928-95-0Relevant articles and documents
Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes
Huang, Jiaxin,Li, Jie,Yang, Wen,Zhang, Kezhuo,Zhao, Pei,Zhao, Wanxiang
supporting information, p. 302 - 305 (2022/01/03)
The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.
Cationic Ru complexes anchored on POM via non-covalent interaction towards efficient transfer hydrogenation catalysis
Chen, Manyu,Cui, Kai,Hou, Zhenshan,Peng, Qingpo,Wang, Jiajia,Wei, Xinjia,Zhao, Xiuge
, (2021/12/22)
The ionic materials consisting of cationic Ru complexes and Wells-Dawson polyoxometalate anion (POM, K6P2W18O62) have been constructed via a non-covalent interaction. The as-synthesized catalysts have been characterized thoroughly by NMR, XRD, FESEM, and FT-IR, etc. The characterization suggested that a hydrogen bond interaction occurred between the proton of the amine ligand in the cationic Ru complexes and the oxygen atom of the POM anion. The hydrogen bond played an important role in enhancing catalytic activity for the transfer hydrogenation of methyl levulinate (ML) to γ-valerolactone (GVL) under very mild conditions. Especially, the transfer hydrogenation reaction proceeded via a heterogeneous catalysis approach and the heterogenized catalysts even afforded much better catalytic performance than homogeneous analogs. Notably, the catalysts can be recycled without an obvious loss of activity, and further extended to highly selective transfer hydrogenation of α,β-unsaturated ketones and aldehydes, etc. into the corresponding α,β-unsaturated alcohols without any base external additives. The high catalytic performance of these anchored catalysts was highly related to the hydrogen bond interaction and the basicity of the polyanion. The obtained knowledge from this work could lead us to a new catalysis concept of tethering active homogeneous complexes for constructing highly active anchored Ru complex catalysts for hydrogenation reaction.
Regio- And diastereoselective Pd-catalyzed aminochlorocyclization of allylic carbamates: scope, derivatization, and mechanism
Ariga, Elaine Miho,Carita Correra, Thiago,Matsushima, Jullyane Emi,McIndoe, J. Scott,Moreira Ribeiro, Francisco Wanderson,Omari, Isaac,Papa Spadafora, Bruna,Rodrigues, Alessandro,Soares, Priscila Machado Arruda,Vinhato, Elisangela,de Oliveira-Silva, Diogo
supporting information, p. 5595 - 5606 (2021/07/02)
The regio- and diastereoselective synthesis of oxazolidinonesviaa Pd-catalyzed vicinal C-N/C-Cl bond-forming reaction from internal alkenes of allylic carbamates is reported. The oxazolidinones are obtained in yields of 44 to 95% with high to excellent diastereoselectivities (from 6?:?1 to >20?:?1 dr) from readily available precursors. This process is scalable, and the products are suitable for the synthesis of useful amino alcohols. A detailed theoretical and experimental mechanistic study was carried out to describe that the reaction proceeds through ananti-aminopalladation of the alkene followed by an oxidative C-Pd(ii) cleavage with retention of the carbon stereochemistry to yield the major diastereomer. The role of Cu(ii) in a C-Cl bond-forming mechanism step has also been proposed.
Selective, base-free hydrogenation of aldehydes catalyzed by IR complexes based on proton-responsive lutidine-derived CNP ligands
álvarez, Eleuterio,Hernández-Juárez, Martín,López-Serrano, Joaquín,Paneque, Margarita,Rendón, Nuria,Sánchez, Práxedes,Suárez, Andrés
, p. 1314 - 1327 (2021/05/31)
Metal catalysts based on ligands containing proton-responsive sites have found widespread applications in the hydrogenation of polar unsaturated substrates. In this contribution, Ir complexes incorporating lutidine-derived CNP (C = N-heterocyclic carbene, NHC; P = phosphine) pincer ligands with two nonequivalent Br?nsted acid/base sites have been examined in the hydrogenation of aldehydes. To this end, Ir(CNP)H2Cl complexes were synthesized in two steps from the CNP ligand precursors and Ir(acac)(COD). These derivatives react with an excess of NaH to yield the trihydride derivatives Ir(CNP)H3, which were assessed as catalyst precursors in the hydrogenation of a series of aldehydes. The catalytic reactions were performed using commercial-grade substrates under neutral, mild conditions (0.1 mol % Ir-CNP; 4 bar H2, room temperature) with high conversions and selectivities for the reduction of the carbonyl function in the presence of other readily reducible groups such as C=C, nitro, and halogens. Reaction of an Ir(CNP)H2Cl complex with base in the presence of an aromatic aldehyde produces the reversible formation of alkoxide Ir complexes in which the aldehyde is bound to the deprotonated pincer framework (CNP*) through the CH-NHC arm of the ligand. These species, along with a carboxylate complex resulting from the Ir mediated oxidation of the aldehyde by water, is observed in the reaction of Ir(CNP)H3 with benzaldehyde. Finally, investigation of the mechanism of the hydrogenation of aldehydes has been carried out by means of DFT calculations considering the involvement of each arm of the Ir-CNP/CNP* derivatives. Calculations support a mechanism in which the catalyst switches its metal?ligand cooperation sites to follow the lowest energy pathway for each step of the catalytic cycle.
A Cationic Ru(II) Complex Intercalated into Zirconium Phosphate Layers Catalyzes Selective Hydrogenation via Heterolytic Hydrogen Activation
Chen, Manyu,Xia, Jie,Li, Huan,Zhao, Xiuge,Peng, Qingpo,Wang, Jiajia,Gong, Honghui,Dai, Sheng,An, Pengfei,Wang, Haifeng,Hou, Zhenshan
, p. 3801 - 3814 (2021/08/03)
Catalytic hydrogenations constitute economic and clean transformations to produce pharmaceutical and a multitude of fine chemicals in chemical industry. Herein, we report a cationic Ru(II) complex intercalated into zirconium phosphate (ZrP) layers that enables the efficient catalytic conversion of furfural and other biomass-derived carbonyl compounds into the corresponding alcohols through selective hydrogenation of C=O group. The ZrP layers acted not only as a support for the Ru-complex, but also as the new ligands to tune the Ru(II) center via forming Ru?O bond. The resulting catalysts exhibit excellent catalytic performance and can be easily recycled for six times without significant loss of activity and selectivity. The Ru(II) complex-intercalated catalysts have been characterized by XRD, SEM, HRTEM, HAADF-STEM, XPS, FT-IR, DR-UV/Vis, EXAFS and XANES. Especially, it is observed that the appropriate interlayer spacing between ZrP layers is favorable to stabilize the Ru(II) complex. Notably, on the basis of the further characterization and density functional theory (DFT) calculation, it is identified that the interaction of cationic Ru(II) complex and P?OH group within ZrP layers leads to the high catalytic performance in selective hydrogenation, and the newly formed Ru?O?P species plays a crucial role in the heterolytic hydrogen activation and selective hydrogenation of biomass-derived compounds containing a carbonyl group.
First synthesis of 3-S-glutathionylhexanal-d8 and its bisulfite adduct
Muhl, Jennifer R.,Pilkington, Lisa I.,Deed, Rebecca C.
supporting information, (2020/06/17)
3-Sulfanylhexan-1-ol (3SH) is an impact odorant of white wines, imparting tropical fruit aromas. A reliable synthetic pathway to 3-S-glutathionylhexanal (glut-3SH-al), a precursor to 3SH that has not been intensively studied, was developed starting from 1-butanol. Application of this synthesis to 1-butanol-d10, conserved eight deuteriums, producing glut-3SH-al-d8, which can be used as an internal standard for future work on the occurrence and evolution of glut-3SH-al in wine systems. Additionally, both glut-3SH-SO3 and glut-3SH-SO3-d8 were synthesised from the corresponding aldehyde, enabling further study of the role of these bisulfite adducts in 3SH biogenesis.
Visible-Light-Promoted Intramolecular α-Allylation of Aldehydes in the Absence of Sacrificial Hydrogen Acceptors
Liu, Feng,Liu, Jia-Li,tu, Jia-Lin
supporting information, p. 7369 - 7372 (2020/10/05)
We report herein an unprecedented protocol for radical cyclization of aldehydes with pendant alkenes via synergistic photoredox, cobaloxime, and amine catalysis. The transformation was achieved in the absence of external oxidants, providing a variety of 5-, 6-, and 7-membered ring products with alkene transposition in satisfactory yields. The reaction exhibits wide functional group compatibility and occurs under mild conditions with extrusion of H2.
Copper-Catalyzed Azide–Ynamide Cyclization to Generate α-Imino Copper Carbenes: Divergent and Enantioselective Access to Polycyclic N-Heterocycles
Chen, Yang-Bo,Deng, Chao,Liu, Rai-Shung,Liu, Xin,Luo, Chen,Wang, Ze-Shu,Ye, Long-Wu,Zhai, Tong-Yi,Zhang, Yi-Ping
supporting information, p. 17984 - 17990 (2020/08/21)
Here an efficient copper-catalyzed cascade cyclization of azide-ynamides via α-imino copper carbene intermediates is reported, representing the first generation of α-imino copper carbenes from alkynes. This protocol enables the practical and divergent synthesis of an array of polycyclic N-heterocycles in generally good to excellent yields with broad substrate scope and excellent diastereoselectivities. Moreover, an asymmetric azide–ynamide cyclization has been achieved with high enantioselectivities (up to 98:2 e.r.) by employing BOX-Cu complexes as chiral catalysts. Thus, this protocol constitutes the first example of an asymmetric azide–alkyne cyclization. The proposed mechanistic rationale for this cascade cyclization is further supported by theoretical calculations.
Biosynthesis of Mycotoxin Fusaric Acid and Application of a PLP-Dependent Enzyme for Chemoenzymatic Synthesis of Substituted l -Pipecolic Acids
Hai, Yang,Chen, Mengbin,Huang, Arthur,Tang, Yi
supporting information, p. 19668 - 19677 (2020/12/01)
Fusaric acid (FA) is a well-known mycotoxin that plays an important role in plant pathology. The biosynthetic gene cluster for FA has been identified, but the biosynthetic pathway remains unclarified. Here, we elucidated the biosynthesis of FA, which features a two-enzyme catalytic cascade, a pyridoxal 5′-phosphate (PLP)-dependent enzyme (Fub7), and a flavin mononucleotide (FMN)-dependent oxidase (Fub9) in synthesizing the picolinic acid scaffold. FA biosynthesis also involves an off-line collaboration between a highly reducing polyketide synthase (HRPKS, Fub1) and a nonribosomal peptide synthetase (NRPS)-like carboxylic acid reductase (Fub8) in making an aliphatic α,β-unsaturated aldehyde. By harnessing the stereoselective C-C bond-forming activity of Fub7, we established a chemoenzymatic route for stereoconvergent synthesis of a series of 5-alkyl-, 5,5-dialkyl-, and 5,5,6-trialkyl-l-pipecolic acids of high diastereomeric ratio.
Synergistic Relay Reactions To Achieve Redox-Neutral α-Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
Kan, Jian,Li, Chao-Jun,Li, Chen-Chen,Li, Jianbin,Lv, Leiyang,Qiu, Zihang
supporting information, p. 4544 - 4549 (2020/02/04)
Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type “carbanions” and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.
