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Deuterated organic molecules provide the basis for many applications in life sciences and material research. Thus, methodologies to access labeled compounds with defined selectivity continue to be important. Using KOtBu as base and DMSO‐d6 as deuterium source, we present a general and applicable method for the selective deuteration of a set of nitrogen‐containing heterocycles (pyridines, azines and bioactive molecules). Experimental and DFT mechanistic studies indicate that this reaction proceeds via deprotonation of the substrates by the dimsyl anion. The relative thermodynamic stability of the heterocycle anions determines the distribution and degree of deuteration. [ABSTRACT FROM AUTHOR]

A novel one‐pot iridium‐catalyzed domino hydroxymethylation of olefins, which relies on using two different ligands at the same time, is reported. DFT computation reveals different activities for the individual hydroformylation and hydrogenation steps in the presence of mono‐ and bidentate ligands. Whereas bidentate ligands have higher hydrogenation activity, monodentate ligands show higher hydroformylation activity. Accordingly, a catalyst system is introduced that uses dual ligands in the whole domino process. Control experiments show that the overall selectivity is kinetically controlled. Both computation and experiment explain the function of the two optimized ligands during the domino process. [ABSTRACT FROM AUTHOR]

Acceptorless dehydrogenation of 1‐phenylethanol to acetophenone catalyzed by OH‐functionalized N‐heterocyclic carbene Cp*Ir(NHC) complexes under base‐free condition as well as under the promotion of protic co‐solvent tBuOH were investigated using density functional theory including solvation and van der Waals dispersion corrections. The first step is the 1‐phenylethanol dehydrogenation, which is more favored via an inner‐sphere over an outer‐sphere mechanism. The second step is H2 formation from Ir–H and O–H functionalities, which is the rate‐determining step, in agreement with the observed kinetic isotopic effect. The protic co‐solvent and 1‐phenylethanol act as a shuttle for proton transfer for the formation of H2. [ABSTRACT FROM AUTHOR]

Density functional theory computations have been carried out to investigate the base free acceptor‐less dehydrogenative coupling of benzyl alcohol to benzyl benzoate catalyzed by defined Mn and Re PNP pincer amido M(CO)2(PNP) and amino HM(CO)2(PNHP) complexes [M = Mn, Re; PNP = N{CH2CH2P(isopropyl)2}2]. Benchmark calculations show that B3PW91 have the best and closest agreement with the experiments than DLPNO‐CCSD(T). Within all proposed elementary steps, the non‐innocent outer‐sphere mechanism incorporating the amido complex and the N–H bond is more kinetically favored than the innocent outer‐sphere mechanism without the amido complex as well as the inner‐sphere mechanism via the de‐coordination of one phosphine ligand to create a vacant site for β‐hydride elimination. The dehydrogenation of hemiacetal to ester represents the rate‐determining step. Both Mn and Re‐based catalysts have close free energy barriers and similar catalytic activity. However, the computed apparent barrier is overestimated on the basis of the experimentally determined TOF for the Mn‐based complexes. DFT calculations help elucidate the mechanism of the base free acceptorless dehydrogenative coupling of benzyl alcohol to benzyl benzoate catalyzed by Mn and Re PNP pincer amido and amino complexes. It was determined that the non‐innocent outer‐sphere mechanism is more favorable than the innocent outer‐sphere and inner‐sphere mechanisms, and the dehydrogenation of hemiacetal to ester represents the rate‐determining step. [ABSTRACT FROM AUTHOR]

The chemoselective dehydrogenative silylation and hydrogenation of 1,3‐divinyldisiloxane by using HSiMe3 catalyzed by CpFe(CO)2Me (Cp = η5‐cyclopentadienyl) was explored by DFT computations. The active catalyst, CpFe(CO)SiMe3, was generated from a CO‐assisted pathway and HSiMe3‐initiated acetaldehyde reductive elimination. Starting from the active catalyst, the dehydrogenative silylation step of the first vinyl group was found to be the rate‐determining step, and the subsequent chemoselective hydrogenation step of the second vinyl group was discovered to be kinetically more favored. Within the reaction, the oxygen atom of 1,3‐divinyldisiloxane was not found to play a role in competitive coordination. The computed results rationalize the experimentally observed chemoselectivity. [ABSTRACT FROM AUTHOR]

Abstract: [Fe(PNP)(CO)HCl] (PNP=di‐(2‐diisopropylphosphanyl‐ethyl)amine), activated in situ with KOtBu, is a highly active catalyst for the isomerization of allylic alcohols to ketones without an external hydrogen supply. High reaction rates were obtained at 80 °C, but the catalyst is also sufficiently active at room temperature with most substrates. The reaction follows a self‐hydrogen‐borrowing mechanism, as verified by DFT calculations. An alternative isomerization through alkene insertion and β‐hydride elimination could be excluded on the basis of a much higher barrier. In alcoholic solvents, the ketone product is further reduced to the saturated alcohol. [ABSTRACT FROM AUTHOR]

Abstract: Commercially available Ru‐MACHOTM‐BH is an active catalyst for the hydrogenation of several functional groups and for the dehydrogenation of alcohols. Herein, we report on the new application of this catalyst to the base‐free transfer hydrogenation of carbonyl compounds. Ru‐MACHOTM‐BH proved to be highly active and selective in this transformation, even with α,β‐unsaturated carbonyl compounds as substrates. The corresponding aliphatic, aromatic and allylic alcohols were obtained in excellent yields with catalyst loadings as low as 0.1–0.5 mol % at mild temperatures after very short reaction times. This protocol tolerates iPrOH and EtOH as hydrogen sources. Additionally, scale up to multi‐gram amounts was performed without any loss of activity or selectivity. An outer‐sphere mechanism has been proposed and the computed kinetics and thermodynamics of crotonaldehyde and 1‐phenyl‐but‐2‐en‐one are in perfect agreement with the experiment. [ABSTRACT FROM AUTHOR]

A mixed decamethyltitanocene(III) isonitrile alkynyl complex ( 7) was synthesized by the sequential introduction of the isonitrile and alkynyl ligands. Direct synthesis results in the formation of the diamagnetic decamethyltitanocene bis(isonitrile) ( 2) and bis(alkynyl) ( 3) complexes. Compound 7 undergoes disproportionation at room temperature to give 2 and 3. All complexes were fully characterized by IR, NMR, and EPR spectroscopy, and mass spectrometry. Molecular structures for complexes 2 and 7 are reported. The stability and reactivity of these complexes are rationalized by DFT computations. [ABSTRACT FROM AUTHOR]

Keywords: Density functional calculations; Deuterium; Heterocycles; Hydrogen isotope exchange; Isotopic labeling EN Density functional calculations Deuterium Heterocycles Hydrogen isotope exchange Isotopic labeling 1 1 1 05/23/22 20220519 NES 220519 B The Front Cover b illustrates how the thermodynamic stability of intermediary anions governs selectivity in the remote base-mediated deuteration of pyridine derivatives. Density functional calculations, Deuterium, Heterocycles, Hydrogen isotope exchange, Isotopic labeling The strongest weightlifters - i. e. the most stable anions - can lead to the best deuterium incorporation, which is why the C4 anion of our model substrate wins the competition and can lift the 4-deuterated pyridine. [Extracted from the article]

An efficient procedure for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, with molecular oxygen under ambient conditions has been achieved. By applying catalytic amounts of Pd(OAc)2 in the presence of tertiary phosphine oxides (OPR3) as ligands, a variety of substrates are selectively oxidized without formation of ester byproducts. Spectroscopic investigations and DFT calculations suggest stabilization of the active palladium(II) catalyst by phosphine oxide ligands. [ABSTRACT FROM AUTHOR]

A detailed mechanism of hydrogen production by reduction of water with decamethyltitanocene triflate [Cp*2TiIII(OTf)] has been derived for the first time, based on a comprehensive in situ spectroscopic study including EPR and ATR-FTIR spectroscopy supported by DFT calculations. It is demonstrated that two H2O molecules coordinate to [Cp*2TiIII(OTf)] subsequently forming [Cp2*TiIII(H2O)(OTf)] and [Cp*TiIII(H2O)2(OTf)]. Triflate stabilizes the water ligands by hydrogen bonding. Liberation of hydrogen proceeds only from the diaqua complex [Cp*TiIII(H2O)2(OTf)] and involves, most probably, abstraction and recombination of two H atoms from two molecules of [Cp*TiIII(H2O)2(OTf)] in close vicinity, which is driven by the formation of a strong covalent TiOH bond in the resulting final product [Cp*2TiIV(OTf)(OH)]. [ABSTRACT FROM AUTHOR]

A general and efficient method for the palladium-catalyzed carbonylative coupling of aryl iodides to benzyl acetylenes has been developed. Various furanones have been prepared in excellent yields from their corresponding benzyl acetylenes at room temperature under a CO atmosphere. For aliphatic alkynes, their corresponding alkynones were obtained in good yields. Detailed DFT calculations have also been carried out to understand the reaction pathway and the most probable reaction mechanism has been proposed. [ABSTRACT FROM AUTHOR]

Abstract: Density functional theory computations have been carried out on the adsorption of NO, NO2, pyridine and pyrrole on the α-Mo2C(0001) surface for understanding the hydrodenitrogenation processes. On the Mo-terminated surface, NO decomposes into surface N and O, and NO2 dissociates into surface O and NO without any barriers, while the most stable adsorption modes of pyridine and pyrrole have π-face coordination over the three-fold molybdenum hollow sites with strongly destroyed aromatic systems. On the C-terminated surface, adsorbed surface species have been found for NO and NO2, while destroyed ring systems are found for pyridine and pyrrole. It is found that adsorption on the Mo-terminated surface is much stronger than that on the C-terminated surface. [Copyright &y& Elsevier]