Radical bromination of methyl 3-methoxy-4-methylbenzoate (I) using N-bromosuccinimide and azobisisobutyronitrile gave benzyl bromide (II), which was treated with pyrrolidine to afford the tertiary amine (III). Hydrolysis of the methyl ester group of (III) with LiOH provided carboxylic acid (IV), which was converted to acid chloride (V) upon treatment with SOCl2.

Condensation of 4-benzyloxybenzaldehyde (VI) with N,N-dimethylthioformamide in the presence of LDA in THF at -78 C provided the alpha-hydroxythioacetamide (VII), which was cyclized with methanesulfonic acid to yield benzothiophene (VIII). Subsequent acylation of (VIII) with the intermediate acid chloride (V) in boiling chlorobenzene provided ketone (IX). 4-Bromophenol (X) was protected as the triisopropylsilyl ether using triisopropylsilyl trifluoromethanesulfonate and imidazole, and then converted to the corresponding Grignard reagent (XI) with Mg in THF. Displacement of the dimethylamino group from benzothiophene (IX) by Grignard reagent (XI) furnished the 2-arylbenzothiophene (XII), which was desilylated with tetrabutylammonium fluoride to give (XIII). The ketone function of (XIII) was then reduced by means of LiAlH4 to yield (XIV).

Subsequent Mitsunobu condensation of (XIV) with N-trityl-L-serine methyl ester (XV) in the presence of DEAD and PPh3 produced the serine ether (XVI). Deprotection of the trityl group of (XVI) by means of trifluoroacetic acid and triethylsilane, followed by transfer hydrogenolysis of the benzyl ether with ammonium formate and Pd/C provided the deprotected intermediate (XVII). Finally, reduction of the ester group of (XVII) with LiAlH4 yielded the title compound.