E-mail: sami. E-mail: martin. The reactivity of sodium phosphaethynolate Na OCP towards various Mayr's reference electrophiles was investigated using conventional UV-visible and laser-flash photolysis techniques. Product studies of these reactions demonstrate the formation of secondary as well as tertiary phosphines. The mechanism of this unprecedented phosphorus-atom transfer reaction is thoroughly discussed, with key intermediates successfully isolated and characterized.
Importantly, some bulky secondary phosphine oxides synthesized using this approach, have demonstrated high efficiency as ligands in the Suzuki coupling reaction. Their results indicated a lower intrinsic barrier for the oxygen attack, highlighting the kinetic preference of oxygen attacks. The objective is to gain deeper insights into the factors controlling the reactivity of this anion, which is crucial for unlocking its synthetic potential Table 1. In previous investigations, Mayr et al. Our investigation commences with the synthesis of sodium phosphaethynolate using a protocol outlined in Scheme 2.
As ion pairing should not be important under the low concentrations used in the kinetic studies, [Na OCP ] dioxane 2. Rates of those reactions were determined either by studying the kinetics of laser-flash photolytically generated benzhydrylium ions or conventional UV-visible spectrophotometry using stable quinone methides or benzhydrylium ions.
Following previous investigations by Mayr et al. To investigate the role of the counterion on the reactivity of Na OCP with benzhydrylium ions, reactions of the former with the carbocation 1n were studied in the presence of the crown ether crown The effect of dioxane on the reactivity has also been addressed, and we found that the reaction of dioxane-free Na OCP with 1n react similarly as [Na OCP ] dioxane 2.
In accordance with eqn 1 , Fig. It is important to emphasize the excellent linearity observed in the correlation log k 2 vs. E , indicating that the rate-determining step does not change throughout this reaction series. This implies that the same nucleophile terminus center attacks all electrophiles. The next critical step involves determining whether the identified nucleophilicity parameters align with the attack on oxygen or phosphorus.
