1. Whaley, H. A.; Patterson, E. L.; Dann, M.; Shay, A. J.; Porter, J. N. Antimicrob. Agents Chemother. 1964, 8, 83–86.
2. Chopra, I. J.; Hodgson, B. M.; Poste, G. Antimicrob. Agents Chemother. 1997, 41, 497–503.
3. [α]D=−128° (c 0.23, H2O); HR-ESI-MS m/z 552.2910 (MH+, 10%, C27H42N3O9 requires: 552.2915), 276.6494 (MH22+, 100%); UV λmax (MeOH, HP1100 diode array detector) 272, 362 nm; IR νmax (KBr) cm−1 3403, 2942, 1655, 1600, 1465, 1451, 1381, 1347, 1234.
4. The absolute stereochemistry of lemonomycin has not been determined experimentally, but the configuration of the aglycon was depicted according to the absolute stereochemistry of the isoquinoline antibiotics, saframycins (Ref. 6).
5. A solution of lemonomycin (1, 25 mg) in isopropanol (1 ml), DMSO (0.5 ml), and trifluoroacetic acid (TFA, 15 ul) was stirred at rt for 16 h. The reaction mixture was then chromatographed by HPLC on a C18 column (5 μm, 30×250 mm), using a gradient solvent of 8–30% MeCN in water (0.05% formic acid) over 17 min (20 ml/min). The UV peak at 15 min was collected (25 ml), which contained compound 2. ESI-MS m/z 618.2 (MH+), UV λmax (0.01% TFA in MeCN/H2O, diode array detector) 272, 362 nm. To this solution, NaCN (30 mg) was added, and the resulting mixture was stirred for 15 h. The solution was then evaporated in vacuo, and the residue was separated by HPLC (C18 column, 15–30% MeCN in water (0.05% formic acid)) to afford 3 (10.2 mg, 40% overall yield). ESI-MS m/z 645.4 (MH+); UV λmax (0.01% TFA in MeCN/H2O, diode array detector) 272, 362 nm; 1H NMR (CD3OD) δ 4.88 (br d, 4.5 Hz, H-1′), 4.52 (d, 3.8 Hz, H-16), 4.04 (d, 2.5 Hz, H-17), 3.99 (3H, OCH3), 3.91 (m, H-5′), 3.89 (m, H-1), 3.78 (2H, m, CH’s on isopropoxy’s), 3.72 (dd, 10.2, 3.6 Hz, H-18), 3.71 (m, H-13), 3.53 (dd, 10.2, 1.5 Hz, H-18), 3.29 (m, H-11), 2.73 (br d, 10.5 Hz, H-3), 2.67 [6H, s, N(CH3)2], 2.66 (m, H-4), 2.36 (m, H-15), 2.20 (d, 1.8 Hz, H-4′), 2.02 (dd, 17.0, 2 Hz, H-4), 1.92 (3H, s, CH3-6), 1.85 (m, H-2′), 1.78 (2H, m, H2-14), 1.67 (br d, 14.4 Hz, H-2′), 1.30 (3H, d, 6.9 Hz, H3-6′), 1.17 (3H, s, CH3-3′), 1.11-1.18 (12H, m, CH3’s on isopropoxy’s).