Dichloromethane → trans-N-[2-(Dimethylamino)cyclohexyl]-3-hydroxy-4-nitro-benzamide

Participants

Reaction Steps

A solution of boron tribromide (7.52 g.; 0.03 mole) in 20 ml. of CH2Cl2 was added to a solution of trans-N-[2-(dimethylamino)cyclohexyl]-3-methoxy-4-nitrobenzamide (1.93 g.; 0.006 mole) in 50 ml. of CH2Cl3 keeping the temperature at -50° to -70°. It was allowed to warm to room temperature and stirred overnight. The mixture was concentrated in vacuo at 30° to a small volume, ice-water was added followed by solid NaHCO3 to pH 8, then solid NaCl and extracted with ethyl acetate (5 × 100 ml). The extract was dried (MgSO4) and evaporated to give 0.657 g. of solid. The aqueous was extracted again with CHCl3 (4 × 100 ml.) to give 0.561 g. of solid. The last extraction was repeated to give 0.3 g. of solid. The three crops were crystallized from benzene to give 0.548 g. of orange prisms, m.p. 139°-140°. The analytical sample melted at 138°-140° (efferv.). NMR analysis showed this product to contain ca. 30% of benzene. This impure titled product was heated at 120°-125° for 17 hours in a sublimation tube (the m.p. changed to 198°-199.5°) and was then sublimed at 170°-175° for 18 hours. The sublimate, orange prisms, melted at 202°-203.5°. uv λmax 238 nm nm (ε 11,600); 278 (7,900); 358 (2,350); 422 (2,850). ir NH/=CH/N+H/OH 3220, 3180, 3020, ~ 2900 broad, C=O 1655; C=C 1600; amide II/NO2 /C=C 1580, 1485, 1335; C-N/-C-O 1260, 1240, 1220, 1155, 995. NMR in CDCl3 + d6DMSO (100 MHz) showed absence of benzene. Mass spectrum M+ 307.

Provenance & Evidence