Thiadiazolidine 1-oxide systems for phosphine-free palladium-mediated catalysis

Abstract

NMP, NaOAc, TBAB

A PdCl2–ionic liquid brush assembly: an efficient and reusable catalyst for Mizoroki–Heck reaction in neat water

“…Electronic effects have a great effect on the yield of coupling product. Although electron-withdrawing and electron-donating substituents on the aryl halide did not have a detrimental effect on the ability of the catalyst to promote this reaction to completion, aryl halides with electron-withdrawing groups gave higher yields than those with electron-donating substituents, which is similar to the M-H reaction reported previously (entries 10-12, 13 vs. [14][15][16][17][18]. This could also be confirmed by the observation that although it was difficult for bromobenzene to give a coupling product, a considerable improvement in yield in the case of 4-bromonitrobenzene was obtained due to the presence of strong electron-withdrawing substituent NO 2 on the phenyl ring (entry 20).…”

“…Therefore, in order to obtain a higher yield, the reaction time should not be less than 24 h. In view of the fact that the yield of cinnamic acid increased slightly from 24 h to 48 h (entries 4,9), the reaction mixture usually refluxed for 24 h in subsequent experiments. To verify the effectiveness and generality of this procedure, the reactions of various aryl halides with acrylic acid were examined under the optimized reaction conditions ( Table 1, entries [10][11][12][13][14][15][16][17][18][19][20][21][22]. All of the present reactions were carried out in neat water without the need for phase transfer catalyst and protection from air, showing that the methodology has distinct advantages.…”

“…[4] Many palladium catalysts with excellent catalytic activities have been developed, such as phosphine ligand catalysts, [5][6][7] palladacycle catalysts, [8][9][10][11] N-heterocyclic carbene (NHC) ligand catalysts [12][13][14] and phosphine-free catalysts. [15,16] However, in both homogeneous or heterogeneous catalytic systems, in order to overcome the incompatibility of lipophilic substrates and inorganic base, these M-H reactions are often conducted in polar aprotic solvents, such as DMF, [17][18][19][20] N,N-dimethylacetamide (DMA) [21][22][23][24] and N-methylpyrrolidone (NMP). [25][26][27][28] Organic solvents not only enhance the reaction rate but also bring about environmental pollution because many polar solvents are toxic.…”

Organometallic chemistry

“…By varying the ligand structure and probing reaction conditions, catalyst loading as low as 0.00002 mol% were obtained and pre-prepared ligand-palladium conjugates were found to be easy to handle bench stable materials. 5 Roger et al showed that a wide range of aryl bromides could be employed in direct arylation of heteroaromatic species bearing unprotected alcohols. Scheme 2 shows the phosphine-free conditions employed in the direct arylation of thiophenecontaining substrates, providing ready access to a useful range of coupled products bearing formyl, ester, trifluoromethyl, fluoro, acetyl, nitro and nitrile functionality on the aromatic (Ar) fragment.…”

Three-Component Asymmetric Polymerization toward Chiral Polymer

“…4 di-secondary amines including AM2, AM3, AM4, and AM6 were synthesized and fully characterized except the commercially available monomers. [36][37][38] (Scheme…”