Reaction Steps
Following General Procedure: Method B using (6R,6aS,14aR)-methyl 1,6,8,14a-tetrahydroxy-11-((2S,3R,4R,5R,6S)-4-hydroxy-3,5-dimethoxy-6-methyltetrahydro-2H-pyran-2-ylamino)-6a-methoxy-3-methyl-7,9,12,14-tetraoxo-5,6,6a,7,9,12,14,14a-octahydrobenzo[a]tetracene-2-carboxylate (35 mg, 0.050 mmol), potassium carbonate (21 mg, 0.15 mmol) and 3-picolyl chloride hydrochloride (25 mg, 0.15 mmol), the product was purified by preparative TLC (silica gel, 95:5 dichloromethane/methanol) and converted to hydrochloride to afford (6R,6aS,14aR)-methyl 6,8,14a-trihydroxy-11-((2S,3R,4R,5R,6S)-4-hydroxy-3,5-dimethoxy-6-methyltetrahydro-2H-pyran-2-ylamino)-6a-methoxy-3-methyl-7,9,12,14-tetraoxo-1-(pyridin-3-ylmethoxy)-5,6,6a,7,9,12,14,14a-octahydrobenzo[a]tetracene-2-carboxylate hydrochloride (13 mg, 31%) as an orange-red solid: 1H NMR (500 MHz, CDCl3) δ 14.21 (s, 1H), 8.79 (br s, 2H), 8.26 (d, J=4.1 Hz, 1H), 7.87 (br s, 1H), 7.41 (s, 1H), 6.92 (s, 1H), 6.89 (br s, 1H), 5.85 (s, 1H), 5.12 (d, J=11.2 Hz, 1H), 5.05 (d, J=11.3 Hz, 1H), 4.98 (br s, 1H), 4.66 (br s, 1H), 4.39 (br s, 1H), 3.85 (s, 3H), 3.81-3.74 (m, 1H), 3.72 (s, 3H), 3.65 (dd, J=19.3, 7.3 Hz, 1H), 3.60 (s, 3H), 3.43 (s, 1H), 3.40 (s, 3H), 3.36-3.31 (m, 1H), 3.14 (t, J=9.0 Hz, 1H), 2.51 (br s, 1H), 2.24 (s, 3H), 1.36 (d, J=6.1 Hz, 3H); MS (ESI+) m/z 789 (M+H); HPLC >99% (AUC), tR 12.34 min.
