Tert-butyl 2-(2,4-dichlorobenzylidene)-3-oxobutanoate → 6-Tert-butyl 3-ethyl 5-(2,4-dichlorophenyl)-7-methyl-5,8-dihydroimidazo[1,2-a]pyrimidine-3,6-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

Ethyl 2-amino-1H-imidazole-4-carboxylate (980 mg, 6.8 mmol) and tert-butyl 2-(2,4-dichlorobenzylidene)-3-oxobutanoate (2.03 g, 6.4 mmol) were dissolved in ethanol (15 mL) and the reaction was heated to 75° C. for 16 h. The reaction was concentrated under reduced pressure to obtain a 10:1 mixture (by HPLC) of 6-tert-butyl 2-ethyl 5-(2,4-dichlorophenyl)-7-methyl-5,8-dihydroimidazo[1,2-a]pyrimidine-2,6-dicarboxylate and 6-tert-butyl 3-ethyl 5-(2,4-dichlorophenyl)-7-methyl-5,8-dihydroimidazo[1,2-a]pyrimidine-3,6-dicarboxylate (3.07 g, 100% crude yield) as a yellow foam. A small amount of this mixture (350 mg) was purified by silica gel chromatography to obtain 6-tert-butyl 2-ethyl 5-(2,4-dichlorophenyl)-7-methyl-5,8-dihydroimidazo[1,2-a]pyrimidine-2,6-dicarboxylate (190 mg, 54%) and 6-tert-butyl 3-ethyl 5-(2,4-dichlorophenyl)-7-methyl-5,8-dihydroimidazo[1,2-a]pyrimidine-3,6-dicarboxylate (19 mg, 5.4%) as white solids.

Provenance & Evidence