[I:1]N1C(=O)CCC1=O.[CH:9]1([C:13]2[CH:22]=[CH:21][C:16]([C:17]([O:19][CH3:20])=[O:18])=[C:15]([CH3:23])[CH:14]=2)[CH2:12][CH2:11][CH2:10]1.CO>S(=O)(=O)(O)O>[CH:9]1([C:13]2[C:22]([I:1])=[CH:21][C:16]([C:17]([O:19][CH3:20])=[O:18])=[C:15]([CH3:23])[CH:14]=2)[CH2:10][CH2:11][CH2:12]1N-Iodosuccinimide (3.52 g, 15.6 mmol) was added portionwise to a solution of methyl 4-cyclobutyl-2-methylbenzoate (compound 152.2, 3.2 g, 15.6 mmol) in concentrated sulfuric acid (25 ml) at 0° C. The mixture was stiffed at 0° C. for 30 min and at RT for 2 hours. The mixture turned very thick. The mixture was cooled to 0° C. again and MeOH (30 ml) was added. The mixture was heated at 60° C. for 2 hours. The methanol was removed under reduced pressure and the residue was poured into ice water (100 ml). The mixture was extracted with EtOAc (2×). The combined organic layers were washed with brine, then aq. 1N NaHCO3 (note-significant gas evolution), dried (Na2SO4) and concentrated. The residue was purified using column (silica gel) chromatography (hexanes:EtOAc 30:1 to 20:1). Yield: 4.17 g, light yellow oil, 81%. 1H NMR (400 MHz, Chloroform-d) δ 8.33 (s, 1H), 7.14 (s, 1H), 3.87 (s, 3H), 3.67-3.54 (m, 1H), 2.57 (s, 3H), 2.51-2.40 (m, 2H), 2.14-1.97 (m, 3H), 1.82-1.79 (m, 1H).
Wird geladen…
