合成路线1

This compound can be obtained by three related ways: 1) The condensation of 3-cyclopentyloxy-4-methoxybenzaldehyde (I) with diethyl malonate (II) by means of piperidine in refluxing acetic acid gives diethyl 3-cyclopentyloxy-4-methoxybenzylidenemalonate (III), which is treated with nitromethane and tetramethylguanidine (TMG) yielding diethyl 2-[1-(3-cyclopentyloxy-4-methoxyphenyl)-2-nitroethyl]malonate (IV). The reductocyclization of (IV) with H2 over Raney Ni in hot methanol gives ethyl 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-oxopyrrolidine-3-carboxylat (V). Finally, this compound is hydrolyzed and decarboxylated. 2) The reaction of malonate (III) with KCN in ethanol at 60 C gives ethyl 3-cyano-3-(3-cyclopentyloxy-4-methoxyphenyl)propionate (VI), which is reduced with H2 over PtO2 in acetic acid yielding ethyl 4-amino-3-(3-cyclopentyloxy-4-methoxyphenyl)butanoate (VII). Finally, this compound is hydrolyzed and cyclized. 3) The reaction of malonate (III) with KNC in refluxing ethanol gives 3-cyano-3-(3-cyclopentyloxy-4-methoxy)propanoic acid (VIII), which is reduced with H2 over PtO2 as before yielding 4-amino-3-(3-cyclopentyloxy-4-methoxyphenyl)butanoic acid (IX). Finally, this compound is cyclized.