Addition reactions on coordinated olefinic ligands. III. trans. Addition of a nucleophile to a platinum(II) coordinated simple olefin

Abstract

It is well known1 that coordination to platinumgroup metals yields simple unsaturated hydrocarbons susceptible to attack by nucleophiles. Studies of the mechanism of this type of reactions have been carried out, mainly on catalytic systems.2 Noncatalytic processes have also been reported and observations on the mechanism presented3 in some cases. A double role has been generally attributed to the metal,4 which is assumed to activate both the unsaturated substrate and the nucleophile, via coordination.

Transition‐Metal‐Catalyzed Hydroamination Reactions

“…Alkyl-substituted amines present a persistent challenge in this chemistry, as the nucleophilic nature of these amine substrates result in systems that do not realize catalytic turnover, and consequently, well-characterized examples of zwitterionic products resulting from nucleophilic addition to π-coordinated ethylene are well known [88,112,160,144,[161][162][163][164]. These species may result in the stoichiometric formation of ethylated amines upon quenching of the reaction [161,162], but limited catalytic reactivity has been obtained [88,163].…”

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

“…[19] The reaction was proven to be stereospecific by using cis-1,2-dideuterioethylene; no cis/trans isomerization accompanied the reversible addition. [20] A key observation from an elegant demonstration by Panunzi et al [21] was that diethylamine adds to a diastereomerically resolved platinum complex of the prochiral olefin 1-butene to give, after protonolysis, only (S)-N,N'-diethyl-sec-butylamine, the product of Markovnikov addition with anti stereochemistry [Eq. (3)].…”

“…The reaction was proposed to proceed through an outer-sphere mechanism, involving nucleophilic attack of amine on the coordinated alkene, as had been previously demonstrated in several stoichiometric studies. [11,12,21,69] Protonolysis of the resulting PtÀC bond would give the cyclic amine product and regenerate the catalyst (Scheme 9).…”

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

“…[19] In Untersuchungen mit cis-1,2-Dideuterioethylen wurde gefunden, dass die Reaktion stereospezifisch verläuft; bei der reversiblen Addition wurde keine cis-trans-Isomerisierung beobachtet. [20] Ein ganz entscheidender Befund stammte von Panunzi et al, [21] die zeigen konnten, dass die Addition von Diethylamin an einen diastereomerenreinen Platinkomplex des prochiralen Olefins 1-Buten nach Protonolyse ausschließlich das (S)-N,N'-Diethyl-sec-butylamin (das Produkt der Markownikoff-Addition mit anti-Konfiguration) liefert [Gl. (3)].…”

“…(11)]. [67] Eine nachfolgende Arbeit zeigte, [68] [11,12,21,69] Die Protonolyse der entstehenden Pt-CBindung führt zum cyclischen Aminprodukt und regeneriert den Katalysator (Schema 9).…”