Reaction Steps
The compound of Example 7 (500 mg) was suspended in water (4 ml) and sodium hydroxide (44 mg) added. This was heated to an external temperature of 96° C. and dimethyl sulphate (65 mg) added. The reaction mixture was allowed to stir under nitrogen at 96° C. for 1 h after which time stirring was continued for 24 h at 5° C. After this time, the product was extracted into dichloromethane and washed with water and brine. The organic layer was dried (MgSO4) and evaporated. The residue was purified on silica using medium pressure chromatography (Lobar), and eluted with 25% ethyl acetate in petrol. The first compound to be eluted was isolated, and this afforded the product (50 mg) as a crystalline solid, which was recrystallised from ether/hexane to afford white crystals: mp 139°-141° C. 1H NMR (360 MHz, DMSO) d 1.44-1.51 (2H, m, CH2), 1.79-1.82 (1H, m, CHH), 2.12-2.15 (1H, m, CHH), 2.19-2.25 (1H, m, CHHN), 2.97-3.00 (1H, m, CHHN), 3.37 (1H, d, J=14 Hz, N--CHH-tetrazole), 3.52 (1H, s, NCHCHO), 3.58 (1H, s, NCHCHO), 3.81 (1H, d, J=14 Hz, N--CHH-tetrazole), 4.03 (1H, d, J=13 Hz, OCHH), 4.31 (3H, s, CH3), 4.60 (1H, d, J=13 Hz, OCHH), 7.23-7.33 (3H, m, ArH), 7.49-7.51 (2H, m, ArH), 7.68 (2H, s, ArH), 7.93 (1H, s, ArH); MS (CI+) m/z 500 ((M+1)+, 100%). Found: C, 55.56; H, 4.76; N, 14.20. Calculated for C23H23N5OF6 : C, 55.31; H, 4.64; N, 14.02%.
