[NH:1]1[CH:6]=[CH:5][CH:4]=[CH:3][C:2]1=[O:7].[O:8]1[C:10]2[CH2:11][CH2:12][CH2:13][C:9]1=2>[Pd].O1CCCC1.C([O-])(=O)C.[Pd+2].C([O-])(=O)C>[OH:8][CH:9]1[CH2:13][CH:12]([N:1]2[CH:6]=[CH:5][CH:4]=[CH:3][C:2]2=[O:7])[CH:11]=[CH:10]121 g (0.22 mol) of 2-pyridone are added at 0° C. to a solution of the palladium(0) catalyst prepared as above (2 mol % of palladium(II) acetate) in 200 ml of dry tetrahydrofuran, and 20.1 g (0.245 mol) of epoxycyclopentene, dissolved in 80 ml of tetrahydrofuran, are then added dropwise over a period of 2 hours, while stirring. The solution which forms is stirred at room temperature for 2 days and then concentrated, the residue is dissolved in methylene chloride, the solution is extracted by shaking with 1 A sodium carbonate solution and the organic phase is concentrated. The residue is chromatographed over silica gel using ethyl acetate/methanol 9/1. 7.2 g (18.49% of theory) of 1-[(1RS,4SR)-4-hydroxycyclopent-2-en-1-yl]pyridin-2(1H)-one are obtained as a viscous oil. 1H NMR (60 MHz, d6 -DMSO), δ[ppm]: 7.65-7.25 (m, 2H), 6.55-6.08 (m, 3H), 5.95-5.63 (m, 2H), 5.26 (d, 1H), 4.73 (m, 1H), 2.85 (m, 1H), 1.32 (m, 1H).
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