合成路线1

The decarboxylative hydrolysis of 2,4-dimethoxycarbonyl-3-(3-phenylpropyl)cyclopentanone (XIV) with HCl in acetic acid gives 4-carboxy-3-(3-phenylpropyl)cyclopentanone (XV), which by reaction with oxalyl chloride (B) is converted into the corresponding acyl chloride (XVI). The Arndt-Eistert carbon homologation in (XVI) with diazomethane and silver benzoate (C) in methanol affords 4-(methoxycarbonylmethyl)-4-(3-phenylpropyl)cyclopentanone (XVIIa), which is dehydrogenated by the sequence of reactions: N-bromosuccinimide and sodium selenofenolate (D) [to obtain intermediates (XVIIb) and (XVIIc), respectively], followed by reaction with hydrogen peroxide to give 4-(methoxycarbonylmethyl)-3-(3-phenylallyl)cyclopentanone (XVIIIa). Oxidation of (XVIIIa) first with osmium tetroxide and then with Jones reagent (CrO3) [to obtain intermediates (XVIIIb) and (XVIIIc), respectively], followed by methylation of (XVIIIc) with CH2N2 affords 3,4-di(methoxycarbonylmethyl)cyclopentanone (XIX), which is ketalized in the usual way to the ketal (XX). Finally, this compound is submitted to a Dieckmann condensation with sodium methoxide in DMS to yield the protected ketoester (IVa), the methyl ester analogue of the compound (IV) obtained in scheme 09083302a. This compound can then be used instead of (IV) in scheme 09083302a.