54783-72-1Relevant academic research and scientific papers
A Concise Synthesis of the Key Tetrahydrofuran Moieties of Caruifolin A and EBC-342
Fernandes, Rodney A.,Bethi, Venkati
, p. 6922 - 6928 (2020)
A common strategy for the concise synthesis of the key tetrahydrofuran moieties of caruifolin A and EBC-342 is presented. Asymmetric dihydroxylation and intramolecular SN2-cyclization are key strategic reactions for the synthesis of the furan f
A Unified Synthetic Approach to Optically Pure Curvularin-Type Metabolites
Allu, Srinivasa Rao,Banne, Sreenivas,Jiang, Jia,Qi, Na,Guo, Jian,He, Yun
, p. 7227 - 7237 (2019/06/07)
A unified and concise approach to the synthesis of nine curvularin-type metabolites and two analogues has been developed with few steps and high yields. Among them, sumalactones A-D were synthesized for the first time. The key steps in this approach inclu
A Br?nsted Acid Catalyzed Cascade Reaction for the Conversion of Indoles to α-(3-Indolyl) Ketones by Using 2-Benzyloxy Aldehydes
Banerjee, Ankush,Maji, Modhu Sudan
supporting information, p. 11521 - 11527 (2019/08/16)
A Br?nsted acid catalyzed, operationally simple, scalable route to several functionalized α-(3-indolyl) ketones has been developed and the long-standing regioisomeric issue has been eliminated by choosing appropriate carbonyls. A readily available and cheap bottle reagent was used as the catalyst. This protocol was also applicable to the synthesis of densely functionalized α-(3-pyrrolyl) ketones. A detailed mechanistic study confirmed the involvement of enolether as a reaction intermediate. Several postsynthetic modifications along with easy access to β-carboline, tryptamines, tryptophols, and spiro-indolenine proclaim the synthetic utility of this powerful building block. On the basis of this concept, functionalized carbazoles were constructed by a cascade annulation strategy.
De novo synthesis of novel bacterial monosaccharide fusaminic acid
Wei, Ruohan,Liu, Han,Li, Xuechen
, p. 420 - 431 (2019/03/29)
Fusobacterium nucleatum is an oral bacteria related to various types of diseases. As Gram-negative bacteria, lipopolysaccharide (LPS) of Fusobacterium nucleatum could be a potential virulence factor. Recently, the structure of O-antigen in LPS of Fusobact
Synergistic substrate and catalyst effects in the addition of trimethylsilyl cyanide to imines derived from lactic acid
Fields, Alexander M.,Jones, Simon
, p. 3413 - 3420 (2019/05/16)
Trimethylsilylcyanide was added to various imines derived from (2S)-ethyl lactate in the presence of Lewis acids to provide both syn- and anti- β-hydroxy-α-aminonitrile stereoisomers. Syn-products were found to be the major in most instances, however, ant
Steric Enforcement of cis-Epoxide Formation in the Radical C-O-Coupling Reaction by Which (S)-2-Hydroxypropylphosphonate Epoxidase (HppE) Produces Fosfomycin
Zhou, Shengbin,Pan, Juan,Davis, Katherine M.,Schaperdoth, Irene,Wang, Bo,Boal, Amie K.,Krebs, Carsten,Bollinger, J. Martin
supporting information, p. 20397 - 20406 (2019/12/27)
(S)-2-Hydroxypropylphosphonate [(S)-2-HPP, 1] epoxidase (HppE) reduces H2O2 at its nonheme-iron cofactor to install the oxirane "warhead" of the antibiotic fosfomycin. The net replacement of the C1 pro-R hydrogen of 1 by its C2 oxygen, with inversion of configuration at C1, yields the cis-epoxide of the drug [(1R,2S)-epoxypropylphosphonic acid (cis-Fos, 2)]. Here we show that HppE achieves ～95% selectivity for C1 inversion and cis-epoxide formation via steric guidance of a radical-coupling mechanism. Published structures of the HppE·FeII·1 and HppE·ZnII·2 complexes reveal distinct pockets for C3 of the substrate and product and identify four hydrophobic residues - Leu120, Leu144, Phe182, and Leu193 - close to C3 in one of the complexes. Replacement of Leu193 in the substrate C3 pocket with the bulkier Phe enhances stereoselectivity (cis:trans ～99:1), whereas the Leu120Phe substitution in the product C3 pocket diminishes it (～82:18). Retention of C1 configuration and trans-epoxide formation become predominant with the bulk-reducing Phe182Ala substitution in the substrate C3 pocket (～13:87), trifluorination of C3 (～23:77), or both (～1:99). The effect of C3 trifluorination is counteracted by the more constrained substrate C3 pockets in the Leu193Phe (～56:44) and Leu144Phe/Leu193Phe (～90:10) variants. The ability of HppE to epoxidize substrate analogues bearing halogens at C3, C1, or both is inconsistent with a published hypothesis of polar cyclization via a C1 carbocation. Rather, specific enzyme-substrate contacts drive inversion of the C1 radical - as proposed in a recent computational study - to direct formation of the more potently antibacterial cis-epoxide by radicaloid C-O coupling.
Acyclic Stereocontrol in the Additions of Nucleophilic Alkenes to α-Chiral N-Sulfonyl Imines
Moore, Lucas C.,Lo, Anna,Fell, Jason S.,Duong, Matthew R.,Moreno, Jose A.,Rich, Barry E.,Bravo, Martin,Fettinger, James C.,Souza, Lucas W.,Olmstead, Marilyn M.,Houk, Kendall N.,Shaw, Jared T.
supporting information, p. 12214 - 12220 (2019/08/26)
Diastereoselective Lewis acid-mediated additions of nucleophilic alkenes to N-sulfonyl imines are reported. The canonical polar Felkin–Anh model describing additions to carbonyls does not adequately describe analogous additions to N-sulfonyl imines. Herei
Stereodivergence in the Ireland-Claisen Rearrangement of α-Alkoxy Esters
Podunavac, Ma?a,Lacharity, Jacob J.,Jones, Kerry E.,Zakarian, Armen
supporting information, p. 4867 - 4870 (2018/08/24)
A systematic investigation into the Ireland-Claisen rearrangement of α-alkoxy esters is reported. In all cases, the use of KN(SiMe3)2 in toluene gave rearrangement products corresponding to a Z-enolate intermediate with excellent diastereoselectivity, presumably because of chelation control. On the other hand, chelation-controlled enolate formation could be overcome for most substrates through the use of lithium diisopropylamide (LDA) in tetrahydrofuran (THF).
Additions of Organomagnesium Halides to α-Alkoxy Ketones: Revision of the Chelation-Control Model
Read, Jacquelyne A.,Yang, Yingying,Woerpel
supporting information, p. 3346 - 3349 (2017/07/13)
The chelation-control model explains the high diastereoselectivity obtained in additions of organometallic nucleophiles to α-alkoxy ketones but fails for reactions of allylmagnesium halides. Low diastereoselectivity in ethereal solvents results from no chelation-induced rate acceleration. Additions of allylmagnesium bromide to carbonyl compounds are diastereoselective using CH2Cl2 as the solvent even though rate acceleration is still absent. Stereoselectivity likely arises from the predominance of the chelated form in solution. Therefore, a revised chelation-control model is proposed.
Specific reactivity of 2,4,6-tri-tert-butylanilide anions and its application to benzylation reagent
Yamada, Tomoyuki,Tsukagoshi, Shiori,Kitagawa, Osamu
, p. 317 - 320 (2017/01/03)
The reaction of methyl iodide with an anilide anion prepared from 2,4,6-tri-tert-butylanilide and NaH in CH3CN gave N-methyl anilide (N-alkylation product) as a major product, while in the reaction of benzyl bromide with the anilide anion in DMF, O-benzyl imidate (O-alkylation product) was obtained with almost complete selectivity. The treatment of O-benzyl imidate with alcohols and carboxylic acids in the presence of trifluoromethane sulfonic acid gave benzyl ethers and benzyl esters, respectively.
