cas 4136-21-4, 2-HYDROXY-1-(4-METHOXYPHENYL)-1-ETHANONE

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Chiral Bidentate Phosphoramidite-Pd Catalyzed Asymmetric Decarboxylative Dipolar Cycloaddition for Multistereogenic Tetrahydrofurans with Cyclic N-Sulfonyl Ketimine Moieties
An asymmetric [3 + 2] cycloaddition of vinyl ethylenecarbonates (VECs) and (E)-3-arylvinyl substituted benzo[d] isothiazole 1,1-dioxides has been developed using the Pd complex of a bidentate phosphoramidite (Me-BIPAM) as the catalyst, providing a wide variety of chiral multistereogenic vinyltetrahydrofurans in good yields with excellent diastereo- and enantioselectivities (up to >20:1 dr, 99% ee).
Lv, Hao-Peng,Yang, Xiao-Peng,Wang, Bai-Lin,Yang, Hao-Di,Wang, Xing-Wang,Wang, Zheng
supporting information
p. 4715 - 4720
(2021/06/28)

Palladium-Catalyzed (3+3) Annulation of Allenylethylene Carbonates with Nitrile Oxides
In this paper, we designed and synthesized a new type of cyclic carbonates, allenylethylene carbonates (AECs). With AECs as reactive precursors, we developed palladium-catalyzed (3+3) annulation of AECs with nitrile oxides. Various AECs worked well in this reaction under mild reaction conditions. A variety of 5,6-dihydro-1,4,2-dioxazine derivatives with allenyl quaternary stereocenters can be accessed in a facile manner in high yields (≤98%).
Pan, Ting,Gao, Xing,Yang, Sen,Wang, Lan,Hu, Yimin,Liu, Min,Wang, Wei,Wu, Yongjun,Zheng, Bing,Guo, Hongchao
supporting information
p. 5750 - 5754
(2021/08/16)

One-Pot Enzymatic-Chemical Cascade Route for Synthesizing Aromatic α-Hydroxy Ketones
2-Hydroxyacetophenone (2-HAP) is an important building block for the production of a series of natural products and pharmaceuticals; however, there is no safe, efficient, and economical method for 2-HAP synthesis. Here, a one-pot enzymatic-chemical cascade route was designed for synthesizing 2-HAP based on retrosynthetic analysis. First, a spontaneous proton-transfer reaction was designed using a computational simulation that enabled 2-HAP synthesis from the isomer 2-hydroxy-2-phenylacetaldehyde. A route for 2-hydroxy-2-phenylacetaldehyde synthesis was then constructed by introducing the unnatural substrate glyoxylic acid into a C-C ligation reaction catalyzed by Candida tropicalis pyruvate decarboxylase. Assembly and optimization of this enzymatic-chemical cascade route resulted in a final yield of 92.7%. Furthermore, stereospecific carbonyl reductases were introduced to construct a synthetic application platform that enabled further transformation of 2-HAP into (S)- and (R)-1-phenyl-1,2-ethanediol. This method of cascading spontaneous chemical and enzymatic reactions to synthesize chemicals offers insight into avenues for synthesizing other valuable chemicals.
Wang, Lei,Song, Wei,Wang, Binju,Zhang, Yan,Xu, Xin,Wu, Jing,Gao, Cong,Liu, Jia,Chen, Xiulai,Chen, Jinghua,Liu, Liming
p. 2808 - 2818
(2021/03/15)

Pd-Catalyzed Decarboxylative Olefination: Stereoselective Synthesis of Polysubstituted Butadienes and Macrocyclic P-glycoprotein Inhibitors
The efficient and stereoselective synthesis of polysubstituted butadienes, especially the multifunctional butadienes, represents a great challenge in organic synthesis. Herein, we wish to report a distinctive Pd(0) carbene-initiated decarboxylative olefination approach that enables the direct coupling of diazo esters with vinylethylene carbonates (VECs), vinyl oxazolidinones, or vinyl benzoxazinones to afford alcohol-, amine-, or aniline-containing 1,3-dienes in moderate to high yields and with excellent stereoselectivity. This protocol features operational simplicity, mild reaction conditions, a broad substrate scope, and gram-scalability. Notably, a structurally unique allylic Pd(II) intermediate was isolated and characterized. DFT calculation and control experiments demonstrated that a rare Pd(0) carbene intermediate could be involved in this reaction. Moreover, the polysubstituted butadienes as novel building blocks were unprecedentedly assembled into macrocycles, which efficiently inhibited the P-glycoprotein and dramatically reversed multidrug resistance in cancer cells by 190-fold.
Chen, Xiangyang,Hao, Jiping,Houk, K. N.,Li, Yingzi,Lou, Liguang,Quan, Haitian,Song, Bichao,Wang, Lu,Xia, Yuanzhi,Xie, Peipei,Xu, Zhongliang,Yang, Weibo
supporting information
p. 9982 - 9992
(2020/06/27)

Palladium-Catalyzed [5 + 2] Annulation of Vinylethylene Carbonates with Barbiturate-Derived Alkenes
A palladium/XantPhos-catalyzed [5 + 2] annulation of VECs with electron-deficient alkenes having an isolated carbon-carbon double bond has been developed to afford spirobarbiturate-tetrahydrooxepines. This study provides an expedient assembly of biologically interesting spirobarbiturate-tetrahydrooxepines. The easy scalability and versatile transformability of the reaction products were also exhibited.
Chen, Yuehua,Deng, Hao,Gao, Xing,Guo, Hongchao,Jiang, Feng,Wang, Wei,Wu, Yongjun,Zhu, Dongyu
supporting information
p. 7158 - 7163
(2020/10/02)

Synthesis of pentafluorobenzene-based NHC adducts and their catalytic activity in the microwave-assisted reactions of aldehydes
N-Heterocyclic carbenes (NHCs) have been widely used in organometallic chemistry as ligands, as well as standalone organocatalysts in various reactions, mostly using aromatic aldehydes as substrates. We have previously demonstrated the efficiency of azolium-2-carboxylate zwitterions in the hydroxymethylation of aldehydes, especially aliphatic aldehydes, under microwave irradiation. In the present work, we report a series of pentafluorobenzene-based NHC adducts and their efficiency in the hydroxymethylation and self-condensation of aliphatic and aromatic aldehydes using microwave irradiation. The free carbenes are released under the reaction conditions and 1,3-dimesityl-2-(perfluorophenyl)imidazolidine and 1,3-bis(2,6-dimethylphenyl)-2-(perfluorophenyl)imidazolidine proved to be the most potent precatalysts.
Papadaki, Evanthia,Magrioti, Victoria
supporting information

(2019/12/24)

Photocatalytic Cleavage of Aryl Ether in Modified Lignin to Non-phenolic Aromatics
Depolymerization of lignin meets the difficulty in cleaving the robust aryl ether bond. Herein, through installing an internal nucleophile in the β-O-4′ linkage, the selective cleavage of aryl ether was realized by the intramolecular substitution on aryl rings affording non-phenolic arylamine products. In particular, nitrogen-modified lignin models and lignin samples were employed to generate the iminyl radical under photocatalytic reduction, which acted as the internal nucleophile inducing aryl migration from O to the N atom. The following hydrolysis released primary arylamines and α-hydroxy ketones. Mechanism studies including electron spin resonance (ESR), fluorescence quenching experiments, and density functional theory (DFT) calculations proved the aryl migration pathway. This method enables access to non-phenolic arylamine products from lignin conversion.
Li, Hongji,Bunrit, Anon,Lu, Jianmin,Gao, Zhuyan,Luo, Nengchao,Liu, Huifang,Wang, Feng
p. 8843 - 8851
(2019/09/30)

Cleavage of lignin model compounds and ligninox using aqueous oxalic acid
Aqueous oxalic acid cleaves oxidised β-O-4 lignin model compounds by two distinct mechanisms that are dependent on the presence of the hydroxymethyl substituent. Various β-O-4 phenoxyacetophenones that do not contain the hydroxymethyl substituent undergo oxidative cleavage upon exposure to aqueous oxalic acid in the presence of air, likely through concerted ring opening of a dioxetane intermediate to give the corresponding benzoic acid and phenyl formate. Importantly, detrimental side reactions arising from singlet oxygen and hydroperoxy radicals (from both O2 and oxalic acid) are minimal when the cleavage is run under air compared to neat oxygen. When oxidised β-O-4 lignin model compounds bearing the hydroxymethyl group are cleaved by aqueous oxalic acid, the resulting diketone and phenol products arise from a redox neutral cleavage that is analogous to the formic acid-sodium formate mediated lignin cleavage process reported by Stahl. Aqueous oxalic acid also cleaves lignin itself, with oxidised milled wood lignin (MWLox) from Pinus radiata giving a 14% yield of ethyl acetate soluble aromatics with good selectivity for vanillin. Aqueous oxalic acid appears to be a promising lignin cleavage system given the benign, bio-based reagents, absence of metals and organic solvents and a simple extraction procedure that enables oxalic acid recycling.
Lindsay, Ashley C.,Kudo, Shinji,Sperry, Jonathan
supporting information
p. 7408 - 7415
(2019/08/15)

Vinylethylene Carbonates as α,β-Unsaturated Aldehyde Surrogates for Regioselective [3 + 3] Cycloaddition
Herein, we report a novel stepwise addition-controlled ring size method, to access tetrahydropyrimidines through an operationally simple [3 + 3] cycloaddition of vinylethylene carbonates with triazinanes. Interestingly, we could also use this method for a [3 + 3] oxidative cycloaddition, which allows the facile synthesis of polysubstituted terphenyls under mild conditions. Mechanistic studies suggest that vinylethylene carbonates could generate α,β-unsaturated aldehydes as 3-carbon synthons for cycloaddition via a combination process of Pd-catalyzed decarboxylation and β-H elimination.
Xu, Yi,Chen, Lu,Yang, Yu-Wen,Zhang, Zhiqiang,Yang, Weibo
supporting information
p. 6674 - 6678
(2019/09/03)

Formal Synthesis of Indolizidine and Quinolizidine Alkaloids from Vinyl Cyclic Carbonates
Cyclic carbonates have long been considered relatively inert molecules acting as protecting groups in complex multistep synthetic routes. This study shows that a concise, yet modular synthesis of indolizidine and quinolizidine alkaloids can be developed from vinyl-substituted cyclic carbonate (VCC) intermediates. Through a highly stereoselective palladium-catalyzed allylic alkylation reaction, these alkaloid motifs can be assembled in four synthetic and only two column purification steps. The combined results help to further advance functionalized cyclic carbonates as useful and reactive intermediates in natural product synthesis.
Cristòfol, àlex,B?hmer, Christian,Kleij, Arjan W.
supporting information
p. 15055 - 15058
(2019/11/16)

Fast-Synthesis of α-Phosphonyloxy Ketones as Drug Scaffolds in a Capillary Microreactor
A simple, room temperature approach for the fast single-step synthesis of α-phosphonyloxy ketone, a drug scaffold, has been developed which involves highly reactive species i.e., 1,2-dicarbonyls that readily react with trialkyl phosphites and formic acids in batch as well as in continuous-flow with the flow rate of 3 ml/min (tR = ～4 s). The present approach reduced the synthesis time from hours to minutes in batch, which was further lowered to a few seconds precisely controlled by single capillary microfluidics. A wide range of 1,2-dicarbonyl derivatives were smoothly transformed to their corresponding α-phosphonyloxy ketones in moderate to good yields (50–82 %) under optimized flow-reaction conditions. Further, the α-phosphonyloxy ketones produced can be utilized in batch process to form benzoin, oxazole core, and α,α′-diarylated carbonyl compounds in 82 %, 50 %, and 54 % yields, respectively, which are alternative key precursors/scaffolds of natural products and active pharmaceutical ingredients (APIs).
Ramanjaneyulu, Bandaru T.,Vidyacharan, Shinde,Yim, Se Jun,Kim, Dong-Pyo
supporting information
p. 7730 - 7734
(2019/12/24)

Regioselective three-component synthesis of 1,2-diarylindoles from cyclohexanones, α-hydroxyketones and anilines under transition-metal-free conditions
A facile method for the one-pot synthesis of 1,2-diarylindoles under transition-metal-free conditions is described. Cyclohexanones were used as the aryl sources via the dehydrogenative aromatization process. One C-C and two C-N bonds were selectively formed via a domino reaction. This protocol provides a convenient approach for the construction of valuable bioactive 1,2-diarylindoles from readily available cyclohexanones, α-hydroxyketones and anilines.
Li, Cheng,Xie, Yanjun,Xiao, Fuhong,Huang, Huawen,Deng, Guo-Jun
supporting information
p. 4079 - 4082
(2019/04/25)

Spiro[indene-1,4′-oxa-zolidinones] Synthesis via Rh(III)-Catalyzed Coupling of 4-Phenyl-1,3-oxazol-2(3 H)-ones with Alkynes: A Redox-Neutral Approach
Transition-metal-catalyzed C-H activation synthesis of heterocyclic spiro[4,4]nonanes has persistently witnessed the use of additional stoichiometric transition-metal oxidant when employing C=C bond as the spiro ring closure site. Herein, we have addressed the issue by reporting a redox-neutral strategy for spiro[indene-1,4′-oxa-zolidinones] synthesis via Rh(III)-catalyzed coupling of 4-phenyl-1,3-oxazol-2(3H)-ones with alkynes. The synthesis features a broad substrate scope and high regiospecificity.
Liu, Zhongsu,Zhang, Wenjing,Guo, Shan,Zhu, Jin
p. 11945 - 11957
(2019/10/02)

NON-IONIC LOW DIFFUSING PHOTO-ACID GENERATORS
Non-ionic photo-acid generating (PAG) compounds were prepared that contain an aryl ketone group. The disclosed non-polymeric PAGs release a strong sulfonic acid when exposed to high energy radiation such as deep UV or extreme UV light. The photo-generated sulfonic acid has a low diffusion rate in an exposed resist layer subjected to a post-exposure bake (PEB) at 100° C. to 150° C., resulting in formation of good line patterns after development. At higher temperatures, the PAGs undergo a thermal reaction to form a sulfonic acid.
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Paragraph 0167; 0168

(2018/03/09)

Chiral Ion-Pair Organocatalyst-Promoted Efficient Enantio-selective Reduction of α-Hydroxy Ketones
The enantioselective reduction of α-hydroxy ketones with catecholborane has been developed employing 5 mol% of an 1,1′-bi-2-naphthol (BINOL)-derived ion-pair organocatalyst. This methodology provides a straightforward access to the corresponding aromatic 1,2-diols in high yields (up to 90%) with excellent enantioselectivities (up to 97%). Furthermore, the α-amino ketones also could be reduced with moderate ee values under mild reaction condition. (Figure presented.).
Zhang, Yiliang,He, Li,Shi, Lei
supporting information
p. 1926 - 1931
(2018/03/27)

Divergent synthesis of N-heterocycles by Pd-catalyzed controllable cyclization of vinylethylene carbonates
Here, we report a palladium-catalyzed controllable cyclization of vinyl ethylene carbonates that proceeds through formal migration [2+3] and [5+2] cycloadditions, respectively, under mild conditions. The transformation described here affords a series of synthetically versatile 5,7-membered N-heterocycles which are found in natural products and pharmaceuticals with biological and medicinal properties.
Yang, Yuwen,Yang, Weibo
supporting information
p. 12182 - 12185
(2018/11/21)

Distal Functional Group Migration for Visible-light Induced Carbo-difluoroalkylation/monofluoroalkylation of Unactivated Alkenes
A general and practical protocol for elusive carbo-difluoroalkylation/ monofluoroalkylation of unactivated alkenes based on the distal functional group migration is described. A portfolio of functional groups including heteroaryl, imino, formyl, and alkynyl groups showcase the migratory aptitude. In combination with visible-light photocatalysis, a broad range of di- and mono-fluorinated alkyl ketones are readily obtained in synthetically useful yields under mild reaction conditions. (Figure presented.).
Yu, Jiajia,Wang, Dongping,Xu, Yan,Wu, Zhen,Zhu, Chen
supporting information
p. 744 - 750
(2017/12/26)

Enantioselective Silver-Catalyzed Cascade Synthesis of Fused Lactone and Lactam Oxazolines
A new and highly stereoselective cascade reaction between isocyanoacetate esters and α-hydroxy and α-amino ketones has been developed. A cinchona alkaloid derived aminophosphine/silver(I) catalyst complex promoted the reaction and enabled the ready synthesis of fused bicyclic γ-lactone and γ-lactam oxazolines with high enantiocontrol (up to 99% ee).
De La Campa, Raquel,Manzano, Rubén,Calleja, Paul,Ellis, Sam R.,Dixon, Darren J.
supporting information
p. 6033 - 6036
(2018/09/27)

Direct Aerobic Oxidative Reactions of 2-Hydroxyacetophenones
Valuable and direct aerobic oxidation reactions of 2-hydroxyacetophenones were explored. The concept was based on the in situ treatment of small quantities of aerobically formed α-keto aldehydes that drove the reactions to the corresponding products. This new strategy was applied for a variety of oxidative reactions of 2-hydroxyacetophenones, and valuable products such as phthalides, quinoxalines, and α-keto amides were obtained in good to high yields.
Sahoo, Subas Chandra,Nath, Utpal,Pan, Subhas Chandra
supporting information
p. 4434 - 4438
(2017/08/23)

Dual Role of H2O2 in Palladium-Catalyzed Dioxygenation of Terminal Alkenes
A palladium-catalyzed, environmentally friendly dioxygenation reaction of simple alkenes has been developed that enabled rapid assembly of valuable α-hydroxy ketones with high atom economy. Notably, control experiments and 18O isotope-labeling experiments established that H2O2 played a dominant dual role in this transformation.
Huang, Jiuzhong,Li, Jianxiao,Zheng, Jia,Wu, Wanqing,Hu, Weigao,Ouyang, Lu,Jiang, Huanfeng
supporting information
p. 3354 - 3357
(2017/07/13)

Microwave-assisted synthesis of hydroxymethyl ketones using azolium-2-carboxylate zwitterions as catalyst precursors
Following an initial screening of six common imidazolium, imidazolinium, and dithiolium salts in the presence of a base, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IDip) and 1,3-dimesitylimidazolin-2-ylidene (SIMes) were identified as promising organocatalysts for the microwave-assisted synthesis of hydroxymethyl ketones from aldehydes and paraformaldehyde. The azolium-2-carboxylate zwitterions IDip·CO2 and SIMes·CO2 were then tested as single-component N-heterocyclic carbene (NHC) precursors in the hydroxymethylation of heptanal and benzaldehyde. The latter adduct was an efficient precatalyst for the two reactions. It was successfully applied to a broad range of aliphatic and aromatic substrates (14 examples, 10–97% yields).
Papadaki, Evanthia,Delaude, Lionel,Magrioti, Victoria
p. 7295 - 7300
(2017/11/28)

Selective Debromination and α-Hydroxylation of α-Bromo Ketones Using Hantzsch Esters as Photoreductants
Two transformations initiated by photoinduced one-electron transfer to α-bromo ketones have been demonstrated. Hantzsch esters donate one electron to α-bromo ketones under photoirradiation, promoting reductive debromination. Subsequent reactions of the resulting radical species of the ketones with molecular oxygen and Hantzsch esters lead to α-hydroxylation or debromination, respectively. The relative dominance of the two pathways depends profoundly on the reaction conditions, including solvent, O2 levels, and the concentration of the Hantzsch esters. The synthetic protocols feature advantages because they require the environmentally benign sources, molecular oxygen and visible light.
Jung, Jaehun,Kim, Jun,Park, Gyurim,You, Youngmin,Cho, Eun Jin
supporting information
p. 74 - 80
(2016/01/25)

Chemoselective oxidant-free dehydrogenation of alcohols in lignin using Cp?Ir catalysts
A remarkably effective method of chemoselective dehydrogenation of alcohols in lignin has been developed with an iridium catalyst. An additional operation of Zn/NH4Cl via a two-step one pot process could further promote the cleavage of the C-O bond in β-O-4 units in lignin. And this reaction system was also applicable to native lignin as the molecular weight of native lignin decreased obviously as detected by gel permeation chromatography (GPC). Additionally, this is the first to date generation of the by-product H2 from native lignin and the by-product was straightforwardly captured by 1-decene. A probable mechanistic pathway was also proposed with the help of density functional theory (DFT) calculations.
Zhu, Rui,Wang, Bing,Cui, Minshu,Deng, Jin,Li, Xinglong,Ma, Yingbo,Fu, Yao
supporting information
p. 2029 - 2036
(2016/04/19)

An Ir/Zn Dual Catalysis for Enantio- and Diastereodivergent α-Allylation of α-Hydroxyketones
An Ir/Zn dual catalysis has been developed for the enantio- and diastereodivergent α-allylation of unprotected α-hydroxyketones under mild conditions, in the absence of any additional base. The cooperative action of a chiral iridium complex derived from phosphoramidites and a chiral Zn-ProPhenol complex is most likely responsible for its high reactivity, excellent enantioselectivity (up to >99% ee), and good diastereoselectivity (up to >20:1 dr). All four product stereoisomers could be prepared from the same set of starting materials and under identical conditions by simple selection of appropriate catalyst combinations.
Huo, Xiaohong,He, Rui,Zhang, Xiao,Zhang, Wanbin
supporting information
p. 11093 - 11096
(2016/10/12)

Investigation and Application of Amphoteric α-Amino Aldehyde: An in Situ Generated Species Based on Heyns Rearrangement
In situ generation of the reactive amphoteric α-amino aldehyde with simple α-hydroxy ketones and phenylamine via Heyns rearrangement was proven to be feasible. Metal-free domino reactions based on this reactive intermediate were effectively used to afford important N-heterocycles including polysubstituted pyrroles, indoles, and quinoxalines conveniently. A simple starting material, water as the only byproduct, and diversity of the useful products will make this method greatly attractive for pharmaceutics.
Li, Guangxun,Tang, Ling,Liu, Hongxin,Wang, Yingwei,Zhao, Gang,Tang, Zhuo
supporting information
p. 4526 - 4529
(2016/09/28)

Efficient microwave-assisted synthesis of hydroxymethyl ketones using NHC organocatalysts
Hydroxymethyl ketones are useful auxiliaries in organic synthesis and are also found in several medicinal agents. N-Heterocyclic carbenes (NHCs) have been used in the literature in order to introduce the hydroxymethyl group into aromatic aldehydes in good yields, but they are not that successful for aliphatic aldehydes. In the present work, the use of microwave irradiation has been efficiently incorporated into this organocatalytic synthesis of aromatic, but more importantly of aliphatic hydroxymethyl ketones that can be used as precursors for medicinally interesting compounds.
Nikolaou, Aikaterini,Kokotos, George,Magrioti, Victoria
p. 7628 - 7632
(2016/11/11)

Valine amide carbamate derivative containing propargyloxy group and application thereof
The invention relates to a valine amide carbamate derivative containing a propargyloxy group and a pharmaceutically acceptable salt thereof, belonging to the field of botanical bactericides. The valine amide carbamate derivative has a general formula (I) as shown in the specification, and the substituent R in the general formula (I) is as defined in the specification. The invention also relates to a preparation method for the compound as shown in the general formula (I), an intermediate specially prepared for development of the compound and application of the compound to prevention and treatment of plant diseases.
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(2017/08/25)

Tetrazolinone compound and application for same
Provided is a tetrazolinone compound given by formula (1) (wherein E represents a 5-membered aromatic hetero group, such as the pyrazolyl group, the thiazolyl group, or the imidazolyl group; R4 and R5 represent hydrogen atoms or the like; R6 represents a C1-12 alkyl group; R7, R8, and R9 represent hydrogen atoms or the like; R10 represents a C1-3 alkyl group, or a C1-3 haloalkyl group; Y represents an oxygen atom or the like; and Q represents an oxygen atom or the like), and having exceptional efficacy in controlling harmful organisms.
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Paragraph 0694; 0695; 0696; 0697; 0710; 0711; 0712; 0713

(2016/10/08)

Direct Synthesis of α-Alkoxy Ketones by Oxidative C–O Bond Formation
A convenient method to prepare α-alkoxy ketones has been developed by oxidative coupling of aryl methyl ketones and alcohols. With aqueous tert-butyl hydroperoxide (6.0 equiv.) as the oxidant, tetrabutylammonium iodide (20 mol-%) as the catalyst, and TsNHNH2(1.0 equiv.) as the additive, ketones underwent direct alkoxylation to give α-methoxy or α-ethoxy ketones in moderate to good yields.
Yu, Hui,Xu, Yilan,Fang, Yan,Dong, Rui
p. 5257 - 5262
(2016/11/13)

New synthetic strategy for chiral 2-oxazolidinones derivatives via rhodium-catalyzed asymmetric hydrogenation
Asymmetric hydrogenation of 4-substituted cyclic enamido esters catalyzed by a rhodium-TangPhos complex provides an efficient method for the synthesis of chiral 4-substituted oxazolinones with excellent yields and good enantioselectivities. The products are valuable chiral building blocks and the applications as chiral auxiliaries and pharmaceuticals are well-known.
Wang, Qingli,Tan, Xuefeng,Zhu, Ziyue,Dong, Xiu-Qin,Zhang, Xumu
supporting information
p. 658 - 662
(2016/01/26)

Green organocatalytic α-hydroxylation of ketones
An efficient and green method for the α-hydroxylation of substituted ketones has been developed. This method includes the in situ conversion of various ketones into the corresponding silyl enol ethers and their oxidation to the corresponding α-hydroxy ketones. Two protocols have been established leading either to protected α-hydroxy carbonyls or free α-hydroxy ketones. Both procedures are easy to follow and lead to good to high yields for a variety of ketones.
Voutyritsa, Errika,Theodorou, Alexis,Kokotos, Christoforos G.
p. 5708 - 5713
(2016/07/06)

Two-Step, Catalytic C-C Bond Oxidative Cleavage Process Converts Lignin Models and Extracts to Aromatic Acids
We herein report a two-step strategy for oxidative cleavage of lignin C-C bond to aromatic acids and phenols with molecular oxygen as oxidant. In the first step, lignin β-O-4 alcohol was oxidized to β-O-4 ketone over a VOSO4/TEMPO [(2,2,6,6-tetramethylpiperidin-1-yl)oxyl)] catalyst. In the second step, the C-C bond of β-O-4 linkages was selectively cleaved to acids and phenols by oxidation over a Cu/1,10-phenanthroline catalyst. Computational investigations suggested a copper-oxo-bridged dimer was the catalytically active site for hydrogen-abstraction from Cβ-H bond, which was the rate-determining step for the C-C bond cleavage.
Wang, Min,Lu, Jianmin,Zhang, Xiaochen,Li, Lihua,Li, Hongji,Luo, Nengchao,Wang, Feng
p. 6086 - 6090
(2016/09/09)

Photochemical and enzymatic SET promoted C-C bond cleavage reactions of lignin β-1 model compounds containing varying number of methoxy substituents on their arene rings
Abstract In the current study, 1,2-diarylpropan-1,3-diols, containing varying numbers of methoxy substituents that mimic β-1 type units in lignins, were prepared and subjected to photochemical and enzymatic SET oxidative C-C bond cleavage reactions to explore how product distributions and reactivity profiles depend on the numbers and positions of arene ring methoxy-substituents. For this purpose, product distributions of SET-promoted photochemical reactions of the β-1 model compounds and the characteristics of lignin peroxidase catalyzed bond cleavage reactions of these substances were explored. The results show that both the photochemical and enzymatic reactions, which are known to occur by initial SET to form arylpropanoid cation radicals, generate predominantly aldehydes and β-hydroxyketones through cation radical C1-C2 bond cleavage pathways. In addition, analysis of the relative quantum efficiencies of the SET photochemical processes shows that they do not depend greatly on the numbers and positions of arene ring methoxy substituents of the β-1 model compounds.
Lim, Suk Hyun,Lee, Woo Sol,Kim, Young-Il,Sohn, Youngku,Cho, Dae Won,Kim, Cheolhee,Kim, Eunae,Latham, John A.,Dunaway-Mariano, Debra,Mariano, Patrick S.
p. 4236 - 4247
(2015/06/02)

A new chiral C1-symmetric NHC-catalyzed addition to α-aryl substituted α,β-disubstituted enals: Enantioselective synthesis of fully functionalized dihydropyranones
The first enantioselective NHC-catalyzed activation of α-aryl substituted α,β-disubstituted unsaturated aldehyde is successfully developed via a highly-active acyl azolium intermediate. The new C1-symmetric biaryl-saturated imidazolium exhibits a superior ability to enable previously unavailable transformation, and the corresponding fully functionalized dihydropyranones are efficiently synthesized in high yields with excellent enantioselectivities. This journal is
Lu, Hong,Liu, Jin-Yu,Li, Chen-Guang,Lin, Jun-Bing,Liang, Yong-Min,Xu, Peng-Fei
supporting information
p. 4473 - 4476
(2015/03/18)

Synthesis and antibacterial activities of cadiolides A, B and C and analogues
The one-pot multicomponent synthesis of natural butenolides named cadiolides A, B, C and analogues has been realized. The antibacterial structure activity relationship shows that the presence of phenolic hydroxyl groups and the number and position of bromine atoms on the different aromatic rings are important features for antibacterial activity, besides it was demonstrated the tolerance of both benzene and furan ring at position 3 of the butenolide nucleus. Furthermore, none of the most relevant antibacterial compounds showed any cytotoxicity in freshly isolated human neutrophils.
Boulangé, Agathe,Parraga, Javier,Galán, Abraham,Cabedo, Nuria,Leleu, Stéphane,Sanz, Maria Jesus,Cortes, Diego,Franck, Xavier
p. 3618 - 3628
(2015/07/27)

Homogeneous catalytic oxidation of styrene and styrene derivatives with hydrogen peroxide in the presence of transition metal-substituted polyoxotungstates
The tetrabutylammonium (TBA) salts of the Keggin-type polyoxotungstates with general formula [XW11M(H2O)O39](n-m)-, where X = P, B or Si and M = Mn, Fe or Co, were evaluated as catalysts in the oxidation of styrene, α-methylstyrene, p-methylstyrene, α,p-dimethylstyrene, p-chlorostyrene, p-nitrostyrene, and p-methoxystyrene under mild conditions, using aqueous H2O2 as an eco-sustainable oxidant. In this study, the influence of the catalysts and of the different styrene substituents on the oxidation reaction profile was evaluated in terms of conversion and selectivity. For all the performed catalytic studies, the main product results from the oxidative cleavage of the vinyl double bond, except in the case of the oxidation of p-methoxystyrene catalysed by BW11Mn, for which p-methoxyphenol is the main product. The catalysts BW11Mn and SiW11Co give rise to 100% conversion for almost all of the substrates, excluding p-methoxystyrene and p-nitrostyrene for both catalysts and α,p-dimethylstyrene only in the case of BW11Mn. The selectivity for C=C cleavage products resulting from the oxidative cleavage of the vinyl double bond can be as high as 98%, reaching 98% conversion for p-nitrostyrene when SiW11Co was used as a catalyst. Possible pathways are discussed and the oxidation of a few presumed intermediates was carried out. The systematic study of several substituted styrene derivatives suggests a possible reactivity order for these compounds in the catalytic system considered.
Duarte, Tiago A. G.,Estrada, Ana C.,Simes, Mrio M. Q.,Santos, Isabel C. M. S.,Cavaleiro, Ana M. V.,Neves, M. Graca P. M. S.,Cavaleiro, Jos A. S.
p. 351 - 363
(2015/02/18)

Oxidative coupling of terminal alkyne with α-hydroxy ketone: An expedient approach toward ynediones
An efficient and mild copper-catalyzed one-pot approach toward ynediones has been established. A variety of ynediones were constructed directly through oxidative coupling of alkyne with α-hydroxy ketone. Oxygen-oxidizing and neutral conditions in one-pot for a wide range of substrates including natural product derivatives make this transformation highly efficient and practical. On the basis of control experiments, in situ IR measurements, and isotopic labeling experiments, a plausible mechanism involving intermediate phenylglyoxal was drawn. Applications by synthesis of various heterocycles were also investigated.
Zhang, Zeguang,Jiang, Xuefeng
supporting information
p. 4400 - 4403
(2015/02/18)

Regio- and enantio-selective oxidation of diols by Candida parapsilosis ATCC 7330
Selectivity between primary and secondary alcohols was observed in oxidation using whole cells of Candida parapsilosis ATCC 7330, where the secondary alcohol was preferentially oxidized. In racemic sec alcohols, the 'R' enantiomer was selectively oxidized to the corresponding keto alcohol (yield = 18-54%) leaving the 'S' diol (yield = 31-69% and enantiomeric excess from 14% to >99%). A biphasic system consisting of isooctane-water (48 : 2 v/v) was used as a medium for biotransformation at 25 °C. This is the first report of the regio- and enantio-selective oxidation of diols using C. parapsilosis ATCC 7330.
Sivakumari, Thakkellapati,Chadha, Anju
p. 60526 - 60533
(2015/02/19)

Solar photochemical oxidation of alcohols using catalytic hydroquinone and copper nanoparticles under oxygen: Oxidative cleavage of lignin models
Alcohols are converted into to their corresponding carbonyl compounds using catalytic amounts of 1,4-hydroquinone with a copper nanoparticle electron transfer mediator with oxygen as the terminal oxidant in acetone as solvent under visible light irradiation. These conditions employing biorenewable hydroquinone as reagent were developed from initial experiments using stoichiometric amounts of 1,4-benzoquinone as oxidant. A range of benzylic and aliphatic primary and secondary alcohols are oxidized, affording the corresponding aldehydes or ketones in moderate to excellent yields. The methodology is also applicable to the oxidative degradation of lignin model compounds that undergo C-C bond cleavage to give simple aromatic compounds.
Mitchell, Lorna J.,Moody, Christopher J.
p. 11091 - 11100
(2015/01/08)

Highly enantioselective deracemization of 1-phenyl-1,2-ethanediol and its derivatives by stereoinversion using Candida albicans in a one-pot process
A very simple methodology was developed to transform racemic 1-(4-substitutedphenyl)-1,2-ethanediols using resting cells of Candida albicans CCT 0776 through a one-pot two-step process in which the (R)-stereoisomer was completely oxidized to the corresponding substituted-α-hydroxyacetophenones, which were completely reduced to produce (S)-1-(4-substitutedphenyl)-1,2-ethanediols in good isolated yield (60-85%) and with high enantiomeric excess (99% ee). The overall process corresponded to an enantioselective deracemization by stereoinversion of the (R)-enantiomer. The process was not achieved for other similar 1,2-diols using the same reaction conditions, which indicates a structural restriction of substrates by the active pocket of the enzymes of C. albicans involved in the stereoinversion process.
Cazetta, Tarcila,Moran, Paulo J.S.,Rodrigues, J. Augusto R.
p. 178 - 183
(2014/12/11)

Flexible stereoselective functionalizations of ketones through umpolung with hypervalent iodine reagents
The functionalization of carbonyl compounds in the α-position has gathered much attention as a synthetic route because of the wide biological importance of such products. Through polarity reversal, or "umpolung", we show here that typical nucleophiles, such as oxygen, nitrogen, and even carbon nucleophiles, can be used for addition reactions after tethering them to enol ethers. Our findings allow novel retrosynthetic planning and rapid assembly of structures previously accessible only by multistep sequences. A Nu approach: An efficient α-functionalization of ketones with a range of simple and useful nucleophiles is possible by using hypervalent iodine reagents (see scheme; Nu′ can be the Nu itself or a protected form of this nucleophile group).
Mizar, Pushpak,Wirth, Thomas
supporting information
p. 5993 - 5997
(2014/06/10)

Experimental study on the reaction pathway of α-haloacetophenones with NaOMe: Examination of bifurcation mechanism
The reaction of PhCOCH2Br and NaOMe in MeOH gave PhCOCH 2OH as the major product and PhCOCH2OMe as the minor product. Substituent effects on the reactivity and product selectivity revealed that an electron-withdrawing substituent on the phenyl ring enhanced the overall reactivity and gave more alcohol than ether. It was indicated that the alcohol was formed via carbonyl addition-epoxidation, whereas the ether was formed by direct substitution. Substituent effects on the reaction rates, as well as the effects of NaOMe concentration on the rate and product ratio for both reactions of PhCOCH2Br and PhCOCH2CI are in line with the mechanism that the alcohol and ether products were formed via two independent and concurrent routes, carbonyl addition and a-carbon attack, respectively, and thus the reaction mechanism could be different from the bifurcation mechanism previously predicted for the reaction of PhCOCH2Br by a simulation study in the gas phase.
Tagawa, Kohei,Sasagawa, Keita,Wakisaka, Ken,Monjiyama, Shunsuke,Katayama, Mika,Yamataka, Hiroshi
p. 119 - 126
(2014/02/14)

A photochemical strategy for lignin degradation at room temperature
The development of a room-temperature lignin degradation strategy consisting of a chemoselective benzylic oxidation with a recyclable oxidant ([4-AcNH-TEMPO]BF4) and a catalytic reductive C-O bond cleavage utilizing the photocatalyst [Ir(ppy)2(dtbbpy)]PF6 is described. This system was tested on relevant lignin model substrates containing β-O-4 linkages to generate fragmentation products in good to excellent yields.
Nguyen, John D.,Matsuura, Bryan S.,Stephenson, Corey R. J.
p. 1218 - 1221
(2014/02/14)

Solar photochemical oxidations of benzylic and allylic alcohols using catalytic organo-oxidation with DDQ: Application to lignin models
Visible light has a dramatic effect on the oxidation of benzylic and allylic alcohols, including those deactivated by electron-withdrawing groups, and β-O-4 lignin models, using catalytic amounts of the organo-oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Sodium nitrite or tert-butyl nitrite is used as cocatalyst, and oxygen is employed as the terminal oxidant.
Walsh, Katie,Sneddon, Helen F.,Moody, Christopher J.
p. 5224 - 5227
(2014/12/11)

Versatile synthesis of acylfuranones by reaction of acylketenes with α-hydroxy ketones: Application to the one-step multicomponent synthesis of cadiolide B and its analogues
Functionalized acylfuranones have been prepared in a one-step procedure by thermal fragmentation of the corresponding dioxinones in the presence of hydroxy ketones in basic conditions. Multicomponent reactions also occur on addition of an aldehyde as a third reaction partner resulting in an expeditious access to cadiolide B and its analogues. A new method for the synthesis of acylfuranones is described based on the fragmentation of dioxinones to acylketenes followed by trapping with hydroxy ketones. Addition of an aldehyde as a third reaction partner leads to a supplementary aldolization/crotonization sequence resulting in an expeditious synthesis of cadiolide B and its analogues. Copyright
Peixoto, Philippe Alexandre,Boulange, Agathe,Leleu, Stephane,Franck, Xavier
p. 3316 - 3327
(2013/06/27)

Release of guests from encapsulated masked hydrophobic precursors by a phototrigger
Examples of release of organic acids from encapsulated p-methoxyphenacyl esters provided here demonstrate the value of a phototrigger strategy to release chemicals of interest in water from hydrophobic precursors. In this study, a photochemical β-cleavage process centered on the p-methoxyphenacyl group is exploited to release the acid of interest from a water-soluble capsule made up of octa acid.
Jayaraj, Nithyanandhan,Jagadesan, Pradeepkumar,Samanta, Shampa R.,Da Silva, Jose P.,Ramamurthy
p. 4374 - 4377
(2013/09/24)

Asymmetric syn-aldol reaction of α-hydroxy ketones with tertiary amine catalysts
The tertiary amine-catalyzed direct asymmetric aldol reaction of 2-hydroxyacetophenones (2-hydroxy-1-arylethanones) with a variety of aliphatic aldehydes has been demonstrated. By using 20 mol-% of unmodified cinchonine as catalyst, the direct aldol reaction products were isolated in good yields and with remarkably high syn diastereocontrol and good asymmetric induction (40-78 % ee). This newly elaborated tertiary-amine-catalyzed direct asymmetric aldol reaction has extended the scope of organocatalytic processes to aromatic α-hydroxy ketones, which have hitherto been unreactive towards enamine catalysis. Unmodified cinchona alkaloids have been found to promote efficiently the direct aldol reaction of hydroxy ketones and various aldehydes in good yields and with remarkably high syn diastereocontrol and good asymmetric induction (40-78 % ee). Copyright
Bas, Sebastian,Wozniak, Lukasz,Cygan, Judyta,Mlynarski, Jacek
p. 6917 - 6923
(2013/11/06)

Activity of 6-aryl-pyrrolo[2,3-d]pyrimidine-4-amines to Tetrahymena
A series 6-aryl-pyrrolo[2,3-d]pyrimidine-4-amines (43 compounds), some of which are epidermal growth factor tyrosine kinase inhibitors, were tested for their protozoal toxicity using an environmental Tetrahymena strain as model organism. The protozoacidal activity of the analogues was found to be highly dependent on a 4-hydroxyl group at the 6-aryl ring, and a chiral 1-phenylethanamine substituent in position 4. Further, the potency was affected by the aromatic substitution pattern of the phenylethanamine: the unsubstituted, the meta-fluoro and the para-bromo substituted derivatives had the lowest minimum protozoacidal concentrations (8-16 μg/mL). Surprisingly, both enantiomers were found to have high potency suggesting that this compound class could have several modes of action. No correlation was found between the compounds protozoacidal activity and the in vitro epidermal growth factor receptor tyrosine kinase inhibitory potency. This suggests that the observed antimicrobial effects are related to other targets. Testing towards a panel of kinases indicated several alternative modes of action.
Kaspersen, Svein Jacob,Hoff, Bard Helge,Sundby, Eirik,Charnock, Colin
p. 35 - 41,7
(2020/07/30)

Biocatalytic reduction of prochiral aromatic ketones to optically pure alcohols by a coupled enzyme system for cofactor regeneration
A simple, highly efficient, and economical biphasic cell-free system was developed for biocatalytic reduction of prochiral aromatic ketones to furnish enantiopure alcohols. This system is characterized by using endogenous enzymes of the cell-free extract to form enzyme-coupled NADPH recycling system. Besides, it offered much higher productivity than whole cells and greatly simplified the preparation process of biocatalysts in comparison with isolated enzymes. Various prochiral aromatic ketones, especially α-substituted acetophenone derivatives, were reduced to chiral alcohols with excellent enantiomeric excess (ee) and moderate to good yield by this cell-free system.
Yan, Zhen,Nie, Yao,Xu, Yan,Liu, Xiang,Xiao, Rong
p. 999 - 1002
(2011/03/21)

Direct and efficient N-heterocyclic carbene-catalyzed hydroxymethylation of aldehydes
The N-heterocyclic carbene-catalyzed coupling of several aldehydes with paraformaldehyde is reported, directly providing the corresponding valuable hydroxymethyl ketones. Results of first mechanistic experiments for this remarkably selective transformation are also provided.
Kuhl, Nadine,Glorius, Frank
supporting information; experimental part
p. 573 - 575
(2011/02/28)