[OH:1][C:2]1[C:17]([CH:18]=[N:19]O)=[C:6]2[CH:7]=[C:8]([C:10]3[CH:15]=[CH:14][C:13]([OH:16])=[CH:12][CH:11]=3)[O:9][C:5]2=[C:4]([O:21][CH3:22])[CH:3]=1.[H-].[Na+].[OH-].[Na+].Cl>CC(OC(C)=O)=O.CO>[OH:1][C:2]1[C:17]([C:18]#[N:19])=[C:6]2[CH:7]=[C:8]([C:10]3[CH:11]=[CH:12][C:13]([OH:16])=[CH:14][CH:15]=3)[O:9][C:5]2=[C:4]([O:21][CH3:22])[CH:3]=1The crude 7 oxime 72 was heated in neat Ac2O at 100° C. for 30 minutes. The Ac2O was removed and the crude product was dissolved in EtOAc, washed with brine and dried over MgSO4. The solution was concentrated down and the crude triacetate was dissolved in DMF (10 mL) and treated with NaH (0.1 g, 60% dispersion in mineral oil, 2.5 mmol) and the reaction mixture was heated to 100° C. for 15 min. After cooling to rt, the solution was treated with a 20% NaOH aq solution and enough MeOH to get everything in one phase. This solution was then heated briefly (long enough to hydrolyze the acetates as determined by TLC analysis) and allowed to cool back to rt. The solution was acidifed with 2N HCl aq and the solution was extracted with EtOAc. The EtOAc extract was washed with NaHCO3 and brine and dried over MgSO4. The solution was filtered, concentrated and chromatographed on silica gel (2:8 to 4:6 EtOAc/hexanes) to yield 80 mg of the pdt nitrile 73 as a white solid: Mp=286-288° C.; 1H NMR (DMSO-d6) δ 10.9 (br s, 1 H), 9.98 (br s, 1 H), 7.77 (d, 2 H, J=8.7 Hz), 7.20 (s, 1 H), 6.87 (d, 2 H, J=8.7 Hz), 6.48 (s, 1 H), 3.97 (s, 3 H).
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