64506-21-4Relevant academic research and scientific papers
Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source
Biswas, Nandita,Srimani, Dipankar
, p. 10544 - 10554 (2021/07/31)
Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp3)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.
Application of Trimethylgermanyl-Substituted Bisphosphine Ligands with Enhanced Dispersion Interactions to Copper-Catalyzed Hydroboration of Disubstituted Alkenes
Xi, Yumeng,Su, Bo,Qi, Xiaotian,Pedram, Shayun,Liu, Peng,Hartwig, John F.
, p. 18213 - 18222 (2020/12/04)
We report the incorporation of large substituents based on heavy main-group elements that are atypical in ligand architectures to enhance dispersion interactions and, thereby, enhance enantioselectivity. Specifically, we prepared the chiral biaryl bisphosphine ligand (TMG-SYNPHOS) containing 3,5-bis(trimethylgermanyl)phenyl groups on phosphorus and applied this ligand to the challenging problem of enantioselective hydrofunctionalization reactions of 1,1-disubtituted alkenes. Indeed, TMG-SYNPHOS forms a copper complex that catalyzes hydroboration of 1,1-disubtituted alkenes with high levels of enantioselectivity, even when the two substituents are both primary alkyl groups. In addition, copper catalysts bearing ligands possessing germanyl groups were much more active for hydroboration than one derived from DTBM-SEGPHOS, a ligand containing 3,5-di-tert-butyl groups and widely used for copper-catalyzed hydrofunctionalization. This observation led to the identification of DTMGM-SEGPHOS, a bisphosphine ligand bearing 3,5-bis(trimethylgermanyl)-4-methoxyphenyl groups as the substituents on the phosphorus, as a new ligand that forms a highly active catalyst for hydroboration of unactivated 1,2-disubstituted alkenes, a class of substrates that has not readily undergone copper-catalyzed hydroboration previously. Computational studies revealed that the enantioselectivity and catalytic efficiency of the germanyl-substituted ligands is higher than that of the silyl and tert-butyl-substituted analogues because of attractive dispersion interactions between the bulky trimethylgermanyl groups on the ancillary ligand and the alkene substrate and that Pauli repulsive interactions tended to decrease enantioselectivity.
Nickel-Catalyzed Asymmetric Kumada Cross-Coupling of Symmetric Cyclic Sulfates
Eno, Meredith S.,Lu, Alexander,Morken, James P.
, p. 7824 - 7827 (2016/07/11)
Nickel-catalyzed enantioselective cross-couplings between symmetric cyclic sulfates and aromatic Grignard reagents are described. These reactions are effective with a broad range of substituted cyclic sulfates and deliver products with asymmetric tertiary carbon centers. Mechanistic experiments point to a stereoinvertive SN2-like oxidative addition of a nickel complex to the electrophilic substrate.
Vinyl polymerization versus [1,3] O to C rearrangement in the ruthenium-catalyzed reactions of vinyl ethers with hydrosilanes
Harada, Nari-Aki,Nishikata, Takashi,Nagashima, Hideo
supporting information; experimental part, p. 3243 - 3252 (2012/06/01)
Two reactions, vinyl polymerization and [1,3] O to C rearrangement of vinyl ethers, are investigated in the ruthenium-catalyzed reaction with hydrosilanes. The reaction pathways are dependent on the substituents of the vinyl ether, in particular, those of the alkoxy group. Primary-, secondary-, and tertiary-alkyl vinyl ethers, ROCHCH2, are polymerized with ease to give the corresponding polymer in good yields. When R is electron-donating benzyl groups, the reaction does not give the polyvinyl ether but results in [1,3] O to C rearrangement to give the corresponding aldehyde, RCH2CHO in moderate to good yields. The rearrangement selectively proceeds when vinyl ethers having α-substituents are used as the starting materials to give the corresponding ketones in high yields. With catalytic amounts of hydrosilanes, the rearrangement gives ketones or aldehydes selectively. In sharp contrast, use of excess amounts of hydrosilanes leads to the rearrangement followed by reduction of the formed carbonyl group to give the corresponding silyl ethers in good yields. Nature of catalytically active species is discussed. Crown Copyright
Chemoenzymatic synthesis of (+)-α-polypodatetraene and methyl (5R,10R,13R)-labda-8-en-15-oate
Kinoshita, Masako,Miyake, Takahiro,Arima, Yuusuke,Oguma, Minako,Akita, Hiroyuki
, p. 118 - 123 (2008/09/17)
The reported enzymatic resolution products {acetate of (1S,4aS,8aS)-1,2,3, 4,4a,5,6,7,8,8a-decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2- ethylene acetal} (8aS)-5 (>99% ee)] and [(1R,4aR,8aR)-1,2,3,4,4a,5,6,7,8,8a- decahydro-5,5,8a-trimethyl-2-oxo-trans-naphthalene-1-methanol-2-ethylene acetal (8aR)-4 (98% ee) were converted to (+)-α-polypodatetraene (1) and methyl (5R,10R,13R)-labda-8-en-15-oate (2), respectively. For the synthesis of (5R,10R,13R)-2, chiral isoprene congener (3S)-26 corresponding to the right part of 2 was synthesized based on the lipase-assisted resolution of (±)-2-methyl-3- (p-methoxyphenyl)propanol (17).
Diastereoselective electrophilic substitution of γ-oxy-substituted benzyllithiums
Arrica, Maria A,Azzena, Ugo,Pilo, Luciano,Piras, Elisabetta
, p. 5137 - 5139 (2007/10/03)
Reductive lithiation of diastereoisomeric mixtures of 4-aryl-5-methyl-1,3-dioxanes occurs with epimerization at the benzylic centre. Reaction of intermediate organometals with alkyl halides or CO2 afforded 2-methyl-3-substituted-3-phenylpropan-1-ols, or the corresponding lactones, with satisfactory yields and satisfactory to high diastereoselectivities. Observed diastereoselectivities strongly depend on the substitution pattern of starting materials.
Conformational Analysis of 1,1,2-Trisubstituted Ethanes by PMR: Part I - 3-Aryl-2-methylpropanols
Somasekharan, K. N.,Kiefer, Edgar F.
, p. 29 - 37 (2007/10/02)
A self-consistent model for the conformational analysis of 1,1,2-trisubstituted ethanes is developed, based on the temperature dependence of vicinal proton-proton coupling constants.Synthesis of racemates of 2(R), 3(S)- and 2(S), 3(R)-2,3-dideutero-2-methyl-3-phenyl-1-propanols is accomplished using known reactions of well-defined stereochemistry.By comparing the PMR spectra of undeuterated and deuterated compounds, an unequivocal assignment of benzylic protons is made.Concentration and variable-temperature studies have revealed the existence of very weak intramolecular interaction in three alcohols, p-R-C6H4-CH2-CHMe-CH2-OH, where R = NO2, H and OMe.
