Recoverable chiral sulfoxide: remote asymmetric induction in Lewis acid-promoted Diels–Alder reaction of chiral sulfinyl-substituted pyrrolyl α,β-unsaturated enones

Abstract

1-[2-(p-Tolylsulfinyl)]pyrrolyl α,β-unsaturated enones served as efficient dienophiles in the Diels–Alder reaction, where the use of aluminium chloride or a lanthanide triflate effected the cycloaddition with cyclopentadiene, affording the endo adduct with high diastereoselectivity. In particular, for the sulfinyl dienophile, the chiral auxiliary (i.e. the sulfinyl pyrrole) was recovered after use without any loss of optical purity.