Asymmetric total syntheses of (+)-goniopypyrone (1) and (+)-deoxygoniopypyrone (2) from methyl cinnamate (7) via (DHQ)2-PHAL.-OsOi catalyzed asymmetric dihydroxylation and highly stereoselective 2-furylcopper addition in eight steps and eleven steps with overall yield of 20% and 13%, respectively, are described.The styryl lactones, (+)-goniopypyrone (1)l and 9-deoxygoniopypyrone ( 2),2 were recently isolated from the stem bark of Goniothalamus giganteus and shown to have significant cytotoxic a c t i~i t y .~,~ Due to the excellent bioactivity and interesting bicyclic skeleton, several groups have paid attention to the syntheses of the two styryl lac tone^.^-^ The synthetic methods, however, were almost all from carbohydrates4 or 2,3-O-isopropylidene-D-glyceraldeh de5t6 as the chiral materials. Herein we report methyl cinnamate ( 7 ) and highly stereoselective addition of 2-furylcopper to 11.Retrosynthetic analysis of 1 and 2 shows that the two precursors 2-pyranone (4) and ( 5 ) , which could be prepared from the common key intermediate furylmethanol (3), could be transformed into 1 and 2, respectively, by intramolecular Michael addition reactions (Scheme 1). Furthermore, from 3, another styryl lactone, 8-epigoniofufurone (6) was also synthesized in our previous work on styryl lactones.8Synthesis of the common key intermediate 3 is depicted in Scheme 2. Asymmetric dihydro~ylation~ of inexpensive methyl cinnamate ( 7 ) using 1,4-bis(9-0-dihydroquininy1)phthalazine [ (DHQ)z-PHAL] as chiral ligand produced the expected diol (8)g910 in yield of 89%. Protection of 8 with 2,a-dimethoxy propane in the presence of ptoluene sulphonic acid furnished the desired 9, which was reduced with lithium aluminium hydride to give alcohol (10) in yield of 94%. Swern oxidation of 10 afforded an unstable aldehyde (11). Because the reaction of 11 with 2-furyllithium produced a mixture of syw and antiadduct (syn:anti = 2:1), we gave attention to preparation of 2-furylcopper reagent" obtained from fury1 Grignard reagent12 and cuprous bromide or cuprous iodide. Swern oxidation of 10 followed by immediate addition of 2-furylcopper to the liberated aldehyde 11 gave almost exclusively the syn adduct 3 (the ratio of syn to anti adduct was determined to be 98.7:1.3 by glc analysis) in yield of 54%. The data of 'H NMR for the furfuryl protons of 3 and tert-butyldimethylsilylether of 3 were shown in Fig. l.13 the asymmetric total syntheses of 1 P and 2 involving asymmetric dihydroxylation of
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