[N:1]1[CH:6]=[CH:5][CH:4]=[C:3]([C:7]2[S:11][C:10]([CH:12]=O)=[CH:9][CH:8]=2)[CH:2]=1.CN.Cl.[C:17]([BH3-])#[N:18].[Na+]>CO.O1CCOCC1>[CH3:17][NH:18][CH2:12][C:10]1[S:11][C:7]([C:3]2[CH:2]=[N:1][CH:6]=[CH:5][CH:4]=2)=[CH:8][CH:9]=1
To a solution 13 (90 mg, 0.48 mmol) was added a solution of methylamine (2.0 M, 1.43 mL, 2.85 mmol) in anhydrous CH3OH, a solution of HCl (4.0 M, 0.24 mL, 0.95 mmol) in anhydrous 1,4-dioxane and sodium cyanoborohydride (30 mg, 0.48 mmol). The flask was purged with argon and stirred under an atmosphere of argon at room temperature for 24 h. The solution was adjusted to pH 2 with conc. HCl and the solvent was removed in vacuo. The residue was dissolved in water and washed with Et2O (3×10 mL). The aqueous fraction was adjusted to pH 10 with NaOH(aq) (10 N), extracted with Et2O (3×20 mL), dried (Na2SO4), filtered and the solvent was removed in vacuo. The crude material was chromatographed on silica gel (CH3OH/CHCl3, 10/90, Rf=0.13) to afford the title compound 40 (39 mg, 40% yield) as a yellow oil: 1H NMR (CDCl3) δ 8.84 (m, 1H), 8.49 (m, 1H), 7.82 (m, 1H), 7.28 (m, 1H), 7.21 (d, J=3.6 Hz, 1H), 6.93 (d, J=3.5 Hz, 1H), 3.96 (s, 2H)2.31 (s, 3H); LRMS (ESI) m/z calcd for C11H13N2S [M+H]+ 205. found 205; m/z calcd for C10H8NS [M−NH(CH3)]+ 174. found 174; HRMS (ESI) m/z calcd for C11H13N2S [M+H]+ 205.0799. found 205.0781; HPLC>95%=4.34 min, 80 (A):20 (B): 0.05 (C); tR=3.60 min, 60 (A):40 (B): 0.07 (C)).
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