149099-27-4Relevant articles and documents
Solvolytic Behavior of Aryl and Alkyl Carbonates. Impact of the Intrinsic Barrier on Relative Reactivities of Leaving Groups
Mati?, Mirela,Kati?, Matija,Denegri, Bernard,Kronja, Olga
, p. 7820 - 7831 (2017)
The effect of negative hyperconjugation on the solvolytic behavior of carbonate diesters has been investigated kinetically by applying the LFER equation log k = sf(Ef + Nf). The observation that carbonate diesters solvolyze faster than the corresponding carboxylates and that the enhancement of aromatic carbonates is more pronounced indicates that the negative hyperconjugation and π-resonance within the carboxylate moiety is operative in TS. The plots of ΔG? vs approximated ΔrG° for solvolysis of benzhydryl aryl/alkyl carbonates and benzhydryl carboxylates reveal that a given carbonate solvolyzes over the higher Marcus intrinsic barrier and over the earlier transition state than carboxylate that produces an anion of similar stability. Due to the lag in development of the electronic effects along the reaction coordinate, the impact of the intrinsic barrier on solvolytic behavior of carbonates is more important than in the case of carboxylates and phenolates. Consequently, the solvolytic reaction constants (sf) are generally lower for carbonates than for carboxylates. Because of considerable lower reaction constants of carbonates, an inversion of relative reactivities between aryl/alkyl carbonate and another leaving group of similar nucleofugality (Nf) may occur if the electrofuge moiety of a substrate is switched.
Synthetically useful mono-functionalizations of dihaloarenes via Rieke metals
Sell,Hanson,Rieke
, p. 2379 - 2386 (1994)
Reaction of dihalobenzenes and 2, 5-dibromothiophene with Rieke magnesium, Rieke zinc, and Rieke calcium at low temperature affords a monoorganometallic intermediate which upon subsequent treatment with an electrophile provides a mono-functionalized aromatic product in excellent chemical yield.
Solvolytic reactivity of 2,4-dinitrophenolates
Matic, Mirela,Denegri, Bernard,Kronja, Olga
, p. 6019 - 6024 (2010)
A series of X,Y-substituted benzhydryl 2,4-dinitrophenolates (DNP, 1-5) were subjected to solvolysis in various methanol/water, ethanol/water, and acetone/water mixtures at 25 °C. The linear free energy relationship (LFER) equation, logk = sf(Ef + Nf), was used to derive the nucleofuge-specific parameters (Nf and sf) for an SN1-type reaction. The magnitudes of nucleofugalities (N f) are around zero, indicating that DNP falls in the middle of the established nucleofugality scale. The slope parameters (sf) and the Gruenwald-Winstein mOTs parameters obtained demonstrate that benzhydryl DNPs solvolyze through a late transition state (TS) in which the negative charge delocalization causes considerably diminished solvation. Because of the late TS, the nucleofuge-specific slope parameters, sf, are relatively high, i.e., the logk vs. Ef plots are steeper than for most of the previously investigated leaving groups. This may lead to intersection of the logk vs. Ef plots that correspond to DNP and to some other leaving groups of similar reactivity, i.e., inversion of the relative reactivities may occur. Such inversion is shown here for DNPs and phenyl carbonates. The nucleofuge-specific parameters determined for 2,4-dinitrophenolate (DNP) according to LFER equation logk = sf (Nf + Ef) indicate that DNPs solvolyze via late TS in which intense charge delocalization occurs. DNPs with weaker electrofuges solvolyze slower than the same substrates with leaving groups of similar reactivity but lower sf, whereas strong electrofuges solvolyze faster.
Mechanisms for the oxidation of secondary alcohols by dioxoruthenium(VI) complexes
Wang, Zhao,Chandler, W. David,Lee, Donald G.
, p. 919 - 928 (1998)
Possible mechanisms for the oxidation of alcohols by dioxoruthenium(VI) complexes are critically evaluated. Rate constants for the reduction of trans-[(TMC)Ru(VI)(O)2]++ (TMC = 1,4,8,11-tetramethyl-1,4,8,11- tetraazacyclotetradecane) by substituted benzhydrols are correlated more satisfactorily with Hammett σ substituent constants (p = -1.44 ± 0.08, r2 = 0.98) than with σ+ substituent constants (ρ = -0.72 ± 0.11, r2 = 0.83). Similar observations for the oxidation of substituted benzyl alcohols have recently been reported, confirming that the transition state for these reactions is not carbocation-like. Primary deuterium isotope effects indicate that cleavage of the α-C-H bond is rate-limiting. The lack of an observable O-D isotope effect and the ease of oxidation of ethers indicates that the presence of a hydroxyl is not essential. The previously reported observation that cyclobutanol is quantitatively converted into cyclobutanone by dioxoruthenium(VI) complexes eliminates free-radical intermediates from consideration as part of the mechanism, and negative entropies of activation (-ΔS(+) = 96-137 J mol-1 K-1) suggest a structured transition state. Only two of eight possible reaction mechanisms considered were found to be consistent with the available data. A critical analysis of the available data indicates that a 2 + 2 (C - H + Ru = O) addition and a reaction initiated by ligand formation through the interaction of the reductant's HOMO with the oxidant's LUMO are the most likely reaction mechanisms.
Chemoselective carbonyl reduction of functionalised aldehydes and ketones to alcohols with sodium dithionite
Singh, Jasvinder,Kad, Goverdhan L.,Sharma, Munisha,Dhillon
, p. 2253 - 2257 (1998)
Sodium dithionite efficiently reduces carbonyl functionalities of functionalised aldehydes and ketones to corresponding alcohols in good yields without effecting the other functional groups in water/dioxane system at 85°C.
Light-driven MPV-type reduction of aryl ketones/aldehydes to alcohols with isopropanol under mild conditions
Cao, Dawei,Xia, Shumei,Pan, Pan,Zeng, Huiying,Li, Chao-Jun,Peng, Yong
supporting information, p. 7539 - 7543 (2021/10/12)
Alcohols are versatile structural motifs of pharmaceuticals, agrochemicals and fine chemicals. With respect to green chemistry, the development of more sustainable and cost-efficient processes for converting ketones/aldehydes to alcohols is highly desired. Herein, a direct light-driven strategy for reducing ketones/aldehydes to alcohols using isopropanol as the reducing agent and solvent, in the presence of t-BuOLi, under an air atmosphere at room temperature is developed. This operationally simple light-promoted Meerwein-Ponndorf-Verley (MPV) type reduction can be used to produce various benzylic alcohol derivatives as well as applied to bioactive molecules and PEEK model compounds, demonstrating its application potential.
Electronic Effect-Guided Rational Design of Candida antarctica Lipase B for Kinetic Resolution Towards Diarylmethanols
Li, Dan-Yang,Lou, Yu-Jiao,Xu, Jian,Chen, Xiao-Yang,Lin, Xian-Fu,Wu, Qi
supporting information, p. 1867 - 1872 (2021/02/12)
Herein, we developed an electronic effect-guided rational design strategy to enhance the enantioselectivity of Candida antarctica lipase B (CALB) mutants towards bulky pyridyl(phenyl)methanols. Compared to W104A mutant previously reported with reversed S-stereoselectivity toward sec-alcohols, three mutants (W104C, W104S and W104T) displayed significant improvement of S-enantioselectivity in the kinetic resolution (KR) of various phenyl pyridyl methyl acetates due to the increased electronic effects between pyridyl and polar residues. The electronic effects were also observed when mutating other residues surrounding the stereospecificity pocket of CALB, such as T42A, S47A, A281S or A281C, and can be used to manipulate the stereoselectivity. A series of bulky pyridyl(phenyl) methanols, including S-(4-chlorophenyl)(pyridin-2-yl) methanol (S-CPMA), the intermediate of bepotastine, were obtained in good yields and ee values. (Figure presented.).
Synthesis and biological evaluation of 1‐(Diarylmethyl)‐1h‐1,2,4‐triazoles and 1‐(diarylmethyl)‐1h‐imidazoles as a novel class of anti‐mitotic agent for activity in breast cancer
Ana, Gloria,Kelly, Patrick M.,Malebari, Azizah M.,Noorani, Sara,Nathwani, Seema M.,Twamley, Brendan,Fayne, Darren,O’boyle, Niamh M.,Zisterer, Daniela M.,Pimentel, Elisangela Flavia,Endringer, Denise Coutinho,Meegan, Mary J.
, p. 1 - 59 (2021/03/16)
We report the synthesis and biochemical evaluation of compounds that are designed as hybrids of the microtubule targeting benzophenone phenstatin and the aromatase inhibitor letrozole. A preliminary screening in estrogen receptor (ER)‐positive MCF‐7 breast cancer cells identified 5‐((2H‐1,2,3‐triazol‐1‐yl)(3,4,5‐trimethoxyphenyl)methyl)‐2‐methoxyphenol 24 as a potent antiproliferative compound with an IC50 value of 52 nM in MCF‐7 breast cancer cells (ER+/PR+) and 74 nM in triple‐negative MDA‐MB‐231 breast cancer cells. The compounds demonstrated significant G2/M phase cell cycle arrest and induction of apoptosis in the MCF‐7 cell line, inhibited tubulin polymerisation, and were selective for cancer cells when evaluated in non-tumorigenic MCF‐10A breast cells. The immunofluorescence staining of MCF‐7 cells confirmed that the compounds targeted tubulin and induced multinucleation, which is a recognised sign of mitotic catastrophe. Computational docking studies of compounds 19e, 21l, and 24 in the colchicine binding site of tubulin indicated potential binding conformations for the compounds. Compounds 19e and 21l were also shown to selectively inhibit aromatase. These compounds are promising candidates for development as antiproliferative, aromatase inhibitory, and microtubule‐disrupting agents for breast cancer.
Enhanced catalytic activity of one-dimensional CdS @TiO2 core-shell nanocomposites for selective organic transformations under visible LED irradiation
Eskandari, Parvin,Kazemi, Foad,Ramdar, Moosa,Zand, Zahra
, (2021/07/10)
In this study, we are interested in the photocatalytic activity under visible LED irradiation of one- dimensional (1D) CdS @TiO2 core–shell nanocomposites (CSNs) prepared through a facile and convenient method. For the synthesis of 1D CdS@TiO2 core/shell structure, titania source (Tetrabutyl titanate) was hydrolyzed by water vapor transmission on the surface of CdS nanowires (NWs) which were prepared via solvothermal method. The characterization of 1D CdS@TiO2 core–shell nanocomposites (CdS@TiO2 CSNs) was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy, and UV–Vis diffuse reflectance spectroscopy (DRS). The as-synthesized sample was utilized for the selective reduction of nitro compounds to benzimidazole and anilide, and also the reduction of benzophenones to alcohol under blue LED irradiation. The 1D CdS@TiO2 CSNs exhibited enhanced photoactivity compared with the pure TiO2, CdS nanowires and commercial TiO2-P25. The excellent reusability of the photocatalyst was examined for six runs. The results demonstrated that the prepared sample has the potential to provide a promising visible light-driven photocatalyst for other organic transformations.
Melamine-Based Porous Organic Polymers Supported Pd(II)-Catalyzed Addition of Arylboronic Acids to Aromatic Aldehydes
Shen, Kai,Wen, Min,Fan, Chaogang,Lin, Shaohui,Pan, Qinmin
, p. 2612 - 2621 (2021/01/15)
Abstract: A new type melamine-based porous organic polymers (SZU-1) has been synthesized with melamine and 2,2′-bipyridyl-5,5′-dialdehyde by a one-pot method and fully characterized. Divalent palladium salts were coordinated to this polymer network which successfully catalyzed the nucleophilic addition reaction of arylboronic acids to aromatic aldehydes. With only 1.0?mol% heterogeneous catalyst loading, high reaction yields (>?85%) can be achieved in most cases. The scope of substrates was also investigated and the catalyst showed universal applicability. Graphic Abstract: The loose and porous melamine-based porous organic polymers (SZU-1) are synthesized by melamine and 2,2′-bipyridyl-5,5′-dialdehyde. The performance of SZU-1 was characterized and most of the substrates achieved high yield (> 85%) in the catalytic performance test.[Figure not available: see fulltext.]
