The role of F-N reagent and reaction conditions on fluoro functionalisation of substituted phenols

The effect of steric interactions on the regioselectivity of fluorination of para alkyl substituted phenols was investigated and the strong effect of size of the alkyl substituent, the structure of the F-N reagent and the solvent on the site of fluorination was established. The course of reaction obeyed a second order rate equation, while the fluorination process required higher ΔH^≠ activation than oxidation or oxidative demethylation. Solvent polarity variations had a small effect on the rate of functionalisation, while an excellent Hammett correlation with ρ⁺=−2.3 was determined.     

Basic CuCO3/ligand as a new catalyst for 'on water' borylation of Michael acceptors,alkenes and alkynes: application to the efficient asymmetric synthesis of β‐alcohol type sitagliptin side chain

The efficient 'on water' β‐borylation using bis(pinacolato)diboron agent was achieved with a newly developed catalytic system based on basic copper carbonate and various ligands. The catalytic system was used for β‐borylation of various Michael acceptors, alkenes and alkynes. The presented methodology was successfully applied to the novel synthesis of β‐alcohol type sitagliptin side chain precursor via water‐based highly enantioselective β‐borylation followed by an oxidation process. Copyright © 2013 John Wiley & Sons, Ltd.     

Effective and selective iodofunctionalisation of organic molecules in water using the iodine-hydrogen peroxide tandem

Efficient hydrogen peroxide enhanced iodofunctionalisation of ketones, 1,3-dicarbonyl derivatives and activated aromatic molecules using elemental iodine in water is achieved, whereas alkynes were stereoselectively converted into (E)-1,2-diiodoalkenes.     

Use of a fluorous bridge for diffusion controlled uptake of molecular chlorine in chlorine addition to alkenes

Fluorous solvent was used for passive transport of molecular chlorine from one side of the U-tube to the other, where addition of chlorine to alkenes was quantitative and diffusion controlled.     

Halogenation of ketones with N-halosuccinimides under solvent-free reaction conditions

Several aryl substituted ketones, cyclic ketones, 1,3-diketones and a β-ketoamide were halogenated with N-halosuccinimides under solvent-free reaction conditions (SFRC) at various temperatures (20-80 °C), whereas less enolized ketones required the presence of an acid catalyst (p-toluenesulfonic acid, PTSA). Bromination of substituted acetophenones obeys first order kinetics v=k_Br[ketone] and the following correlation with the keto-enol equilibrium constant: log k_Br=0.3pK_E+C₁, less enolized substrates being more reactive; the moderate positive charge developed in the rate determining step was confirmed by the Hammett correlation (ρ=−0.5). On the other hand, in cyclic ketones an opposite relation was observed: log k_Br=−0.6pK_E+C₂, indicating higher reactivity of substrates with higher enolization constant (K_E). The important role of the nature of the solvent (MeCN, MeOH) in preorganization of the ketone-NBS-PTSA mixture prior to SFRC bromination was found.     

The role of multifunctionalized amine structure and reaction conditions on the transformations of crosslinked copoly(styrene-p-nitrophenylacrylate)

Crosslinked copoly(styrene-p-nitrophenylacrylates), containing 2% (1) or 4% DVB (2) were converted with various diaminoalkanes (1,2-diaminoethane 3a, 1,4-diaminobutane 3b, 1,8-diaminooctane 3c) to amides. The degree of additional crosslinking depended on the chain length of the diaminoalkane, the molar ratio of ester function in 1 or 2 to diaminoalkane, solvent polarity (dimethylformamide, chloroform, toluene), while reaction temperature (50 or 100°C) had only a minor effect. 2 was also converted with various amines bearing additional functional groups (ethanolamine, 3-amino-1-propanol, 4-aminomethylpyridine, 2-(2-aminoethylamino)-ethanol, 2-(2-aminoethoxy)-ethanol, 6-aminocaproic acid, N-propylaminomorpholine, 3-N,N-diethylamino-1-propylamine) to the corresponding amides. The swelling ability of the resins depended on the crosslinking of the starting copoly(styrene-p-nitrophenylacrylate) (1, 2), the structure of the amide, the degree of additional crosslinking, and solvent polarity (chloroform, dimethylformamide, methanol, toluene). The accessibility of nitrogen atoms in the polymer matrix was examined by EtX functionalization of the 3-N,N-diethylamino-1-propylamine derivative (10) and 4-aminomethylpyridine derivative (13), and more than 85% functionalization was found. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1699–1706, 1998     

Halogenation of organic compounds in ionic liquids

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The review summarizes, compares and analyzes the data available on halogenation reactions in ionic liquid media.