Palladium-Catalyzed Asymmetric Cascade Intramolecular Cyclization/Intermolecular Michael Addition Reaction of Allenyl Benzoxazinones with 1-Azadienes

Abstract

We herein designed and synthesized allenyl benzoxazinones of a novel type, which were then involved in a Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition reaction with 1-azadienes. A broad range of chiral C2-functionalized quinoline derivatives were afforded in moderate to good yields (up to 93%) with high enantioselectivities (up to 93% ee) in this reaction.

Facile Synthesis of Quinoline-Substituted 3-Hydroxy-2-oxindoles and 3-Amino-2-oxindoles via a Palladium-Catalyzed Cascade Intramolecular Cyclization/Intermolecular Nucleophilic Addition Reaction

“…In our prior work, we achieved a Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition reaction of 1-azadiene with allenyl benzoxazinone. This reaction also involved the formation of an η 2 -Pd 0 complex in the presence of a palladium catalyst (Scheme c) . Building upon our work and drawing inspiration from Chen’s group reports, we envisioned that allenyl benzoxazinone could readily form highly active η 2 -complexes in the presence of a palladium catalyst and subsequently engage in cascade intramolecular cyclization/intermolecular nucleophilic addition reactions with ketones and ketimines.…”

“…This reaction also involved the formation of an η 2 -Pd 0 complex in the presence of a palladium catalyst (Scheme 2c). 10 Building upon our work and drawing inspiration from Chen's group reports, we envisioned that allenyl benzoxazinone could readily form highly active η 2 -complexes in the presence of a palladium catalyst and subsequently engage in cascade intramolecular cyclization/intermolecular nucleophilic addition reactions with ketones and ketimines. Furthermore, quinoline is a privileged organic scaffold found in various natural products and pharmaceuticals.…”

Advancements in Asymmetric Catalytic Approaches Involving Benzoxazinone Derivatives

“…[72] Almost simultaneously, Wang, Yuan and co-workers developed a Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition reaction between 1-azadienes 108 and allenyl benzoxazinones 4 generated form 2 -Pd(0) complex as Michael donor, accessing to a range of chiral C2functionalized quinoline derivatives 109 in good yields (up to 93%) with high enantioselectivities (up to 93% ee) (Scheme 44). [73] Remarkably, the desirable addition product could not be achieved as the tosyl-protected allenyl benzoxa zinone employed under the optimized conditions, which indicated that the free NÀ H was crucial to forming the η 2 -Pd(0) intermediate.…”

Asymmetric 2,4-Dienylation/[4 + 2] Annulation Cascade to Construct Fused Frameworks via Auto-Tandem Palladium Catalysis

“…Recently, our group established that palladium(0) could form η 2 -complexes with 1,3-dienes and act as a π-Lewis base catalyst to promote their vinylogous attack on imines or carbonyls in a Friedel–Crafts reaction pattern . By utilizing the multiple catalytic capacity of palladium, we further developed the auto-tandem assemblies of 2,4-dienyl carbonates and o -aminoarylimines, finally realizing divergent synthesis via ligand control (Scheme b) .…”