Cyclobutylamine → 1-cyclobutyl-1H-imidazole-4-carboxylic acid ethyl ester
Reaction equation
C[N:2]([CH3:12])[CH:3]=[C:4]([N+:10]#[C-:11])[C:5]([O:7][CH2:8][CH3:9])=[O:6].[CH:13]1(N)[CH2:16]C[CH2:14]1>>[CH2:8]([O:7][C:5]([C:4]1[N:10]=[CH:11][N:2]([CH:12]2[CH2:16][CH2:13][CH2:14]2)[CH:3]=1)=[O:6])[CH3:9]Participants
3
Procedure
Ethyl 3-(dimethylamino)-2-isocyanoacrylate (WO 2007042545) (45 g, 0.27 mol) was added to cyclobutylamine (50 g, 0.70 mol) and heated to reflux for 2 hours. The solution was then cooled and concentrated. The residue was purified by column chromatography over silica gel (3:1 EtOAc:Heptane). The oily residue was triturated with TBME:heptane (1:1) and the resulting solid was collected and dried, giving 1-cyclobutyl-1H-imidazole-4-carboxylic acid ethyl ester (35 g, 67%, second crop not harvested). 1-Cyclobutyl-1H-imidazole-4-carboxylic acid ethyl ester (35 g, 0.21 mol) was dissolved in 6 N HCl (300 mL) and refluxed for 1 day. The solution was concentrated to dryness in vacuo. The solid was azeotroped with toluene, triturated with toluene and then dried under vacuum, giving the title compound 88% yield, 37.2 g, m/z 167 [M+H]+.