) and phosphonate (VII) by means NaH affords intermediate (VIII).
Synthesis of intermediate (XII). Ring cleavage and rearrangement of compound (VIII) affords enone (IXa) with an unprotected hydroxyl group. By stereoselective reduction of (IXa), diol (XIa) is obtained, which is finally protected by DHP to obtain intermediate (XII).
Intermediate (XII) is converted in four steps through the 獵orey synthesis?to Dimoxaprost.