Methylamine → 2,4-Dibromo-N-methylbutanamide

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Reaktionsschritte

Methyl 2,4-dibromobutyrate (50 gm, 0.192 mole) was mixed with 40 wt % methylamine in aqueous solution (20.0 ml, 7.22 gm, 0.232 mole) with stirring and cooling in an ice bath. The reaction mixture was stirred for 16 hours at 5° C., chloroform (100 ml) was then added and the organic layer washed with water. The organic extract was dried over magnesium sulfate, filtered and the solvent removed. The crude product was purified by column chromatography (silica gel, gradient elution hexane/chloroform to chloroform/ethylacetate) to yield an off-white solid, (25.4 gm, 51.7%): m.p. 42°-47° C. The compound was used in the next step without further purification. A small portion was further purified for elemental analysis; m.p. 48°-49° C. IR(KBr) 3450, 1660, 1570, 1415, 1240 and 1210 cm-1 ; H-NMR (CDCl3) δ 2.48 (m, 1H, --CH2 -CHBr--), 2.79(m, 1H, --CH2 -CHBy--), (d, 3H, --NH2 -CH3 --), 3.55 (t, 2H, Br--CH2 --CH2), 4.54 (dd, 1H, --CHBr--); 6.39 (s, broad, 1H, --NH--CH3), C--NMR, decoupled (CDCl3) 26.83, 30.27, 37.60, 48.26, 168.65 ppm. Anal. calcd. for C5H9NBr2O (258.949): C, 23.19; H, 3.50; N, 5.41. Found: C, 23.53; H, 3.44; N, 5.29%.

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