722-01-0Relevant articles and documents
A solvent-reagent selection guide for Steglich-type esterification of carboxylic acids
Jordan, Andrew,Sneddon, Helen F.,Sydenham, Jack,Whymark, Kyran D.
supporting information, p. 6405 - 6413 (2021/09/10)
The Steglich esterification is a widely employed method for the formation of esters under mild conditions. A number of issues regarding the sustainability of this transformation have been identified, chiefly the use of hazardous carbodiimide coupling reagents in conjunction with solvents with considerable issues such as dichloromethane (DCM) and N,N-dimethylformamide (DMF). To overcome these issues, we have developed a solvent-reagent selection guide for the formation of esters via Steglich-type reactions with the aim of providing safer, more sustainable conditions. Optimum reaction conditions have been identified after high-throughput screening of solvent-reagent combinations, namely the use of Mukaiyama's reagent (Muk) in conjunction with solvent dimethyl carbonate (DMC). The new reaction conditions were also exemplified through the synthesis of a small selection of building-block like molecules and includes the formation of t-butyl esters.
STRIGOLACTONE ANALOGS AND METHODS OF USING
-
Page/Page column 50; 51, (2021/06/04)
Disclosed herein are compounds of Formula I and methods for regulating plant growth and/or combating root parasitic plants. Formulations containing one or more disclosed compounds or salts thereof, and one or more excipients are disclosed. Methods for reg
Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
, p. 66 - 71 (2020/11/18)
The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
Ac2O-Mediated Dearylacetylative Dimerization of 2-Arylacetyl-1-naphthols: Synthesis of Naphtho[1,2-b]furan-3-ones
Chang, Meng-Yang,Chen, Kuan-Ting,Chen, Shin-Mei,Hsiao, Yu-Ting
, p. 3605 - 3616 (2020/03/23)
A novel and efficient route for the synthesis of 2-Aryl-2-naphthyl naphtho[1,2-b]furan-3-ones is described via NaH/Ac2O-mediated dearylacetylative dimerization of 2-Arylacetyl-1-naphthols in refluxing THF under open-flask conditions. A plausibl
Asymmetric Transfer Hydrogenation of o-Hydroxyphenyl Ketones: Utilizing Directing Effects That Optimize the Asymmetric Synthesis of Challenging Alcohols
Clarkson, Guy J.,Wills, Martin,Zheng, Ye
supporting information, (2020/05/05)
A systematic range of o-hydroxyphenyl ketones were reduced under asymmetric transfer hydrogenation conditions using the C3-tethered catalyst 2. Two directing effects, i.e., an o-hydroxyphenyl coupled to a bulky aromatic on the opposite side of the ketone substrate, combine in a matched manner to deliver reduction products with very high enantiomeric excess.
Synthesis of 7-hydroxy-6H-naphtho[2,3-c]coumarinviaa TsOH-mediated tandem reaction
Li, Chenyu,Liang, Yong,Ma, Zhishuang,Wang, Ding,Wang, Nana,Wang, Tao,Zhang, Zunting
supporting information, p. 10369 - 10372 (2020/09/16)
A concise and efficient method for the synthesis of 7-hydroxy-6H-naphtho[2,3-c]coumarin using available 1-(2-hydroxyphenyl)-2-phenylethanone and Meldrum's acid has been developed. This transformation involved a tandem aldol reaction/lactonization/Friedel-Crafts reaction to form a lactone ring and a benzene ring. It showed high atom economy with water and acetone as the byproducts. Mechanism studies demonstrated two roles of Meldrum's acid: (i) as the reagent for the tandem reaction, and (ii) as the catalyst for the Friedel-Crafts reaction. Moreover, the hydroxyl group of 7-hydroxy-6H-naphtho[2,3-c]coumarin was further functionalized efficiently by arylethynyl, aryl, and cyano groups to furnish D-π-A compounds with excellent fluorescence emissions (ΦF= 0.14-0.78).
Rhodium-Catalyzed Carbonylative Coupling of Alkyl Halides with Phenols under Low CO Pressure
Ai, Han-Jun,Li, Chong-Liang,Wang, Hai,Wu, Xiao-Feng
, p. 5147 - 5152 (2020/05/27)
A rhodium-catalyzed carbonylative transformation of alkyl halides under low pressure of CO has been developed. This robust catalyst system allows using phenols as the carbonylative coupling partner and, meanwhile, exhibits high functional group tolerance and good chemoselectivity. Substrates even with a large steric hindrance group or multiple reaction sites can be selectively converted into the desired products in good to excellent yields. A gram-scale experiment was performed and delivered an almost quantitative amount of the product. Control experiments were performed as well, and a possible reaction mechanism is proposed.
Base-free Enantioselective C(1)-Ammonium Enolate Catalysis Exploiting Aryloxides: A Synthetic and Mechanistic Study
McLaughlin, Calum,Slawin, Alexandra M. Z.,Smith, Andrew D.
supporting information, p. 15111 - 15119 (2019/11/05)
An isothiourea-catalyzed enantioselective Michael addition of aryl ester pronucleophiles to vinyl bis-sulfones via C(1)-ammonium enolate intermediates has been developed. This operationally simple method allows the base-free functionalization of aryl esters to form α-functionalized products containing two contiguous tertiary stereogenic centres in excellent yield and stereoselectivity (all ≥99:1 er). Key to the success of this methodology is the multifunctional role of the aryloxide, which operates as a leaving group, Br?nsted base, Br?nsted acid and Lewis base within the catalytic cycle. Comprehensive mechanistic studies, including variable time normalization analysis (VTNA) and isotopologue competition experiments, have been carried out. These studies have identified (i) orders of all reactants; (ii) a turnover-limiting Michael addition step, (iii) product inhibition, (iv) the catalyst resting state and (v) catalyst deactivation through protonation.
Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition-lactonisations
Young, Claire M.,Taylor, James E.,Smith, Andrew D.
supporting information, p. 4747 - 4752 (2019/05/24)
An evaluation of a range of aryl, alkyl and vinyl esters as prospective C(1)-ammonium enolate precursors in enantioselective Michael addition-lactonisation processes with (E)-trifluoromethylenones using isothiourea catalysis is reported. Electron deficient aryl esters are required for reactivity, with 2,4,6-trichlorophenyl esters providing optimal product yields. Catalyst screening showed that tetramisole was the most effective isothiourea catalyst, giving the desired dihydropyranone product in excellent yield and stereoselectivity (up to 90 : 10 dr and 98 : 2 er). The scope and limitations of this process have been evaluated, with a range of diester products being generated after ring-opening with MeOH to give stereodefined dihydropyranones with excellent stereocontrol (10 examples, typically ～90 : 10 dr and >95 : 5 er).
Direct C-C Bond Formation from Alkanes Using Ni-Photoredox Catalysis
Ackerman, Laura K. G.,Martinez Alvarado, Jesus I.,Doyle, Abigail G.
, p. 14059 - 14063 (2018/10/24)
A method for direct cross coupling between unactivated C(sp3)-H bonds and chloroformates has been accomplished via nickel and photoredox catalysis. A diverse range of feedstock chemicals, such as (a)cyclic alkanes and toluenes, along with late-stage intermediates, undergo intermolecular C-C bond formation to afford esters under mild conditions using only 3 equiv of the C-H partner. Site selectivity is predictable according to bond strength and polarity trends that are consistent with the intermediacy of a chlorine radical as the hydrogen atom-abstracting species.
