89-95-2Relevant articles and documents
Experimental and theoretical study of the effect of active-site constrained substrate motion on the magnitude of the observed intramolecular isotope effect for the P450 101 catalyzed benzylic hydroxylation of isomeric xylenes and 4,4'-dimethylbiphenyl
Audergon, Christian,Iyer, Krishna R.,Jones, Jeffrey P.,Darbyshire, John F.,Trager, William F.
, p. 41 - 47 (1999)
The validity of a cytochrome P450 (P450) 101 force field developed previously was tested by comparing to published results from other laboratories the predicted regioselectivity and stereoselectivity of both (R)- and (S)-norcamphor oxidation when the force field was used. Once validated, the force field was used to test the hypothesis that the magnitude of an observed intramolecular isotope effect is a function of the distance between equivalent but isotopically distinct intramolecular sites of oxidative attack. Molecular dynamics simulations and kinetic deuterium isotope effect experiments on benzylic hydroxylation were then conducted for a series of selectively deuterated isomeric xylenes and 4,4'-dimethylbiphenyl with P450 101. The molecular dynamics simulations predicted that the rank order of substrate mobility in the active site of P450 101 was o-xylene > p- xylene > dimethylbiphenyl. The observed isotope effects for the trideutero analogues were 10.6, 7.4, and 2.7, for the o-xylene, p-xylene, and 4,4'- dimethylbiphenyl, respectively. Thus, as the theoretically predicted rates of interchange between the isotopically distinct methyl groups decrease, the observed isotope effect decreases. The agreement between the theoretical predictions and experimental results provides strong support for the distance hypothesis stated above and for the potential of computational analysis to enhance our understanding of protein/small molecule interactions.
Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
, p. 5305 - 5316 (2021/04/12)
Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
Highly Modular Piano-Stool N-Heterocyclic Carbene Iron Complexes: Impact of Ligand Variation on Hydrosilylation Activity
Nylund, Pamela V. S.,Ségaud, Nathalie C.,Albrecht, Martin
, p. 1538 - 1550 (2021/05/29)
The piano-stool configuration combined with N-heterocyclic carbene (NHC) ligation constitutes an attractive scaffold for employing iron in catalysis. Here, we have expanded this scaffold by installing a pentamethyl cyclopentadienyl (Cp*) ligand as a strong electron donor compared to the traditionally used unsubstituted cyclopentadiene (Cp). Moreover, decarboxylation is introduced as a method to prepare these iron(II) NHC complexes, which avoids the isolation of air-sensitive free carbenes. In addition to the Cp/Cp? variation, the complexes have been systematically modulated at the NHC scaffold, the NHC wingtip groups, and the ancillary ligands in order to identify critical factors that govern the catalytic activity of the iron center in the hydrosilylation of aldehydes. These modulations reveal the importance of steric tailoring and optimization of electron density for high catalytic performance. The data demonstrate a critical role of the NHC scaffold with triazolylidenes imparting consistently higher activity than imidazolylidenes and a correlation between catalytic activity and steric rather than electronic factors. Moreover, the implementation of steric bulk is strongly dependent on the nature of the NHC and severely limited by the Cp? iron precursor. The best performing catalytic systems reach turnover frequencies, TOFmax's, of up to 360 h-1 at 60 °C. Mechanistic investigations by 1H NMR and in situ IR spectroscopies indicate a catalyst activation that involves CO release and aldehyde coordination to the [Fe(Cp)(NHC)I] fragment.
Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
supporting information, p. 6207 - 6227 (2021/05/06)
The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
A Water/Toluene Biphasic Medium Improves Yields and Deuterium Incorporation into Alcohols in the Transfer Hydrogenation of Aldehydes
Ruiz-Casta?eda, Margarita,Santos, Lucía,Manzano, Blanca R.,Espino, Gustavo,Jalón, Félix A.
supporting information, p. 1358 - 1372 (2021/03/16)
Deuterium labeling is an interesting process that leads to compounds of use in different fields. We describe the transfer hydrogenation of aldehydes and the selective C1 deuteration of the obtained alcohols in D2O, as the only deuterium source. Different aromatic, alkylic and α,β-unsaturated aldehydes were reduced in the presence of [RuCl(p-cymene)(dmbpy)]BF4, (dmbpy=4,4′-dimethyl-2,2′-bipyridine) as the pre-catalyst and HCO2Na/HCO2H as the hydrogen source. Moreover, furfural and glucose, were selectively reduced to the valuable alcohols, furfuryl alcohol and sorbitol. The processes were carried out in neat water or in a biphasic water/toluene system. The biphasic system allowed easy recycling, higher yields, and higher selective D incorporation (using D2O/toluene). The deuteration took place due to an efficient effective M–H/D+ exchange from D2O that allows the inversion of polarity of D+ (umpolung). DFT calculations that explain the catalytic behavior in water are also included.
Direct Heterogenization of the Ru-Macho Catalyst for the Chemoselective Hydrogenation of α,β-Unsaturated Carbonyl Compounds
Padmanaban, Sudakar,Gunasekar, Gunniya Hariyanandam,Yoon, Sungho
supporting information, p. 6881 - 6888 (2021/03/01)
In this study, a commercially available homogeneous pincer-type complex, Ru-Macho, was directly heterogenized via the Lewis acid-catalyzed Friedel-Crafts reaction using dichloromethane as the cross-linker to obtain a heterogeneous, pincer-type Ru porous organometallic polymer (Ru-Macho-POMP) with a high surface area. Notably, Ru-Macho-POMP was demonstrated to be an efficient heterogeneous catalyst for the chemoselective hydrogenation of α,β-unsaturated carbonyl compounds to their corresponding allylic alcohols using cinnamaldehyde as a model compound. The Ru-Macho-POMP catalyst showed a high turnover frequency (TOF = 920 h-1) and a high turnover number (TON = 2750), with high chemoselectivity (99%) and recyclability during the selective hydrogenation of α,β-unsaturated carbonyl compounds.
Synthesis, Docking, and Biological activities of novel Metacetamol embedded [1,2,3]-triazole derivatives
Battu, Satyanarayana,Joolakanti, Hima Bindhu,Kamepalli, Ramanjaneyulu,Miryala, Jeevanreddy
, (2021/06/18)
ERα controls the breast tissue development and progression of breast cancer. In our search for novel compounds to target Estrogen Receptor Alpha Ligand-Binding Domain, we identified “N-(3-((1H-1,2,3-triazol-4-yl)methoxy)phenyl)acetamide” derivatives as lead compounds. The Docking studies indicated good docking score for Metacetamol derivatives when docked into the 1XP6. A series of metacetamol derivatives have been synthesized, characterized and evaluated for cytotoxicity, anti bacterial and anti oxidant activities. Among the tested twelve hybrid compounds, “7a, 7g, 7h and 7i” derivatives showed promising cytotoxicity with IC50 value of 50 value of 30 μM, whereas Compounds “7a, 7b, 7c, 7d, 7g, 7j, 7k and 7l” showed moderate anti bacterial activity with the MIC value of 300 μM.
CeO2-nanocubes as efficient and selective catalysts for the hydroboration of carbonyl groups
Bhawar, Ramesh,Bose, Shubhankar Kumar,Patil, Kiran S.
, p. 15028 - 15034 (2021/09/04)
The CeO2-nanoparticle catalysed hydroboration of carbonyl compounds with HBpin (pin = OCMe2CMe2O) is reported to afford the corresponding borate esters in excellent yield. A series of aromatic and aliphatic aldehydes and ketones having synthetically important functional groups were well-Tolerated under mild reaction conditions. Further, chemoselective hydroboration of aldehydes over other reducible functional groups such as ketone, nitrile, hydroxide, alkene, alkyne, amide, ester, nitro, and halides was achieved. Importantly the catalyst can be recycled up to ten runs with slight loss in activity. This journal is
Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
An, Duk Keun,Jaladi, Ashok Kumar,Kim, Hyun Tae,Yi, Jaeeun
, (2021/11/17)
Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
Uranyl(VI) Triflate as Catalyst for the Meerwein-Ponndorf-Verley Reaction
Kobylarski, Marie,Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
supporting information, p. 16140 - 16148 (2021/11/01)
Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1-10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.
