51-2 (0.15 g, 0.53 mmol) was first treated with neat trifluoroacetic acid for 30 minutes at room temperature. The trifluoroacetic acid was then evaporated off and the residue was dissolved in n-butanol (3 mL). To this was added 35-1 (0.13 g, 0.53 mmol) and triethylamine (0.27 g, 2.65 mmol). This was heated at 150° C. for 18 hours and then the solid was filtered off, washed with n-butanol and then ethyl ether to afford 51-3. Hi-Res MS: calc: 385.1554 found: 385.1551. 1H-NMR (DMSO-d6): 12.02 (s, 1H); 8.41 (s, 1H); 8.25 (s, 1H); 7.44 (s, 1H); 6.20 (s, 1H); 3.51 (br s, 4H); 3.13 (m, 1H); 3.05 (m, 2H); 2.93 (m, 2H); 2.63 (m, 2H); 1.62–1.83 (complex, 4H).
