Palladium-Catalyzed Arylic/Allylic Aminations: Permutable Domino Sequences for the Synthesis of Dihydroquinolines from Morita–Baylis–Hillman Adducts

An efficient palladium-catalyzed synthesis of 1,2-dihydroquinolines has been developed via the reaction between anilines and Morita–Baylis–Hillman adducts derived from <i>o</i>-bromobenzaldehyde. This new Pd(0)-catalyzed pseudo-domino type I sequence involves a Buchwald–Hartwig arylic amination and an allylic amination. When starting from an <i>o</i>-bromo allylic alcohol, the chronology is arylic amination/allylic arylation. However, the sequence reverses when the reaction is performed on the corresponding <i>o</i>-bromo allylic acetate

Pd-Catalyzed Direct C–H Alkenylation and Allylation of Azine <i>N</i>‑Oxides

A Pd-catalyzed direct C₂-alkenylation of azine <i>N</i>-oxides with allyl acetate is disclosed. The products are formed through an allylation/isomerization cascade process. The use of a tri-<i>tert</i>-butylphosphonium salt as the ligand precursor and KF is mandatory for optimal yields. When cinnamyl acetate is used, the same catalytic system promotes C₂-cinnamylation of the azine <i>N</i>-oxide without subsequent isomerization. A mechanism is proposed on the basis of experimental studies and DFT calculations

Opening the Way to Catalytic Aminopalladation/Proxicyclic Dehydropalladation: Access to Methylidene γ‑Lactams

A new aerobic intramolecular palladium­(II)-based catalytic system that triggers aminopalladation/dehydropalladation of <i>N</i>-sulfonyl­alkenylamides to give the corresponding methylidene γ-lactams has been identified. Use of triphenylphosphine and chloride anion as ligands is mandatory for optimal yields, and molecular oxygen can be used as the sole terminal oxidant. Scope and limitations of the methods are described. A mechanism is proposed on the basis of experimental results as well as density functional theory calculations

Opening the Way to Catalytic Aminopalladation/Proxicyclic Dehydropalladation: Access to Methylidene γ‑Lactams

A new aerobic intramolecular palladium­(II)-based catalytic system that triggers aminopalladation/dehydropalladation of <i>N</i>-sulfonyl­alkenylamides to give the corresponding methylidene γ-lactams has been identified. Use of triphenylphosphine and chloride anion as ligands is mandatory for optimal yields, and molecular oxygen can be used as the sole terminal oxidant. Scope and limitations of the methods are described. A mechanism is proposed on the basis of experimental results as well as density functional theory calculations

Palladium-Catalyzed [3 + 2]-C–C/N–C Bond-Forming Annulation

The synthesis of bi- and tricyclic structures incorporating pyrrolidone rings is disclosed, starting from resonance-stabilized acetamides and cyclic α,β-unsaturated-γ-oxycarbonyl derivatives. This process involves an intermolecular Tsuji–Trost allylation/intramolecular nitrogen 1,4-addition sequence. Crucial for the success of this bis-nucleophile/bis-electrophile [3 + 2] annulation is its well-defined step chronology in combination with the total chemoselectivity of the former step. When the newly formed annulation product carries a properly located <i>o</i>-haloaryl moiety at the nitrogen substituent, a further intramolecular keto α-arylation can join the cascade, thereby forming two new cycles and three new bonds in the same synthetic operation

Pd-Containing Organo­polyoxo­metalates Derived from Dawson Polyoxo­metalate [P₂W₁₅V₃O₆₂]^9–: Lewis Acidity and Dual Site Catalysis

Grafting of a palladium complex to the Dawson vanado­tungstate polyanion [P₂W₁₅V₃O₆₂]^9– via an organic ligand generates a large family of pincer-type hybrid polyoxometalates. The palladium-POM derivatives have dual catalytic properties. Unlike their parent inorganic polyanions, they catalyze allylations while retaining their oxidant character, which leads to single-pot dual site catalysis. This opens a new route for multicatalytic reactions