Reaction Steps
To a solution of the previous amino (0.35 g, 0.85 mmol) [Step 7] in anhydrous tetrahydrofuran (5 ml) was added 3-methylphenyl isocyanate (110 μl, 0.85 mmol) dropwise, under nitrogen. The resultant suspension was left to stand at room temperature for 1 h, after which time ether (20 ml) was added The solid was filtered off, washed with more ether and recrystallized from methanol to afford the title urea (290 mg, 62%) as a white solid. The mother liquors were evaporated and the residue chromatographed on silica gel, using 3:1 petrol-ethyl acetate followed by 1:1 petrol-ethyl acetate as the eluant. The product (103 mg, 22%) was isolated as a white solid; mp 202°-204° C. (MeOH); δH (360 MHz, CDCl3) 0.71 (3H, d, J=6.6 Hz), 0.78 (3H, d, J=6.6 Hz), 1.25-1.31 (1H, m), 1.43 (9H, s), 1.58-1.64 (2H, m), 1.73-1.77 (1H, m), 1.98-2.04 (1H, m), 2.31 (3H, m), 2.68-2.80 (2H, m), 2.91-2.98 (1H, m), 3.43 (1H, dd, J=13.8 and 5.1 Hz), 4.04-4.24 (2H, m), 4.29 (1H, dd, J=13.8 and 9.2 Hz), 5.33 (1H, d, J=6.5 Hz), 6.63 (1H, d, J=7.8 Hz), 6.70 (1H, s), 6.87 (1H, d, J=7.3 Hz), 7.08 (1H, d, J=8.1 Hz), 7.17 (1H, t, J=7.7 Hz), 7.20 (1H, s), 7.28 (1H, d, J=7.9 Hz), 7.36 (1H, d, J=8.0 Hz), 7.51 (1H, t, J=7.1 Hz), 7.56 (1H, d, J=7.9 Hz); m/z (CI, NH3) 547 (M+).
