[CH3:1][N:2]1[CH:6]=[CH:5][N:4]=[C:3]1/[CH:7]=[N:8]/[S:9]([C:11]([CH3:14])([CH3:13])[CH3:12])=[O:10].[CH2:15]1COCC1.C[Mg]Br.CCOCC>[NH4+].[Cl-]>[CH3:1][N:2]1[CH:6]=[CH:5][N:4]=[C:3]1[CH:7]([NH:8][S:9]([C:11]([CH3:14])([CH3:13])[CH3:12])=[O:10])[CH3:15]
In a 250 mL round-bottomed flask, 2-methyl-propane-2-sulfinic acid 1-(1-methyl-1H-imidazol-2-yl)-meth-(E)-ylideneamide (670 mg, 3.14 mmol) was combined with THF to give a colorless solution. Methylmagnesium bromide in ether (3.0 M, 5.24 ml, 15.7 mmol) was added at 0° C. The reaction was stirred at 0° C. for 2 h. The reaction mixture was diluted with sat aq. NH4Cl. The aqueous layer was back-extracted with dichloromethane (2×100 mL). The aqueous layer was back-extracted with EtOAc (1×125 mL). The crude reaction mixture was concentrated in vacuo to provide 700 mg (92%) of 2-methyl-propane-2-sulfinic acid [1-(1-methyl-1H-imidazol-2-yl)-ethyl]-amide as a single diastereomer. 1H NMR (300 MHz, DMSO-d6): δ 6.98 (bs, 1H), 6.82 (bs, 1H), 4.61 (q, 1H, J=6 Hz), 4.10 (bs, 1H), 1.61 (d, 1H, J=6 Hz), 1.29 (s, 9H).
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