合成路线1

Methyl (R)-7-(3-hydroxy-5-oxo-1-cyclopent-1-yl)heptanoate (I) was protected as the silyl ether (II) using tert-butyldimethylsilyl triflate and 2,6-lutidine. Conjugate addition to (II) of the organocuprate reagent derived from butenylmagnesium bromide (III) and CuBr produced adduct (IV). Reduction of the keto group of (IV) with NaBH4, followed by silylation of the resulting alcohol (V), furnished the bis-silyl ether (VI). Subsequent olefin oxidative cleavage by means of potassium osmate and sodium periodate gave rise to aldehyde (VII). To this was added 2-lithiobenzothiophene (VIII) to yield carbinol (IX). Desilylation of (IX) to triol (X) was then achieved by using HF in pyridine. The methyl ester group of (X) was finally hydrolyzed with LiOH to give the title carboxylic acid.