Tyramine → Ethyl N-[2-(4-hydroxyphenyl)ethyl]carbamate

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Reaction Steps

According to scheme 1, ethyl chloroformate is added to a solution of tyramine (1), sodium hydroxide, and water to produce the [2-(4-hydroxy-phenyl)-ethyl]carbamic acid ethyl ester (2). The carbamate is treated with cesium carbonate and 4-fluorobenzonitrile in DMF to yield the corresponding biarylether 3. The nitrile functionality of the biaryl; ether 3 is converted to the N-acyl compound 4 by reaction with methyllithium followed by hydrolysis in aqueous sulfuric acid. The N-acyl compound 4 is converted to the acetate 5 by oxidation with m-chloroperbenzoic acid (MCPBA) in a suitable solvent. The acetate 5 is reduced with lithium aluminum hydride to afford the compound 4-[4-(2-methylamino-ethyl)-phenoxy]-phenol (6). The compound 6 is treated with benzaldehyde in the presence of sodium triacetoxyborohydride to produce the reductive amination product 4-{4-[2-(benzyl-methyl-amino)-ethyl]-phenoxy}-phenol 7 of formula I. Compounds of formula I wherein D is acetate and q is 0, may also be prepared according to scheme 2 below.

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