Stannous chloride dihydrate → 1-(3-Amino-4-Methylphenyl)Ethanone

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Tin(II)dichloride dihydrate (37 g, 168 mmol) was added to 4-methyl-3-nitroacetophenone (10 g, 56 mmol) dissolved in methanol (350 mL). The reaction mixture was heated at 60° C. for 18 h, concentrated, and dried under high vacuum to give to 1-(3-amino-4-methylphenyl)ethanone which contained tin salts. LC (Cond.-J1): 0.73 min; LC/MS: Anal. Calcd. for [M+H]+ C9H11NO: 150.08; found: 150. The material was used without purification. HATU (10.6 g, 28 mmol) was added in one portion to a stirred solution of 1-(3-amino-4-methylphenyl)ethanone (4.1 g, 28 mmol), N-Boc-L-proline (6 g, 28 mmol), and Hunig's base (25 mL) in DMF (225 mL) and the reaction mixture was stirred 18 h. The solvent was removed in vacuo and the residue was taken up in ethyl acetate/methanol (1:1) and applied to a flash SiO2 column. A step elution by gradient 20%; 50%; 75%; 100% B (total elution vol 1500 mL); A=hexanes; B=ethyl acetate; and a final elution with; 10% methanol/ethyl acetate was conducted to give J.38, 4.4 g (46%). 1H NMR (300 MHz, DMSO-d6) δ: 9.51/9.45 (s, 1H), 7.95-7.92 (m, 1H), 7.70 (d, J=8.0 Hz, 1H), 7.37 (d, J=7.7 Hz, 1H), 4.33-4.29 (m, 1H), 3.48-3.29 (m, 2H), 2.50 (s, 3H), 2.26 (s, 3H), 1.98-1.80 (m, 4H), 1.41/1.36 (m, 9H). LC (Cond.-J1): 1.70 min; LRMS: Anal. Calcd. for [M+H]+ C19H27N2O4: 347.20; found 347.41.

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