An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

Abstract

Aqueous Mizoroki–Heck coupling reactions under microwave irradiation (MW) were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone) (PVP). Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The reaction was carried out in a short reaction time and with low catalyst loading, leading to high turnover frequency (TOFs of the order of 100 h−1). The advantages like operational simplicity, high robustness, efficiency and turnover frequency, the utilization of aqueous media and simple product work-up make this protocol a great option for stilbene syntheses by Mizoroki–Heck reaction.

Synthesis of [2,2’]Bifuranyl‐5,5’‐dicarboxylic Acid Esters via Reductive Homocoupling of 5‐Bromofuran‐2‐carboxylates Using Alcohols as Reductants†

“…PVP was found to be the optimal, giving 1b in 74% yield. It is worth noting that although PVP‐stabilized Pd is widely used to catalyze organic transformations such as Heck [ 54‐60 ] and Suzuki coupling reactions, [ 61‐64 ] it has not, to our knowledge, been used for reductive homocoupling reactions yet. With PVP as the stabilizer, PdCl 2 , Pd(PPh 3 ) 4 , Pd(MeCN) 2 Cl 2 , PdBr 2 , and Pd(OAc) 2 gave lower yields than Pd(PPh 3 ) 2 Cl 2 (entries 6—10).…”

Recent Advances in Microwave‐assisted Cross‐Coupling Reactions

“…In the year 2017, Martín group [82] electrochemically prepared PVP−Pd NPs catalyst through the colloidal Pd nano‐catalyst immobilized on poly( N ‐vinylpyrrolidone) (PVP). They used this PVP−Pd NPs catalyst in the Mizoroki–Heck reaction to synthesize stilbenes 139 from the reaction between aryl/heteroaryl bromides or iodides 13 with various olefins 138 in H 2 O under MW irradiation (Scheme 62).…”

Palladium nanoparticles for the synthesis of phenanthridinones and benzo[c]chromenes via C–H activation reaction

“…Our ongoing research on the development of Pdnanocatalysts for organic transformations, [69][70][71][72][73] prompted us to explore the synthesis of phenanthridine-6(5H)-ones and benzo [c]chromenes using Pd-PVP NPs. Thus, herein, the reactivity of these NPs in the Pd-catalyzed C-H bond activation for the intramolecular arylation reaction of benzamides and aryl benzyl ethers is reported.…”