Dimethylamine → (Dihydro-3,3-diphenyl-3H-furan-2-ylidene)dimethylammonium bromide

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Reaction Steps

To a suspension of 4-bromo-2,2-diphenylbutyric acid from Step A (227 g, 0.70 mol) in CHCl3 (1500 ml) was added dropwise SOCl2 (160 ml). This mixture was refluxed for 4 hrs and allowed to cool, and the solvent was removed in vacuo. The crude 4-bromo-2,2-diphenylbutyroyl chloride (227 g, 93%) was used without further purification. To a solution of dimethylamine (54 g, 0.12 mol) and Na2CO3 (25.4 g, 0.24 mol) in H2O (100 ml) was added dropwise a solution of 4-bromo-2,2-diphenylbutyroyl chloride (33.8 g, 0.1 mol) in toluene (100 ml), while the temperature was maintained between 0 and 5° C. The mixture was stirred for an additional 2 hrs and extracted with CHCl3. The organic layer was dried (MgSO4) and the solvent was removed in vacuo. The residue was crystallized from i-BuCOMc to give pure dimethyl-(tetrahydro-3,3-diphenyl-2-furylidene)ammonium bromide. (17.3 g, 50%): mp 181-182°: UV max (95% EtOH) 255 nm (540) and 261 (425); IR (KBr) 1675-1680 cm-1 (C=N); nmr (CDCl3) δ3.03 (s, 3), 3.50 (t, 2), 3.8 (s, 3), 4.89 (t, 2), and 7.51 ppm (s, 10).

Provenance & Evidence