Firm Evidnce for Cis-Aminopalladation in the Reaction of 1-Aminohexatrienes With Palladium Dichloride

Abstract

The reaction of PdCl2(PhCN)2 with ethyl α-N-acetyl-β-(4,6-dimethylbenzofuran-2-yl)acrylate, having a Z-propenyl group at 2-position of benzofuran ring, gave an azepine derivative, whereas its E-isomer afforded a Pd-σ-complex having azepine skeleton. Configurational assignment of the σ-complex, accomplished by methoxycarbonylation, clearly demonstrates that this intramolecular aminopalladation proceeds via cis-aminopalladation.

Palladium-Catalyzed Intramolecular Diamination of Acrylic Esters Using Sulfamates as Nitrogen Source

“…Treatment of the isolated aminobrominated intermediate 5 with base in DMF gave the expected product 3a as single isomer in 92% isolated yield. This reaction outcome suggests that the present diamination reaction proceeds through a catalytic cycle of syn -aminopalladation ,,,, to A followed by copper-mediated transient palladium oxidation with concomitant C–Br bond formation . This latter step proceeds with clean S N 2 chemistry leading to inversion of configuration at carbon.…”

Palladium(II)-Catalyzed Alkene Functionalization via Nucleopalladation: Stereochemical Pathways and Enantioselective Catalytic Applications

“…31a Later, a report by Taniguchi and co-workers showed that enamide 46 underwent aminopalladation to furnish isolable Pd-alkyl intermediate 47 (eq 6). 33 The anti relationship between Pd and the β -hydrogen precludes β -hydride elimination from occurring, and the product stereochemistry supports a cis -aminopalladation mechanism. These early studies, which established a foundation for future investigations of alkene amination, were based upon stoichiometric reactions and therefore the insights do not necessarily apply to catalytic systems.…”

“…Evidence for trans attack of the coordinated alkene was provided by formation of cyclometalated Pd−alkyl intermediate 44 , whose stereochemistry was established by NMR spectroscopic studies or by reduction with LiAlD 4 to form stereospecifically deuterated product 45 (Scheme ) . Later, a report by Taniguchi and co-workers showed that enamide 46 underwent aminopalladation to furnish isolable Pd−alkyl intermediate 47 (eq ) . The anti relationship between Pd and the β-hydrogen precludes β-hydride elimination from occurring, and the product stereochemistry supports a cis -aminopalladation mechanism.…”

The syn/anti‐Dichotomy in the Palladium‐Catalyzed Addition of Nucleophiles to Alkenes

“…The first amidopalladation, analogous to alkoxypalladation, was explored in a stoichiometric experiment with enamide 116 and found to produce the azepine derivative 117 with the new C=N and C=Pd bonds related in a cis -fashion, which correspond to syn -addition (Scheme 31). [ 50 ]…”