4829-02-1Relevant academic research and scientific papers
Catalytic Asymmetric Acyloin Rearrangements of α-Ketols, α-Hydroxy Aldehydes, and α-Iminols by N, N′-Dioxide-Metal Complexes
Dai, Li,Li, Xiangqiang,Zeng, Zi,Dong, Shunxi,Zhou, Yuqiao,Liu, Xiaohua,Feng, Xiaoming
, p. 5041 - 5045 (2020/07/03)
A highly enantioselective acyloin rearrangement of cyclic α-ketols has been developed with a chiral Al(III)-N,N′-dioxide complex as catalyst. This strategy provided an array of optically active 2-acyl-2-hydroxy cyclohexanones in moderate to good yields with high enantioselectivities. The asymmetric isomerizations of acyclic α-hydroxy aldehydes and α-iminols were achieved as well under modified conditions, affording the corresponding chiral α-hydroxy ketones and α-amino ketones in moderate results. Moreover, further transformations of product to enantioenriched diols were carried out.
Direct Asymmetric α-Hydroxylation of Cyclic α-Branched Ketones through Enol Catalysis
Shevchenko, Grigory A.,Pupo, Gabriele,List, Benjamin
, p. 49 - 53 (2019/01/04)
Enantiopure α-hydroxy carbonyl compounds are common scaffolds in natural products and pharmaceuticals. Although indirect approaches towards their synthesis are known, direct asymmetric methodologies are scarce. Herein, we report the first direct asymmetric α-hydroxylation of α-branched ketones through enol catalysis, enabling a facile access to valuable α-keto tertiary alcohols. The transformation, characterized by the use of nitrosobenzene as the oxidant and a new chiral phosphoric acid as the catalyst, delivers a good scope and excellent enantioselectivities.
An Unexpected α-Oxidation of Cyclic Ketones with 1,4-Benzoquinone by Enol Catalysis
Shevchenko, Grigory A.,Oppelaar, Barry,List, Benjamin
, p. 10756 - 10759 (2018/08/17)
The first direct and asymmetric α-aryloxylation of cyclic ketones via enol catalysis has been achieved using quinones as the reaction partners. Catalytic amounts of a phosphoric acid promote the exclusive formation of α,α-disubstituted ketones from the corresponding α-substituted ketones in good yields and enantioselectivities (up to 96.5:3.5 er). Preliminary mechanistic experiments suggest that this reaction proceeds via a proton-coupled electron transfer (PCET) followed by radical recombination.
Synthesis of tetrahydrobiphenylene via Pd(0)-catalyzed C(sp2)-H functionalization
Tsukano, Chihiro,Suetsugu, Satoshi,Muto, Nobusuke,Takemoto, Yoshiji
, p. 1167 - 1174 (2018/05/02)
Tetrahydrobiphenylene consists of cyclobutene fused with benzene and cyclohexene rings. In this paper, a direct method for synthesizing tetrahydrobiphenylenes based on a palladium (Pd)(0)-catalyzed C(sp2)-H functionalization was investigated. The developed method was applied to the synthesis of several tetrahydrobiphenylenes having an oxygen functionality at the ring juncture. The derivatization of a tetrahydrobiphenylene is also reported.
Iron(iii) chloride hexahydrate-promoted selective hydroxylation and chlorination of benzyl ketone derivatives for the construction of hetero-quaternary scaffolds
Chen, Tao,Peng, Rui,Hu, Wenxin,Zhang, Fu-Min
supporting information, p. 9859 - 9867 (2016/10/31)
A novel and tunable α-hydroxylation/α-chlorination of benzyl ketone derivatives has been developed for the construction of hetero-quaternary carbon centers by iron(iii) chloride hexahydrate mediated selective transformations through the application of dif
Oxidative cleavage of olefins by in situ-generated catalytic 3,4,5,6-tetramethyl-2-iodoxybenzoic acid/oxone
Moorthy, Jarugu Narasimha,Parida, Keshaba Nanda
, p. 11431 - 11439 (2015/02/05)
Oxidative cleavage of a variety of olefins to the corresponding ketones/carboxylic acids is shown to occur in a facile manner with 3,4,5,6-tetramethyl-2-iodobenzoic acid (TetMe-IA)/oxone. The simple methodology involves mere stirring of the olefin and catalytic amount (10 mol %) of TetMe-IA and oxone in acetonitrile-water mixture (1:1, v/v) at rt. The reaction mechanism involves initial dihydroxylation of the olefin with oxone, oxidative cleavage by the in situ-generated 3,4,5,6-tetramethyl-2-iodoxybenzoic acid (TetMe-IBX), and oxidation of the aldehyde functionality to the corresponding acid with oxone. Differences in the reactivities of electron-rich and electron-poor double bonds have been exploited to demonstrate chemoselective oxidative cleavage in substrates containing two double bonds.
Enantioselective titanium(III)-catalyzed reductive cyclization of ketonitriles
Streuff, Jan,Feurer, Markus,Bichovski, Plamen,Frey, Georg,Gellrich, Urs
supporting information; experimental part, p. 8661 - 8664 (2012/09/21)
Reduction, please! The title reaction affords ?-hydroxyketones, a common structural motif in biologically active natural products, in good yields and high enantioselectivities at room temperature. The commercially available ansa-titanocene 1 was found to be an efficient catalyst for this process, which presumably proceeds by addition of a ketyl radical to a nitrile.
Improved methods for thermal rearrangement of alicyclic α-hydroxyimines to α-aminoketones: Synthesis of ketamine analogues as antisepsis candidates
Elhawi, Hagit,Eini, Hadar,Douvdevani, Amos,Byk, Gerardo
, p. 6784 - 6807 (2012/09/07)
Ketamine is an analgesic/anesthetic drug, which, in combination with other drugs, has been used as anesthetic for over 40 years. Ketamine induces its analgesic activities by blocking the N-methyl-D-aspartate (NMDA) receptor in the central nervous system (CNS). We have reported that low doses of ketamine administrated to patients before incision significantly reduced post-operative inflammation as reflected by reduced interleukin-6 (IL-6) sera-levels. Our data demonstrated in a rat model of Gram-negative bacterial-sepsis that if we inject a low dose of ketamine following bacterial inoculation we reduce mortality from approximately 75% to 25%. Similar to what we have observed in operated patients, the levels of TNF-α and IL-6 in ketamine-treated rats were significantly lower than in septic animals not treated with ketamine. On the base of these results, we have designed and synthesized series of new analogues of ketamine applying a thermal rearrangement of alicyclic α-hydroxyimines to α-aminoketones in parallel arrays. One of the analogues (compound 6e) displayed high activity in down-regulating the levels of IL-6 and TNF-α in vivo as compared to ketamine.
Mg-promoted facile and selective intramolecular cyclization of aromatic δ-ketoesters
Miyazaki, Takeshi,Maekawa, Hirofumi,Yonemura, Kazuaki,Yamamoto, Yoshimasa,Yamanaka, Yoshiko,Nishiguchi, Ikuzo
experimental part, p. 1598 - 1602 (2011/03/22)
Treatment of various types of aromatic δ-ketoesters 2, 7, and 9 with Mg-turnings for Grignard reaction at -5 to 0 °C in N,N-dimethylformamide (DMF) containing trimethylsilyl chloride (TMSCl) brought about selective and reductive intramolecular cyclization
Asymmetric electrochemical oxidation of 1,2-diols, aminoalcohols, and?aminoaldehydes in the presence of chiral copper catalyst
Minato, Daishirou,Arimoto, Hitomi,Nagasue, Yoko,Demizu, Yosuke,Onomura, Osamu
, p. 6675 - 6683 (2008/12/20)
Asymmetric oxidation of 1,2-diols, aminoalcohols, and aminoaldehydes in the presence of copper(II) triflate and (R,R)-Ph-BOX was accomplished by electrochemical method using Br- as a mediator. This oxidation was applicable to kinetic resolution of racemic cis-cycloalkane-1,2-diols, aminoalcohols, and aminoaldehydes to afford optically active compounds with good to high enantioselectivity.
