Polyvinylpolypyrrolidone-Supported Boron Trifluoride; Highly Efficient Catalyst for the Synthesis of N-tert-Butyl Amides (original) (raw)
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Monatshefte für Chemie/Chemical Monthly, 2009
Highly efficient method for the preparation of N-tert-butyl amides by reaction of nitriles with tert-butyl acetate is described using polyvinylpolypyrrolidone-supported boron trifluoride (PVPP-BF 3) at 70 °C in good to excellent yields. Selective amidation of benzonitrile in the presence of acetonitrile was also achieved. polyvinylpolypyrrolidone-boron trifluoride complex shows non-corrosive and stable solid catalyst elevated Lewis acid property.
Chemistry – A European Journal, 2019
The Lewis acidic character of borinic‐acid‐functionalized polymers suggests broad potential applications in supramolecular materials, chemo‐ and biosensors, as well as supported catalysts. Two highly electron‐deficient borinic acid copolymers (3 a and 3 b) with variable steric hindrance at the boron center were prepared by reaction of aryldibromoboranes ArBBr2 (2, Ar=2,4‐Cl2Ph, 3,5‐Cl2Ph) with a 10 % stannylated polystyrene random copolymer, followed by conversion to the desired PS‐B(Ar)OH functionalities. The supramolecular assembly of these polymers through Lewis acid–Lewis base interactions and reversible covalent B−O−B bond formation was investigated. Exposure of a polymer solution of 3 a to pyridine triggered spontaneous gelation, whereas 3 b only gelled upon addition of molecular sieves to favor formation of boroxane crosslinks. The crosslinking process was readily reversed by addition of small amounts of water or wet solvent. The dynamic processes were studied in detail by va...
Mechanistic insights into boron-catalysed direct amidation reactions
Chemical science, 2018
The generally accepted monoacyloxyboron mechanism of boron-catalysed direct amidation is brought into question in this study, and new alternatives are proposed. We have carried out a detailed investigation of boron-catalysed amidation reactions, through study of the interaction between amines/carboxylic acids and borinic acids, boronic acids and boric acid, and have isolated and characterised by NMR/X-ray crystallography many of the likely intermediates present in catalytic amidation reactions. Rapid reaction between amines and boron compounds was observed in all cases, and it is proposed that such boron-nitrogen interactions are highly likely to take place in catalytic amidation reactions. These studies also clearly show that borinic acids are not competent catalysts for amidation, as they either form unreactive amino-carboxylate complexes, or undergo protodeboronation to give boronic acids. It therefore seems that at least three free coordination sites on the boron atom are necess...
ChemInform, 2015
Tris(pentafluorophenyl)borane catalyzed synthesis of cyanohydrins and trimethylsilylcyanohydrin ethers from carbonyl compounds and α-amino nitriles from imines (Strecker synthesis) has been reported in the presence of trimethylsilylcyanide. The substrate diversity has been extensively studied; various aldehydes, ketones and imines are participating in the methodology. Simple and mild reaction conditions, low levels of catalyst loading and shorter reaction times and high yields are the highlights of this methodology, also the products formed here are very important building blocks in the several biologically active natural products.