583-03-9Relevant academic research and scientific papers
Lipase-catalyzed kinetic resolution of Z-configured homoallylic alcohols
Adam, Waldemar,Saha-Moeller, Chantu R.,Schmid, Katharina S.
, p. 315 - 322 (1999)
Racemic Z homoallylic alcohols were prepared by the BuSnCl3-catalyzed addition of aldehydes to 1-(tributylstannyl)-2-butene. These alcohols were resolved for the first time by lipase-catalyzed enantioselective acetylation in up to 98% enantiomeric purity.
Chain Walking as a Strategy for Iridium-Catalyzed Migratory Amidation of Alkenyl Alcohols to Access α-Amino Ketones
Baek, Seung Beom,Chang, Sukbok,Hwang, Yeongyu,Kim, Dongwook
supporting information, p. 4277 - 4285 (2022/03/08)
Catalytic carbon-nitrogen bond formation in hydrocarbons is an appealing synthetic tool to access valuable nitrogen-containing compounds. Although a number of synthetic approaches have been developed to construct a bifunctional α-amino carbonyl scaffold in this realm, installation of an amino functionality at the remote and unfunctionalized aliphatic sites remains underdeveloped. Here we present a tandem iridium catalysis that enables the redox-relay amidation of alkenyl alcohols via chain walking and metal-nitrenoid transfer, which eventually offers a new route to various α-amino ketones with excellent regioselectivity. The virtue of this transformation is that an unrefined isomeric mixture of alkenyl alcohols can be utilized as the readily available starting materials to lead to the regioconvergent amidation. Mechanistic investigations revealed that the reaction proceeds via a tandem process involving two key components of redox-relay chain walking and intermolecular nitrenoid transfer with the assistance of hydrogen bonding, thus representing the competence of Ir catalysis for the olefin migratory C-N coupling with high efficiency and exquisite selectivity.
Highly Active Cooperative Lewis Acid—Ammonium Salt Catalyst for the Enantioselective Hydroboration of Ketones
Titze, Marvin,Heitk?mper, Juliane,Junge, Thorsten,K?stner, Johannes,Peters, René
supporting information, p. 5544 - 5553 (2021/02/05)
Enantiopure secondary alcohols are fundamental high-value synthetic building blocks. One of the most attractive ways to get access to this compound class is the catalytic hydroboration. We describe a new concept for this reaction type that allowed for exceptional catalytic turnover numbers (up to 15 400), which were increased by around 1.5–3 orders of magnitude compared to the most active catalysts previously reported. In our concept an aprotic ammonium halide moiety cooperates with an oxophilic Lewis acid within the same catalyst molecule. Control experiments reveal that both catalytic centers are essential for the observed activity. Kinetic, spectroscopic and computational studies show that the hydride transfer is rate limiting and proceeds via a concerted mechanism, in which hydride at Boron is continuously displaced by iodide, reminiscent to an SN2 reaction. The catalyst, which is accessible in high yields in few steps, was found to be stable during catalysis, readily recyclable and could be reused 10 times still efficiently working.
Homoleptic cobalt(II) phenoxyimine complexes for hydrosilylation of aldehydes and ketones without base activation of cobalt(II)
Hori, Momoko,Ishikawa, Ryuta,Koga, Yuji,Matsubara, Kouki,Mitsuyama, Tomoaki,Shin, Sayaka
, p. 1379 - 1387 (2021/05/29)
Air-stable, easy to prepare, homoleptic cobalt(II) complexes bearing pendant-modified phenoxyimine ligands were synthesized and determined. The complexes exhibited high catalytic performance for reducing aldehydes and ketones via catalytic hydrosilylation, where a hydrosilane and a catalytic amount of the cobalt(II) complex were added under base-free conditions. The reaction proceeded even in the presence of excess water, and excellent functional-group tolerance was observed. Subsequent hydrolysis gave the alcohol in high yields. Moreover, H2O had a critical role in activation of the Co(II) catalyst with hydrosilane. Several additional results also indicated that the cobalt(II) center acts as an active catalyst in the hydrosilylation of aldehydes and ketones.
Base-induced Sommelet–Hauser rearrangement of N-(α-(2-oxyethyl)branched)benzylic glycine ester-derived ammonium salts via a chelated intermediate
Baba, Souya,Hirano, Kazuki,Tayama, Eiji
supporting information, (2020/03/13)
The base-induced Sommelet–Hauser (S–H) rearrangement of N-(α-branched)benzylic glycine ester-derived ammonium salts 1 was investigated. When the α-branched substituent was a simple alkyl, such as a methyl or butyl, desired S–H rearrangement product 2 was obtained in low yield with formation of the [1,2] Stevens rearranged 4 and Hofmann eliminated products 5 and 6. However, when the α-branched substituent had a 2-oxy moiety, such as 2-acetoxyethyl or 2-benzoyloxyethyl, the yields of 2 were improved. These results could be explained by formation of chelated intermediate C that stabilizes the carbanionic ylide, and the subsequent initial dearomative [2,3] sigmatropic rearrangement would be accelerated. The existence of C was supported by mechanistic experiments. This enhancement effect is not very strong or effective; however, it will expand the synthetic usefulness of ammonium ylide rearrangements.
SOLVENTS FOR ORGANOMETALLIC REAGENTS
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Paragraph 0017; 0033; 0034; 0049, (2020/02/23)
In an embodiment, the present disclosure pertains to a solvent including a hydrocarbon oligomer with at least 20 carbon atoms, where the hydrocarbon oligomer has at least one of a low viscosity, a low vapor pressure, and a high flashpoint. In another embodiment, the present disclosure pertains to a solution including a poly(α-olefin) and a reactive organometallic reagent. In a further embodiment, the present disclosure pertains to a solution including an oligomeric hydrocarbon and a reactive organometallic reagent. In an additional embodiment, the present disclosure pertains to a method for creating a solution, where the method includes adding a reactive organometallic reagent to an oligomeric hydrocarbon.
Efficient Transfer Hydrogenation of Ketones using Methanol as Liquid Organic Hydrogen Carrier
Garg, Nidhi,Paira, Soumen,Sundararaju, Basker
, p. 3472 - 3476 (2020/05/29)
Herein, we demonstrate an efficient protocol for transfer hydrogenation of ketones using methanol as practical and useful liquid organic hydrogen carrier (LOHC) under Ir(III) catalysis. Various ketones, including electron-rich/electron-poor aromatic ketones, heteroaromatic and aliphatic ketones, have been efficiently reduced into their corresponding alcohols. Chemoselective reduction of ketones was established in the presence of various other reducible functional groups under mild conditions.
Enzymatic Primary Amination of Benzylic and Allylic C(sp3)-H Bonds
Jia, Zhi-Jun,Gao, Shilong,Arnold, Frances H.
supporting information, p. 10279 - 10283 (2020/07/27)
Aliphatic primary amines are prevalent in natural products, pharmaceuticals, and functional materials. While a plethora of processes are reported for their synthesis, methods that directly install a free amine group into C(sp3)-H bonds remain unprecedented. Here, we report a set of new-to-nature enzymes that catalyze the direct primary amination of C(sp3)-H bonds with excellent chemo-, regio-, and enantioselectivity, using a readily available hydroxylamine derivative as the nitrogen source. Directed evolution of genetically encoded cytochrome P411 enzymes (P450s whose Cys axial ligand to the heme iron has been replaced with Ser) generated variants that selectively functionalize benzylic and allylic C-H bonds, affording a broad scope of enantioenriched primary amines. This biocatalytic process is efficient and selective (up to 3930 TTN and 96percent ee), and can be performed on preparative scale.
A Practical and Stereoselective In Situ NHC-Cobalt Catalytic System for Hydrogenation of Ketones and Aldehydes
Zhong, Rui,Wei, Zeyuan,Zhang, Wei,Liu, Shun,Liu, Qiang
supporting information, p. 1552 - 1566 (2019/06/14)
Homogeneous catalytic hydrogenation of carbonyl groups is a synthetically useful and widely applied organic transformation. Sustainable chemistry goals require replacing conventional noble transition metal catalysts for hydrogenation by earth-abundant base metals. Herein, we report how a practical in situ catalytic system generated by easily available pincer NHC precursors, CoCl2, and a base enabled efficient and high-yielding hydrogenation of a broad range of ketones and aldehydes (over 50 examples and a maximum turnover number [TON] of 2,610). This is the first example of NHC-Co-catalyzed hydrogenation of C=O bonds using flexible pincer NHC ligands consisting of a N-H substructure. Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized by fine-tuning of the steric bulk of pincer NHC ligands. Additionally, a bis(NHCs)-Co complex was successfully isolated and fully characterized, and it exhibits excellent catalytic activity that equals that of the in-situ-formed catalytic system. Catalytic hydrogenation is a powerful tool for the reduction of organic compounds in both fine and bulk chemical industries. To improve sustainability, more ecofriendly, inexpensive, and earth-abundant base metals should be employed to replace the precious metals that currently dominate the development of hydrogenation catalysts. However, the majority of the base-metal catalysts that have been reported involve expensive, complex, and often air- and moisture-sensitive phosphine ligands, impeding their widespread application. From a mixture of the stable CoCl2, imidazole salts, and a base, our newly developed catalytic system that formed easily in situ enables efficient and stereoselective hydrogenation of C=O bonds. We anticipate that this easily accessible catalytic system will create opportunities for the design of practical base-metal hydrogenation catalysts. A practical in situ catalytic system generated by a mixture of easily available pincer NHC precursors, CoCl2, and a base enabled highly efficient hydrogenation of a broad range of ketones and aldehydes (over 50 examples and up to a turnover number [TON] of 2,610). Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized in high selectivities. Moreover, the preparation of a well-defined bis(NHCs)-Co complex via this pincer NHC ligand consisting of a N-H substructure was successful, and it exhibits equally excellent catalytic activity for the hydrogenation of C=O bonds.
Highly Focused Library-Based Engineering of Candida antarctica Lipase B with (S)-Selectivity Towards sec-Alcohols
Cen, Yixin,Li, Danyang,Xu, Jian,Wu, Qiongsi,Wu, Qi,Lin, Xianfu
supporting information, p. 126 - 134 (2018/12/05)
Candida antarctica lipase B (CALB) is one of the most extensively used biocatalysts in both academia and industry and exhibits remarkable (R)-enantioselectivity for various chiral sec-alcohols. Considering the significance of tailor-made stereoselectivity in organic synthesis, a discovery of enantiocomplementary lipase mutants with high (R)- and (S)-selectivity is valuable and highly desired. Herein, we report a highly efficient directed evolution strategy, using only 4 representative amino acids, namely, alanine (A), leucine (L), lysine (K), tryptophan (W) at each mutated site to create an extremely small library of CALB variants requiring notably less screening. The obtained best mutant with three mutations W104V/A281L/A282K displayed highly reversed (S)-selectivity towards a series of sec-alcohol with E values up to 115 (conv. 50%, ee 94%). Compared with the previously reported (S)-selective CALB variant, W104A, a single mutation provided less selectivity, while the synergistic effects of three mutations in the best variant endow better (S)-selectivity and a broader substrate scope than the W104A variant. Structural analysis and molecular dynamics simulation unveiled the source of reversed enantioselectivity. (Figure presented.).
