Stereoselective Synthesis of Conjugated Di- and Trienamides via a Dienolate Enabled Anionic Cascade

We report a stereoselective synthesis of conjugated di- and trienamides from the direct one pot γ-selective union of a dienolate and chiral nonconjugated and conjugated sulfinyl imines, respectively. This class of anionic cascades was uncovered as part of efforts to challenge the steric limitations of an anionic asymmetric amino-Cope rearrangement platform. Reaction scope studies have uncovered the substitution patterns essential for starting chiral tri- and Z-disubstituted conjugated and nonconjugated sulfinyl imines to be matched for the anionic cascade. Mechanistic studies indicate that, following an initial γ-dienolate Mannich attack, an intermediate 5,6-dihydropyridin-2(1H)-one is formed and then ring-opened.