合成路线1

The cyclization of pyridine-3-carbaldehyde (I) with L-cysteine (II) gives 2-(3-pyridyl)thiazolidine-4(R)-carboxylic acid (III), which is finally condensed with 1-(3-methyl-3-phenylbutyl)piperazine (IV) by means of DCC and HOBT In DMF. The intermediate 1-(3-methyl-3-phenylbutyl)piperazine (IV) has been obtained as follows: The reduction of 3-methyl-3-phenylbutyric acid (IV) with LiAlH4 in THF gives the corresponding butanol (V), which is treated with refluxing 48% HBr to yield the 3-methyl-3-phenylbutyl bromide (VI). The condensation of (VI) with piperazine-1-carboxylic acid ethyl ester (VII) by means of K2CO3 in 2-butanone gives 4-(3-methyl-3-phenylbutyl)piperazine-1-carboxylic acid ethyl ester (VIII), which is decarboxylated with NaOH in refluxing ethanol.