Joint ITC and DFT Study of the Affinity of Some Lewis Bases to HIFP in Solution

HFIP, i.e. 1,1,1,3,3,3-hexafluoropropan-2-ol, was found to be an exceptional medium,[1] either as solvent or co-solvent, that allows many reactions to occur.[2-5] However, the exact role and mode of action of HFIP in various chemical transformations still remains elusive. Despite many reports dealing with water/HFIP complexes, little has been published on other molecular complexes of HFIP as well as on thermochemistry of the formation of such complexes.[6] Within this study the affinity of a series of eight different Lewis bases (3 sulfoxides, 3 Nsp2 pyridine derivatives, 1 aromatic amine, 1 cyclic aliphatic ether) to HFIP (as Lewis acid) is investigated experimentally by Isothermal Titration Calorimetry (ITC) and theoretically using static DFT-D calculations. Measured ITC association enthalpy values ΔHaITC spanned -9.3 kcal/mol - -14 kcal/mol. Computations including a PCM implicit solvation model produced similar exothermicity of association of all studied systems - ΔHa values ranging -8.5 – -12.7 kcal/mol. In general, most of interaction energy is due to the hydrogen bonding and not due to formation of significantly strong halogen bonds. An additional set of calculations combining implicit and explicit solvation by chlorobenzene of the reactants, pointed out the relatively low interference of the solvent with the HFIPbase complexation, which main effect is to slightly enhance the Gibbs energy of the HFIP-Lewis base association. It is speculated that the interactions of bulk HFIP with Lewis bases therefore may significantly intervene in catalytic processes not only via the dynamic miscrostructuration of the medium but also more explicitly by affecting bonds’ polarization at the Lewis bases

Supplementary data for the article: Milovanović, M. R.; Dherbassy, Q.; Wencel‐Delord, J.; Colobert, F.; Zarić, S. D.; Đukić, J.-P. The Affinity of Some Lewis Bases for Hexafluoroisopropanol as a Reference Lewis Acid: An ITC/DFT Study. ChemPhysChem 2020, 21 (18), 2136–2142. https://doi.org/10.1002/cphc.202000560.

Supplementary material for: [https://doi.org/10.1002/cphc.202000560]Related to published version: [https://cherry.chem.bg.ac.rs/handle/123456789/4337]Related to accepted version: [https://cherry.chem.bg.ac.rs/handle/123456789/4339

Late stage C―H activation of a privileged scaffold; synthesis of a library of benzodiazepines

A library of over twenty 5-(2-arylphenyl)-1,3-dihydro-2H-1,4-benzodiazepin-2-ones has been formed by a microwave-mediated late-stage palladium-catalysed arylation of 1,4-benzodiazepines using diaryliodonium salts. This can also be applied to nordazepam (7-chloro-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one), the active metabolite of diazepam, and subsequent N-alkylation and/or H/D exchange allows further diversification towards elaborated pharmaceuticals and their 3,3'-deuterated analogues

Increasing Catalyst Efficiency in C−H Activation Catalysis

C−H activation reactions with high catalyst turnover numbers are still very rare in the literature and 10 mol % is a common catalyst loading in this field. We offer a representative overview of efficient C−H activation catalysis to highlight this neglected aspect of catalysis development and inspire future effort towards more efficient C−H activation. Examples ranging from palladium catalysis, Cp*Rh III - and Cp*Co III -catalysis, the C−H borylation and silylation to methane C−H activation are presented. In these reactions, up to tens of thousands of catalyst turnovers have been observed

Cp*Co(III)-Catalyzed coupling of benzamides with α,β-unsaturated carbonyl compounds: Preparation of aliphatic ketones and azepinones

A Cp*Co(III)-catalyzed C-H functionalization of benzamide substrates with α,β-unsaturated ketones has been optimized, providing a facile route towards aliphatic ketone products. When employing α,β-unsaturated aldehydes as coupling partners, under the optimized protocol, a cascade reaction forming azepinones has also been developed. Finally, DFT studies have demonstrated how stabilization of a metallo-enol intermediate when employing α,β-unsaturated ketones is the driving force leading to the observed aliphatic ketone product rather than olefinic products reported using α,β-unsaturated esters as coupling partners

Iridium(I)-Catalyzed Intramolecular Hydrocarbonation of Alkenes: Efficient Access to Cyclic Systems Bearing Quaternary Stereocenters

This is the peer reviewed version of the following article: David Fernández, Moisés Gulías, José L. Mascareñas, Fernando López (2017), Iridium (I)-Catalyzed Intramolecular Hydrocarbonation of Alkenes: Efficient Access to Cyclic Systems Bearing Quaternary Stereocenters, Angew. Chem. Int. Ed., 56, 9541-9545 [doi: 10.1002/anie.201705105]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for self-archivingA catalytic, versatile and atom-economical C−H functionalization process that provides a wide variety of cyclic systems featuring methyl-substituted quaternary stereocenters is described. The method relies on the use of a cationic IrI–bisphosphine catalyst, which promotes a carboxamide-assisted activation of an olefinic C(sp2)−H bond followed by exo-cyclization to a tethered 1,1-disubstituted alkene. The extension of the method to aromatic and heteroaromatic C−H bonds, as well as developments on an enantioselective variant, are also describedThis work has received financial support from the spanish MINECO grants (SAF2016-76689-R, CTQ2016-77047-P), Xunta de Galicia (GRC2013-041, 2015-CP082 and Centro Singular de Investigación de Galicia accreditation 2016–2019 ED431G/09), the European Union (European Regional Development Fund – ERDF) and ERC (Adv. Grant No. 340055). D.F.F. thanks the MINECO for a fellowship. The Orfeo-Cinqa network CTQ2014-51912-REDC is kindly acknowledgedS

Combining C-H functionalisation and flow photochemical heterocyclic metamorphosis (FP-HM) for the synthesis of benzo[1,3]oxazepines

C-H Activation/functionalisation and Flow Photochemical Heterocyclic Metamorphosis (FP-HM) have been combined to synthesize a library of benzo[1,3]oxazepines, a rarely described heterocyclic family. This combined protocol allows a range of arylated products to be made from simple starting materials, and the cheap flow photochemical system has proven effective for rapid synthesis of gram-quantities of benzo[1,3]oxazepines

Synthesis of spirocyclic enones by rhodium-catalyzed dearomatizing oxidative annulation of 2-alkenylphenols with alkynes and enynes

The dearomatizing oxidative annulation of 2-alkenylphenols with alkynes and enynes proceeds with high yields and regioselectivities under Rh(III) catalysis. These reactions are successful using Cu(OAc)2 or air as the stoichiometric oxidant, and provide spirocyclic enones, the basic ring system of which appears in several natural products. Application of this process to the preparation of a highly functionalized tetracycle is also demonstrated