Intramolecular Pd-Catalyzed Carboetherification and Carboamination. Influence of Catalyst Structure on Reaction Mechanism and Product Stereochemistry

Abstract

The intramolecular Pd-catalyzed carboetherification of alkenes affords 2-indan-1-yltetrahydrofuran products in moderate to good yield with good to excellent levels of diastereoselectivity. The stereochemical outcome of these reactions is dependent on the structure of the Pd-catalyst. Use of PCy 3 or P[(4-MeO)C 6 H 4 ] 3 as the ligand for Pd leads to syn-addition of the arene and the oxygen atom across the double bond, whereas use of (±)-BINAP or DPP-Benzene affords products that result from anti-addition. The catalyst-induced change in stereochemistry is likely due to a change in reaction mechanism. Evidence is presented that suggests the syn-addition products derive from an unprecedented transannular alkene insertion of an 11-membered Pd(Ar)(OR) complex. In contrast, the anti-addition products appear to arise from Wacker-type anti-oxypalladation. Studies on analogous Pd-catalyzed intramolecular carboamination reactions, which afford 2-indan-1-ylpyrrolidines that result from syn-addition, are also described.

Electrophilic Activation of Alkenes by Platinum(II): So Much More Than a Slow Version of Palladium(II)

“…In some cases, stereochemical evidence has been provided for syn addition [24,[36][37][38][39][40][41][42][43] and in others, for anti addition. [37,39,44,45] Although a detailed discussion of these observations is outside the scope of this review, it is important to note that for palladium-catalyzed additions of carbon, nitrogen, and oxygen nucleophiles to C=C bonds, both syn and anti addition mechanisms appear possible, and the catalytic conditions determine which pathway is preferred. For platinum catalysis one might expect outer-sphere attack to be kinetically favored over the coordination/insertion pathway because of the much slower rates of ligand substitution for platinum relative to palladium.…”

Iridium-Catalyzed, Intermolecular Hydroetherification of Unactivated Aliphatic Alkenes with Phenols

“…Palladium-catalyzed amination reactions now thought to occur by a migratory insertion step include carboaminations, [83][84][85][86] oxidative aminations, [87][88][89] chloroaminations, [90] aminoacetoxylations, [91] diaminations, [92] and hetero-Heck-type transformations. [93] In some cases, stereochemical evidence for syn aminopalladation by migratory insertion has been gained.…”

Elektrophile Aktivierung von Alkenen mit Platin(II): sehr viel mehr als eine langsame Variante von Palladium(II)

“…In einigen Fällen wurden Beweise für eine syn-Addition, [24,[36][37][38][39][40][41][42][43] in anderen Fällen für eine anti-Addition erhalten. [37,39,44,45] Auf eine ausführliche Diskussion müssen wir hier verzichten, es soll aber angemerkt sein, dass für Palladium-katalysierte Additionen von Kohlenstoff-, Stickstoff-und Sauerstoff-Nucleophilen an C = CBindungen sowohl syn-als auch anti-Additionen möglich erscheinen und offenbar die katalytischen Bedingungen den Ausschlag geben, über welchen Mechanismus die Reaktion verläuft. Für Platinkatalysen kann man annehmen, dass der Outer-Sphere-Angriff aus kinetischen Gründen gegenüber der Koordination/Insertion begünstigt ist, weil Pt generell langsamere Ligandensubstitutionen eingeht als Pd.…”