Alkylation of 3-chlorophenylacetic acid (I) with allyl bromide (II) using lithium hexamethyldisilazide provided racemic (III), which was resolved by recrystallization of the corresponding diastereoisomeric salts with (S)-alpha-methylbenzylamine. The desired (S)-carboxylic acid (IV) was converted to acid chloride and then treated with methylamine yielding amide (V). Reduction of (V) with LiAlH4 gave amine (VI), which was acylated with benzenesulfonyl chloride to afford sulfonamide (VII). A two-step oxidation of the allyl group of (VII) with osmium tetroxide and N-methylmorpholine N-oxide, followed by sodium periodate cleavage of the resulting diol produced aldehyde (VIII). Reductive condensation of (VIII) with spiro piperidine (IX) using NaBH(OAc)3 furnished adduct (X). Final oxidation of the sulfide group of (X) with one equivalent of Oxone(r) afforded the title sulfoxide.

Alkylation of 3-chlorophenylacetic acid (I) with allyl bromide (II) using lithium hexamethyldisilazide provided racemic (III), which was resolved by recrystallization of the corresponding diastereoisomeric salts with (S)-alpha-methylbenzylamine. The desired (S)-carboxylic acid (IV) was converted to acid chloride and then treated with methylamine yielding amide (V). Reduction of (V) with LiAlH4 gave amine (VI), which was acylated with benzenesulfonyl chloride to afford sulfonamide (VII). A two-step oxidation of the allyl group of (VII) with osmium tetroxide and N-methylmorpholine N-oxide, followed by sodium periodate cleavage of the resulting diol produced aldehyde (VIII). Reductive condensation of (VIII) with spiro piperidine (IX) using NaBH(OAc)3 furnished adduct (X). Final oxidation of the sulfide group of (X) with one equivalent of Oxone(r) afforded the title sulfoxide.