Reaction Steps
A solution of 1.2 g (3.7 mmol) of 3-methylsulfanyl-4-(t-butyidimethylsilyloxy)methyl-1,3-dihydro-indol-2-one in THF (25 mL) was stirred with saturated ammonium chloride solution (20 mL), and activated zinc dust (5 g) was added. The mixture was stirred for 60 h at rt. The organic phase was separated, dried over MgSO4 and concentrated to give 1,16 g of impure 4-(t-butyidimethylsilyloxy)methyl-1,3dihydro-indol-2-one as an off-white solid: 1H NMR (DMSO-d6): δ 0.11 (s, 6H), 0.86 (s, 9H), 3.42 (s, 2H), 4.67 (s, 2H), 6.74 (d, J=7.7 Hz, 1H), 6.95 (d, J=7.7 Hz, 1H), 7.18 (t J=7.7 Hz, 1H), 10.40 (s, 1H). A solution of 0.64 g (2.3 mmol) of 4-(t-butyldimethylsilyloxy)methyl-1,3-dihydro-indol-2-one in DMF dimethylacetal (5 mL) was heated to 100° C. for 1 h. The excesss DMF dimethylacetal was removed under high vacuum, and the resulting dark oil was chromatographed on silica gel, eluting with EtOAc, to give 0.34 g (44%) of 3-dimethylaminomethylene-4-(t-butyidimethyl-silyloxy)methyl-1,3-dihydro-indol-2one as a white solid: 1H NMR (DMSO-d6): δ −0.03 (s, 6H), 0.81 (s, 9H), 3.29 (s, 6H), 4.64 (s, 2H), 6.66 (d, J=7.3 Hz, 1H), 6.73 (d, J=7.3 Hz, 1H), 6.79 (t, J=7.3 Hz, 1H), 7.76 (s, 1H), 9.97 (s, 1H)); APCI−MS m/z 333 (M+1)+. A solution of 0.115 g (0.34 mmol) of 3-dimethylaminomethylene-4-(t-butyidimethylsilyloxy)methyl-1,3dihydro-indol-2-one in ethanol (10 mL) was treated with 0.076 g (0.34 mmol) N-methylsulfanilamide hydrochloride. The solution was refluxed for 0.5 h and cooled to rt. The resulting yellow precipitate was isolated by filtration, washed with ethanol and dried to yield 0.048 g (38%) of the title compound: 1H NMR (DMSO-d6): δ 2.37 (d, J=5.0 Hz, 3H), 4.67 (s, 2H), 5.3 (bs, 1H), 6.78 (d, J=7.5 Hz, 1H), 6.93 (d, J=7.5 Hz, 1H), 6.99 (t, J=7.5 Hz, 1H), 7.33 (q, J=5.0 Hz, 1H), 7.44 (d, J=8.6 Hz, 2H), 7.71 (d, J=8.6 Hz, 2H), 8.32 (d, J=12.2 Hz, 1H), 10.67 (s, 1H), 11.26 (d, J=12.2 Hz, 1H); APCI−MS m/z 358 (M−1)−. Anal. Calcd for C17H17N3O4S: C, 56.81, H, 4.77; N, 11.69, S, 8.92. Found C, 56.89, H, 4.81; N, 11.70; S, 8.84.
