合成路线1

Friedel Crafts' condensation of phloroglucinol (I) with 3,3-dimethylacrylic acid (II) in the presence of boron trifluoride etherate gave the dihydroxy chromanone (III). Selective alkylation of the 7-hydroxyl group of (III) with iodomethane in the presence of K2CO3 furnished the methyl ether (IV). The carbonyl group of (IV) was subsequently reduced with NaBH4 in refluxing THF under basic conditions to produce chroman (V). The lactone ring of (VII) was then formed by a Pechmann reaction of (V) using ethyl acetoacetate (VI) and boron trifluoride to afford the tricyclic compound (VII). Dehydrogenation of (VII) employing DDQ in refluxing dioxan gave (VIII). The target 3'R,4'R-dihydroxylated derivative (IX) was obtained by Sharpless asymmetric dihydroxylation of (VIII) with hydroquinine 2,5-diphenyl-4,6-pyrimidinediyl diether ((DHQ)2-PYR) as the chiral catalyst. Diol (IX) was finally esterified with (-)-S-camphanoyl chloride (X) to afford the title diester.