Palladium-Catalyzed Inverse and Normal Dehydrogenative Aza-Morita-Baylis-Hillman Reactions with γ,δ-Unsaturated Compounds.

σ-Lewis base-catalyzed regio- and enantioselective aza-Morita-Baylis-Hillman (MBH) reaction of α,β,γ,δ-unsaturated systems remains a challenge due to the intrinsic covalent activation mode. Here we demonstrate that a Pd complex can mediate the dehydrogenative reaction of γ,δ-unsaturated compounds to give corresponding electron-poor dienes, which further undergo δ-regioselective umpolung Friedel-Crafts-type addition to imines via auto-tandem Pd -π-Lewis base catalysis. After β-H elimination of in situ formed Pd -complexes, unprecedented and chemically inverse aza-MBH-type adducts are finally furnished with fair to outstanding enantioselectivity, and a diversity of functional groups and both ketimine and aldimine acceptors can be well tolerated.

Use of (,)-Dienoic Acids as Switchable (,)- and (,)-Dienyl Anion Surrogates via Ligand-Controlled Palladium Catalysis.

Carboxylic acids are not readily applied as carbon-based nucleophiles due to their intrinsic acidic group. Here, we demonstrate that free (,)-2,4-dienoic acids form electron-neutral and highest occupied molecular orbital-raised η-complexes with Pd(0) and undergo Friedel-Crafts-type additions to imines with exclusive α-regioselectivity, giving formal dienylated products after decarboxylation. Unusual and switchable (,)- and (,)-selectivity, along with excellent enantioselectivity, is achieved via ligand-controlled outer-sphere or inner-sphere reaction modes, respectively, which are well supported by comprehensive density functional theory calculation studies.

Formal nucleophilic pyrrolylmethylation palladium-based auto-tandem catalysis: switchable regiodivergent synthesis and remote chirality transfer.

Although nucleophilic benzylation-type reaction to introduce various aromatic systems into molecules has been widely explored, the related pyrrolylmethylation version remains to be disclosed. Reported herein is a palladium-catalysed multiple auto-tandem reaction between Ts propargylamines, allyl carbonates and aldimines in the presence of an acid, proceeding through sequential allylic amination, cycloisomerisation, vinylogous addition and aromatisation steps. A diversity of formal pyrrolylmethylated amine products were finally furnished efficiently.