Dimethylformamide → tert-Butyl 5-[(cis-3,5-dimethylpiperazino)carbonyl]imidazo[1,5-a]quinoline-3-carboxylate

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Reaction Steps

Potassium tert-butoxide (2.6 ml, 1.0M in THF) is added to a mixture of cis-3,5-dimethylpiperazino 2-chloroquinoline-4-carboxamide (X, 704 mg ), tert-butyl isocyanoacetate (IX. 390 mg ) and DMF (10 ml) at -78°. The mixture is stirred for 1 hr at -78° and is allowed to warm to 20°-25° over several hours. After stirring at 20°-25° for 16 hrs, water is added and the mixture extracted several times with ethyl acetate, the combined organic phases are dried over magnesium sulfate, filtered, and concentrated to provide a mixture of product and starting material, which is resubmitted to the above conditions (THF used instead of DMF). Purification of the resultant crude material by flash chromatography (silica gel; ethyl acetate/methanol (4/1)) provides the product. Recrystallization from hot ethyl acetate/hexane gives the desired title compound, mp 233°-234°; IR (mineral oil) 1719, 1615, 1607, 1388, 1270, 1128 cm-1 ; NMR (CDCl3) 8.67, 7.95-8.15, 7.65-7.9, 7.54, 4.7-4.85, 3.35-3.55, 2.4-3.1, 1.68, 1.22 and 0.85-1.05 δ; MS (El, m/e) 408, 351, 335, 307, 239, 195 and 113.

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