9H-Pyrido(2,3-b)indole → Dicyclohexylcarbodiimide

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Reaction Steps

Method for the preparation of compound 19 [isopentyl 2-(2,6-dimethyl-3,4-dihydro-1H-pyrido[3,4-b]indol-9(2H)-yl)acetate]:p-tolylhydrazine is alkylated with ethyl 2-bromoacetate to give the substituted phenylhydrazine, ethyl 2-(1-p-tolylhydrazinyl)acetate (III). The reaction of III with 4,4-dimethoxy-N-methylbutan-1-amine gives the indole derivative ethyl 2-(5-methyl-3-(2-(methylamino)ethyl)-1H-indol-1-yl)acetate (V). Effecting the indole to standard Pictet Spingler conditions with formaldehyde gives the 3-carboline intermediate (VI) ethyl 2-(2,6-dimethyl-3,4-dihydro-1H-pyrido[3,4-b]indol-9(2H)-yl)acetate. Following treatment of VI with base the acid (VII) 2-(2,6-dimethyl-3,4-dihydro-1H-pyrido[3,4-b]indol-9(2H)-yl)acetic acid is obtained. The treatment of this acid with DCC or other standard coupling reagents with 3-methylbutan-1-ol gives compound 19 isopentyl 2-(2,6-dimethyl-3,4-dihydro-1H-pyrido[3,4-b]indol-9(2H)-yl)acetate. After the successful synthesis of the compound, purification can be achieved using standard normal phase or reverse phase methods.

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