Maleic Acid → 3-(4-Allyl-1-piperazinyl)-3-(4-methoxyphenylimino)-1-phenyl-1-propyne dimaleate

Participants

Reaction Conditions

Reaction Steps

3-(4-Allyl-1-piperazinyl)-3-(4-methoxyphenylimino)-1-phenyl-1-propyne can be prepared in the following manner: to a solution of N-(dichloromethylene)-p-anisidine (59 g) in ethyl ether (600 cc), a solution of 1-allylpiperazine (72 g) in tetrahydrofuran (450 cc) is added at a temperature of about 20° C. and in the course of 20 minutes, and stirring is continued for a further 30 minutes at a temperature of about 20° C. The precipitate which is formed is separated by filtration. The solution thereby obtained is added in the course of 3 minutes, at a temperature of about -65° C., to a solution of phenylethynyllithium in tetahydrofuran (600 cc), obtained by reacting phenylacetate (30.6 g) dissolved in tetrahydrofuran (600 cc) with a 1.6M solution (187 cc) of n-butyllithium in hexane at a temperature of about 20° C. The reaction mixture is allowed to warm up to a temperature of about 20° C. and then poured onto crushed ice (500 g). The aqueous phase is decanted and washed with ethyl ether (3×500 cc). The ether fractions are combined, washed with distilled water (250 cc), dried over anhydrous magnesium sulphate, filtered and then evaporated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 40° C. The residue obtained in dissolved in methylene chloride (200 cc) and the solution is poured into silica (2 kg) contained in a column 8 cm in diameter. Elution is performed with mixtures of methylene chloride and ethyl acetate (4×1 liter containing, respectively, 10%, 20%, 30% and 40% of ethyl acetate); the corresponding eluates are rejected. Elution is then performed with a mixture of methylene chloride and ethyl acetate (50:50 by volume) (3 liters); the corresponding eluate is evaporated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 40° C. The residue obtained is dissolved in boiling acetonitrile (175 cc); maleic acid (35 g) dissolved in boiling acetonitrile (350 cc) is added to the solution. After the mixture is cooled to a temperature of about 20° C., the precipitate formed is separated by filtration. After recrytallization in acetonitrile (550 cc), 3-(4-allyl-1-piperazinyl)-3-(4-methoxyphenylimino)-1-phenyl-1-propyne dimaleate (58.3 g), m.p. 180° C., is thereby obtained.

Provenance & Evidence