Highly Stereoselective Construction of β,β-Diaryl-α-Branched Ketones by the Chiral Primary Amine-Catalyzed Asymmetric Retro-Claisen Reaction.

Highly diastereo- and enantioselective retro-Claisen reaction of β-diketones with o-quinone methides has been developed by chiral primary amine catalysis. This reaction allows for efficient synthesis of chiral β,β-diaryl-α-branched ketones in moderate to good yields with excellent stereoselectivities. The reaction occurs via a tandem sequence of benzylic C-C bond formation, C-C bond cleavage, and stereospecific enamine protonation. This strategy uses o-quinone methides as diaryl precursors and features a broad substrate scope, mild conditions, and a high degree of stereocontrol.