Abstract We present evidence that the privileged use of 3,5‐bis(trifluoromethyl)phenyl group in thiourea organocatalysis is due to involvement ortho ‐CH bond binding event with Lewis‐basic sites. utilized a combination low‐temperature IR spectroscopy, 2D NMR nano‐MS (ESI) investigations, as well density functional theory computations [M06/6‐31+G( d , p ), including solvent corrections natural orbital and atoms‐in‐molecules analyses] support our conclusions bear implications for catalyst design.

The metal-induced coupling of tertiary diamondoid bromides gave highly sterically congested hydrocarbon (hetero)dimers with exceptionally long central C–C bonds up to 1.71 Å in 2-(1-diamantyl)[121]tetramantane. Yet, these dimers are thermally very stable even at temperatures above 200 °C, which is not line common bond length versus strengths correlations. We suggest that the extraordinary stabilization arises from numerous intramolecular van der Waals attractions between neighboring...

We report a new thiourea–Brønsted acid cooperative catalytic system for the enantioselective cyanosilylation of aldehydes with yields up to 90% and enantioselectivities 88%. The addition an achiral was found be crucial high asymmetric induction. Mechanistic investigations using combination NMR, ESI-MS, density functional theory computations (including solvent corrections) at M06/6-31G(d,p) level suggest that key species results from interaction bifunctional thioureas form well-defined chiral...

The storage of energy in a safe and environmentally benign way is one the main challenges today's society. Ammonia-borane (AB=NH3 BH3 ) has been proposed as possible candidate for chemical hydrogen. However, efficient release hydrogen still an active field research. Herein, we present metal-free bis(borane) Lewis acid catalyst that promotes evolution up to 2.5 equivalents H2 per AB molecule. can be reused multiple times without loss activity. moderate temperature 60 °C allows controlling...

The selective functionalizations of the fundamental hydrogen-terminated nanodiamonds triamantane 1, as well most symmetrical representative tetramantanes (C2h-[121]tetramantane 2) were elaborated. Electrophilic reagents (Br2, HNO3) predominantly attack medial C−H positions cages; bromination 2 gave 2-bromo derivative almost exclusively. Highly apical substitution in 1 and is possible either under single-electron-transfer oxidations via hydrocarbon radical cations or through photoacetylation...

We have studied the formation of several N-acetyl-4-(dimethylamino)pyridine (DMAP) salts (with Cl(-), CH(3)COO(-), and CF(3)COO(-) counterions), which are considered to be catalytically active species in DMAP-catalyzed acetylation reactions alcohols. Combined crystal structure analyses, variable temperature matrix IR NMR spectroscopy as well computational techniques at UAHF-PCM-B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level were utilized examine structures dynamics salt formation. found clear...

A new transition-metal-free mode for the catalytic reduction of carbon dioxide via bidentate interaction has been developed. In presence Li2[1,2-C6H4(BH3)2], CO2 can be selectively transformed to either methane or methanol, depending on reducing agent. The nature binding is supported by X-ray analysis an intermediate analogue, which experiences special stabilization due aromatic character in interaction. Kinetic studies revealed a first-order reaction rate. transformation conducted without...

We present an experimental and computational study on the conformers of N,N'-diphenylthiourea substituted with different dispersion energy donor (DED) groups. While unfolded anti-anti conformer is most relevant for thiourea catalysis, intramolecular noncovalent interactions counterintuitively favor folded syn-syn conformer, as evident from a combination low-temperature nuclear magnetic resonance measurements computations. In order to quantify interactions, we utilized local decomposition...

The influence of acid leaching on a commercial zeolite beta with concentrated solutions HCl and HNO3 has been investigated. parent modified zeolites are characterized ICP, BET, XRD, SEM, FTIR, 27Al solid-state NMR, conventional MAS, CP/MAS two-dimensional multiple-quantum MAS (MQMAS) techniques. first advantage to submitting an procedure is remove or passivate all kinds extra-framework impurities from aluminium clusters silica–alumina debris. These have shown be some extent acidic. However,...

To model the chemical properties of hydrogen-terminated nanodiamond {111} and {110} surfaces, functionalizations higher diamondoid [1(2,3)4]pentamantane were studied. [1(2,3)4]Pentamantane reacts selectively with neat bromine to give medial 2-mono- 2,4-disubstitution products. In contrast, oxidation nitric acid as well single-electron-transfer involving radical cation results in apical C7-substitutions. This substitution pattern dominates free-radical bromination under phase-transfer...

We present an experimental and computational study of a cyclooctatetraene (COT)-based molecular balance disubstituted with commonly used silyl groups. Such groups often serve as protecting are typically considered innocent bystanders. Our motivation here is to determine the actual steric effects such by employing balance. While in unfolded 1,4-valence isomer far apart (dσ–σ ≥ 5.15 Å), folded 1,6-isomer affected greatly noncovalent interactions due close σ–σ contacts ≤ 2.58 Å). In order...

Abstract The fusion of the sp 3 ‐hybridized parent diamondoid adamantane with 2 pyrene results in a hybrid structure very large dipole moment which arises from bending moiety. Presented herein is synthesis, study electronic and optical properties, as well dynamic behavior this new hydrocarbon.

This letter presents the side-chain iodination of electron-deficient benzylic hydrocarbons at rt using N-hydroxyphthalimide (NHPI) as radical initiator and 1,3-diiodo-5,5-dimethylhydantoin 3-iodo-1,5,5-trimethylhydantoin (3-ITMH) iodine source. Addition a carboxylic acid increased reactivity due to complex formation with activation 3-ITMH by proton transfer halogen bond formation. No SEAr reactions were observed under employed reaction conditions. Our method enables convenient product...

We describe an organocatalytic iodination of activated aromatic compounds using 1,3-diiodo-5,5-dimethylhydantoin (DIH) as the iodine source with thiourea catalysts in acetonitrile. The protocol is applicable to a number substrates significantly different steric and electronic properties. generally highly regioselective provides high yields isolated products. NMR kinetic investigations conducted THF-<i>d</i> ₈indicate role sulfur motif nucleophile that assisted by H-bonding key...

Abstract Eine der größten Herausforderungen heutigen Gesellschaft ist die sichere und umweltfreundliche Speicherung von Energie. Amminboran (AB=NH 3 BH ) wurde als mögliche Verbindung für chemische Wasserstoff vorgeschlagen. Die effiziente Freisetzung des Wasserstoffs jedoch immer noch ein aktives Forschungsfeld. Hier präsentieren wir einen metallfreien Dibor‐Lewis‐Säurekatalysator, bis zu 2.5 Äquivalenten H 2 pro AB ermöglicht. Der Katalysator kann dabei mehrfach wiederverwendet werden,...

The mucin MUC1 is a glycoprotein involved in fundamental biological processes, which can be found over-expressed and with distinctly altered glycan pattern on epithelial tumor cells; thus it promising target structure the quest for effective carbohydrate-based cancer vaccines immunotherapeutics. Natural glycopeptide antigens indicate only low immunogenicity T-cell independent immune response; however, this major drawback overcome by coupling of multivalently to immunostimulating carrier...

The monoprotection (desymmetrization) of diamondoid, benzylic, and ethynyl diols has been achieved using fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) under acidic conditions. This practical acid-catalyzed SN1 reaction opens the door for synthesis novel bifunctional diamondoids. With diamantane an example, we show that resulting monoethers can be used to prepare selectively, instance, amino or nitro unnatural acids. These are important compounds in terms exploration electronic,...

Abstract magnified image The selective fluorination of diamantane, triamantane, [121]tetramantane, and [1(2,3)4]pentamantane bromides alcohols was achieved by using the fluorinating agents silver fluoride (AgF) diethylaminosulfur trifluoride (DAST). Various mono‐, di‐, tri‐ even tetrafluorinated diamondoid derivatives were prepared characterized. We also able to prepare amino fluoro alcohol diamantane from corresponding monoprotected diols. These reactions can be carried out in a highly...

Various functional groups have been incorporated into the structures of naturally occurring diamondoids [1(2)3]tetramantane and [12312]hexamantane (cyclohexamantane), which represent hydrogen-terminated prism-shaped nanodiamonds. The selectivities C-H substitutions in depend on reagent employed give products substituted at either central (through bromination) or peripheral nitroxylation photo-oxidation) positions. hydrogen-coupled electron-transfer mechanism with model electrophile...

The zinc complexes [(L1)2Zn(MeOH)2](OTf)2, [(L1)ZnCl2], [(L2)ZnCl2], [(L2)Zn(OTf)(H2O)]OTf and [(Me-bispic)ZnCl2] of the ligands N-[(2-pyridyl)methyl]-2,2′-dipyridylamine (L1), N-[bis(2-pyridyl)methyl]-2-pyridylamine (L2) N-methyl-[bis(2-pyridyl)methyl]amine (Me-bispic) were synthesised characterised. first copper(I) L1 L2 also structurally [(L1)ZnCl2] showed unexpected fluxional behaviour in solution revealed an interesting intramolecular ligand exchange mechanism coordination sphere ion....

Fluoroquinolones are considered as critically important antibiotics. However, they used in appreciable quantities veterinary medicine. Liquid manure and feces can contain substantial amounts of unmetabolized antibiotics and, thus, enter the environment if is for soil fertilization. In this study, microbial biotransformation synthetic fluoroquinolone danofloxacin by ascomycete Xylaria longipes was investigated. Fungal submerged cultures led to a regioselective almost quantitative formation...

Direct unequal C-H bond difunctionalization of phosphorylated diamantane was achieved in high yield from the corresponding phosphonates. Reduction functionalized phosphonates provides access to novel primary and secondary alkyl/aryl phosphines. The prepared diamantyl phosphines are quite air stable compared their adamantyl especially alkyl or aryl analogues. This finding is corroborated by comparing singly occupied molecular orbital energy levels phosphine radical cations obtained density...