Lithiation of 6-bromo-2,2-dimethyl-2H-1-benzopyran (I), followed by treatment with sulfur dioxide, gave the sulfinic acid (II), which was subsequently chlorinated to sulfonyl chloride (III) employing SO2Cl2. Condensation of sulfonyl chloride (III) with aniline furnished the target N-phenyl sulfonamide (IV).

In a different method, sodium 4-hydroxybenzenesulfonate (V) was converted to the sulfonyl chloride (VI) upon treatment with thionyl chloride in hot 1,2-dichloroethane. Reaction of acid chloride (VI) with aniline provided sulfonamide (VII). Alkylation of the phenolic hydroxyl group of (VII) with 3-chloro-3-methyl-1-butyne (VIII) in the presence of DBU and CuCl gave the propargyl ether (IX), which was then cyclized to benzopyran (IV) under Claisen rearrangement conditions.

Asymmetric epoxidation of benzopyran (IV) using NaOCl in the presence of the chiral catalyst (S,S)-(+)-N,N'-bis(3,5-di-t-butylsalicylidene)-1,2-cyclohexanediaminomanganese (III) chloride produced the desired (S,S)-epoxide (X). The title compound was then obtained by oxirane ring opening in (X) with the lithium derivative of 2-piperidinone (XI) in hot THF.