The effect of fluorination on the conformational and hydrogen‐bond (HB)‐donating properties of a series of benzyl alcohols has been investigated experimentally by IR spectroscopy and theoretically ...with quantum chemical methods (ab initio (MP2) and DFT (MPWB1K)). It was found that o‐fluorination generally resulted in an increase in the HB acidity of the hydroxyl group, whereas a decrease was observed upon o,o′‐difluorination. Computational analysis showed that the conformational landscapes of the title compounds are strongly influenced by the presence of o‐fluorine atoms. Intramolecular interaction descriptors based on AIM, NCI and NBO analyses reveal that, in addition to an intramolecular OH⋅⋅⋅F interaction, secondary CH⋅⋅⋅F and/or CH⋅⋅⋅O interactions also occur, contributing to the stabilisation of the various conformations, and influencing the overall HB properties of the alcohol group. The benzyl alcohol HB‐donating capacity trends are properly described by an electrostatic potential based descriptor calculated at the MPWB1K/6‐31+G(d,p) level of theory, provided solvation effects are taken into account for these flexible HB donors.
Fluorination and hydrogen‐bond acidity: Fluorination of benzyl alcohols is shown to significantly modify their hydrogen‐bonding properties and their conformational landscapes through intramolecular OH⋅⋅⋅F, CH⋅⋅⋅F and/or CH⋅⋅⋅O interactions (see scheme). ortho‐Fluorination results in an increase in the hydrogen‐bond acidity of the hydroxyl group, whereas o,o′‐difluorination leads to a decrease in the hydrogen‐bond acidity.
The bis(acetonitrile)palladium(II) chloride complex, PdCl2(MeCN)2, efficiently catalyzes the regioselective alkylation of indoles with various benzylic and allylic alcohols under moisture and air ...insensitive conditions. Notably the reaction does not require any other co‐catalyst, acid, base, additive, or external ligand.
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•The position of the immobilised Ag(I) ions was comprehensibly characterized in the AgBi-hybrid material (AgBi-HM).•The stability of the AgBi-HM catalyst was tested in various ...solvents under demanding flow conditions.•AgBi-HM was reactive and extremely selective in the dehydrogenation of a wide scope benzylic alcohols.
In the present contribution, we are reporting our findings on the structure, stability and synthetic applicability of a silver-containing hybrid material, which has recently been introduced by our research groups as a mineralogically-inspired novel heterogeneous catalyst. To determine how silver ions can be fixed into the structure of the catalyst, a set of experiments was designed with modification of the interlayer gallery under hydrothermal conditions. Subsequently, the stability of the material was examined in various solvents under demanding continuous flow conditions with the aim of achieving a clear picture of its applicability in organic syntheses. On the basis of the useful data obtained during the stability tests, a continuous flow methodology was developed for catalytic dehydrogenation of diversely substituted benzylic alcohols. As far as selectivity is concerned the catalyst performed superbly, while the conversions were varied from fair to extremely good.
We discovered an efficient protocol for the conversion of tertiary and secondary benzylic alcohols into the corresponding alkanes in good to quantitative yields by employing tin(IV) ion-exchanged ...montmorillonite (Sn-Mont) as a solid acid catalyst and Et3SiH as the hydride source. The reaction is likely to proceed via the SN1-type reaction mechanism, that is, the formation of carbenium ions, followed by the addition of a hydride from the silane. The work-up of the reaction only requires simple filtration of the solid acid without any neutralization of the acid catalyst.
An efficient and practical method for the construction of 2-aryl- and 2-alkyl-substituted benzothiazoles via a copper-catalyzed redox condensation process between benzothiazoles and aldehydes or ...benzylic alcohols has been developed. The reaction proceeded under mild reaction conditions using environmentally benign tert-butyl hydroperoxide (TBHP) as the oxidant. A reaction mechanism involving the ring-opening of benzothiazoles initiated by the attack of acyl radical on the thiazole ring and intramolecular condensation is proposed based on the isolation of an anilide disulfide intermediate.
Reported herein is the identification of a new methodology for the dibromination of benzylic diols. This method proceeds in moderate to good yields for a wide variety of electron-deficient, ...electron-neutral, and electron-rich aromatic substrates. Moreover, the reagent, 1,3-dibromo-5,5-dimethylhydantoin, and the solvent, tetrahydrofuran, are substantially more environmentally benign than traditional solvents and reagents used for bromination. The utility of this methodology was demonstrated in the high-yielding synthesis of a key intermediate in the synthesis of omeprazole.
The catalytic activity of copper-manganese (CuMn2) mixed oxide nanoparticles (Cu/Mn=1:2) has been studied for the selective oxidation of benzylic alcohols to the corresponding aldehydes using ...molecular oxygen as an oxidizing agent. The CuMn2 mixed oxide showed excellent catalytic activity for the oxidation of benzylic alcohols to the corresponding aldehydes with high selectivity (>99%). The complete conversion (100%) of all the benzylic alcohols to the corresponding aldehydes is achieved within a short reaction period at 102°C. The catalytic performance is obtained to be dependent on the electronic and steric effects of the substituents present on the phenyl ring. Electron withdrawing and bulky groups attached to the phenyl ring required longer reaction time for a complete conversion of the benzylic alcohols.
A convenient and efficient method for the synthesis of polysubstituted indenes has been developed by the iron(III) trichloride‐catalyzed tandem mono‐ and dibenzylation/cyclization reactions of ...benzylic alcohols with alkynes. This method is featured with the easily available starting materials, cheap catalyst, simple manipulation and mild conditions.
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