Dichloromethane → Diisopropylethylamine

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Reaction Steps

As described in diagram G, the derivative (26) can be alkylated in the presence of a strong base such as potassium tertbutylate, by an α-chloroester derivative, in an aprotic polar solvent such as dimethylformamide at a temperature of 0-20° C. for 0.5-2 hours, in order to produce compound (27). The derivative (27) can be optionally alkylated in the presence of a strong base such as sodium hydride and an alkylating agent such as an alkyl iodide in an aprotic solvent such as dimethylformamide at a temperature of 0-20° C. for 1-4 hours, in order to produce compound (28). The ester (28) can be saponified in the presence of an inorganic base such as lithium or potassium hydroxide in a mixture of polar solvents such as water and methanol at a temperature of 20-80° C. for 1-6 hours. The resultant carboxylic acid (29) can be coupled with a primary or secondary amine in the presence of a coupling agent such as diisopropylcarbodiimide (DIC), dicyclohexylcarbodiimide (DCC), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) or carbonyldiimidazole (CDI), with or without 1-hydroxybenzotriazole (HOBt) in an inert organic solvent such as methylene chloride, tetrahydrofuran or dimethylformamide at ambient temperature for 3 to 24 hours. Alternatively the acid (29) can be treated with thionyl or oxalyl chloride in an aprotic solvent such as dichloromethane or toluene at a temperature of 40-60° C. for 2-16 hours then the acid chloride thus obtained can react with a primary or secondary amine, in the presence of a tertiary base such as triethylamine, diisopropylethylamine in an aprotic solvent such as dichloromethane or tetrahydrofuran at a temperature of 0-20° C. over 0.5-4 hours in order to produce the amide (30). Treatment of the fluorinated or chlorinated derivative (30) with a primary amine in the presence of an inorganic base such as caesium or potassium carbonate in an inert organic solvent such as dimethylformamide or acetonitrile at a temperature of 20-100° C. for 2 to 48 hours leads to the derivative (31). The nitro function of compound (31) is reduced by treatment with tin chloride dihydrate in an inert solvent such as ethyl acetate or dimethylformamide at a temperature of 60-80° C. for 3 to 15 hours, or by catalytic hydrogenation in the presence of 10% palladium on carbon in an inert solvent such as methanol, ethanol, ethyl acetate or a mixture of these solvents, at a temperature of 18-25° C., for 2 to 8 hours in order to produce the dianiline (32). The derivative (32) is then treated with an isothiocyanate in the presence of a coupling agent supported or not supported on a resin such as diisopropylcarbodiimide or dicyclohexylcarbodiimide or N-methylcyclohexylcarbodiimide N-methyl polystyrene resin in an inert solvent such as tetrahydrofuran, methylene chloride, or chloroform at a temperature of 20-70° C. for 2 to 72 hours in order to produce the derivative (33). Alternatively, the derivative (32) can be treated with an isothiocyanate in an inert solvent such as tetrahydrofuran, methylene chloride, chloroform or ethanol at a temperature of 20-80° C. for 1-16 hours then the resultant thiourea can be treated with methyl iodide or yellow mercury (II) oxide in the presence of a catalytic quantity of sulphur in a polar solvent such as methanol or ethanol for 2 to 24 hours at a temperature of 20-80° C. in order to produce (33). Compound (6) can be isolated either by flash chromatography on silica gel, or by the addition to the reaction mixture of a nucleophilic reagent supported on a polymer such as for example an aminomethylpolystyrene resin and/or an electrophilic reagent supported on a polymer such as for example methylisothiocyanate-polystyrene resin, followed by filtration and evaporation of the filtrate.

Provenance & Evidence