42599-16-6Relevant articles and documents
A relay catalysis strategy for enantioselective nickel-catalyzed migratory hydroarylation forming chiral α-aryl alkylboronates
Chen, Jian,Liang, Yong,Ma, Jiawei,Meng, Lingpu,Zhang, Yao,Zhu, Shaolin
, p. 3171 - 3188 (2021/11/16)
Ligand-controlled reactivity plays an important role in transition-metal catalysis, enabling a vast number of efficient transformations to be discovered and developed. However, a single ligand is generally used to promote all steps of the catalytic cycle (e.g., oxidative addition, reductive elimination), a requirement that makes ligand design challenging and limits its generality, especially in relay asymmetric transformations. We hypothesized that multiple ligands with a metal center might be used to sequentially promote multiple catalytic steps, thereby combining complementary catalytic reactivities through a simple combination of simple ligands. With this relay catalysis strategy (L/L?), we report here the first highly regio- and enantioselective remote hydroarylation process. By synergistic combination of a known chain-walking ligand and a simple asymmetric cross-coupling ligand with the nickel catalyst, enantioenriched α-aryl alkylboronates could be rapidly obtained as versatile synthetic intermediates through this formal asymmetric remote C(sp3)-H arylation process.
A Tunable Route to Prepare α,β-Unsaturated Esters and α,β-Unsaturated-γ-Keto Esters through Copper-Catalyzed Coupling of Alkenyl Boronic Acids with Phosphorus Ylides
Bi, Hong-Yan,Liu, Feng-Ping,Liang, Cui,Su, Gui-Fa,Mo, Dong-Liang
supporting information, p. 1510 - 1516 (2018/03/05)
A tunable strategy to prepare α,β-unsaturated esters and α,β-unsaturated-γ-keto esters in good to excellent yields was developed through copper-catalyzed oxidative coupling of phosphorus ylides with alkenyl boronic acids under mild conditions. The reaction without water afforded α,β-unsaturated esters, ketones, and amides while α,β-unsaturated-γ-keto esters, 1,4-α,β-unsaturated diketones and α,β-unsaturated-γ-keto amides were obtained when using 5.0 equiv. of water. H2O18 labeling experiments showed that water played an important role in the formation of α,β-unsaturated-γ-keto esters. A plausible formation mechanism for α,β-unsaturated esters and α,β-unsaturated-γ-keto esters was proposed based on mechanistic studies. Phosphonium salts could also be used directly as coupling partners instead of phosphorus ylides. The reaction exhibited a broad substrate scope, good functional group tolerance, good regioselectivity, and diverse coupling products. (Figure presented.).
2-Pyrones possessing antimicrobial and cytotoxic activities
Fairlamb, Ian J. S.,Marrison, Lester R.,Dickinson, Julia M.,Lu, Feng-Ju,Schmidt, Jan Peter
, p. 4285 - 4299 (2007/10/03)
The 2-pyrone sub-unit is found in a number of natural products possessing broad spectrum biological activity. Such compounds are validated as being capable of binding to specific protein domains and able to exert a remarkable range of biological effects. In an effort to identify synthetic 2-pyrones with interesting biological effects, herein we report the synthesis and biological evaluation of 4-substituted-6-methyl-2-pyrones. Synthetic routes to 4-alkyl/alkenyl/aryl/alkynyl-6-methyl-2-pyrones have been developed utilising Sonogashira, Suzuki and Negishi cross-coupling starting from readily available 4-bromo-6-methyl-2-pyrone. Specific conditions for each organometallic protocol were required for successful cross-coupling. In particular, a triethylamine/acetonitrile - base/solvent mixture was crucial to Sonogashira alkynylation of 4-bromo-6-methyl-2-pyrone, whereas thallium carbonate was a mandatory base for the Suzuki cross-coupling of trialkylboranes. The 2-pyrones demonstrate potent inhibitory activity against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Schizosaccharomyces pombe and Botrytis cinerea. The growth inhibitory activities of selected 2-pyrones were determined in A2780 human ovarian carcinoma and K562 human chronic myelogenous leukaemia cell lines using an in vitro cell culture system (MTT assay). These studies demonstrate that 4-phenylethynyl-, 4-tetrahydropyranylpropargyl ether- and 4-ethynyl-6-methyl-2-pyrones have excellent potential as a new class of anticancer agents.
