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Search for "ketone" in Full Text gives 662 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

  • Inaiá O. Rocha,
  • Yuri G. Kappenberg,
  • Wilian C. Rosa,
  • Clarissa P. Frizzo,
  • Nilo Zanatta,
  • Marcos A. P. Martins,
  • Isadora Tisoco,
  • Bernardo A. Iglesias and
  • Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

Graphical Abstract
  • base; Introduction Schiff bases are an important class of organic compounds first reported by the German chemist Hugo Schiff in 1864 and are formed from the reversible condensation between a primary amine and an aldehyde or a ketone [1]. Also known as azomethines, aldimines, and more commonly as
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Published 01 Dec 2021

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

  • Dušan Đ. Škorić,
  • Olivera R. Klisurić,
  • Dimitar S. Jakimov,
  • Marija N. Sakač and
  • János J. Csanádi

Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174

Graphical Abstract
  • different ketone and enone precursors from cholic acid, deoxycholic acid, and chenodeoxycholic acid was established. Newly obtained tetrazole derivatives were characterized by NMR and X-ray diffraction spectroscopy. In a number of cases, preliminary antiproliferative tests of new compounds showed strong and
  • [21], this variation of the reaction draws considerably less attention in comparison to the usage in the synthesis of amides or lactams. As presented in Figure 2, after initial formation of the azidohydrine by addition of hydrazoic acid to the ketone, the reaction can undergo two pathways. In the
  • . Results and Discussion In order to investigate possibilities for the synthesis of bile acid B-ring- and bile acid C-ring-fused tetrazoles by a variation of the Schmidt reaction, the appropriate ketone and enone derivatives were prepared firstly. This was achieved using cholic acid, deoxycholic acid (1
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Published 20 Oct 2021

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

  • Pratibha Sharma,
  • Raakhi Gupta and
  • Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

Graphical Abstract
  • –91%) with excellent levels of stereocontrol (≈92% ee, >20:1 dr in all cases). The ketone group in the cascade product was reduced asymmetrically to a chiral secondary hydroxy group (Table 1) [26]. In this case, the role of Ph3CCO2H as additive is to furnish the conjugate base Ph3CO2− anion which
  • of carbamates, sulfonamides and acetamides 13 bearing an α,β-unsaturated ketone to synthesize a series of 2-substituted five- and six-membered heterocycles in good yields (up to 99%) and excellent enantioselectivity (92–97.5% ee) (Table 3). As in an earlier case [29], several acids were tested as co
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Published 18 Oct 2021

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

  • Scott Benz and
  • Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

Graphical Abstract
  • features the 1,2-shift of an alkyl or aryl group. In the process, the hydroxy group is converted to a carbonyl and the aldehyde/ketone or imine is converted to an alcohol or amine. Such α-ketol/α-iminol rearrangements are used in a wide variety of synthetic applications including asymmetric synthesis
  • use of aldehydes (R′ = H), which are usually less stable than their ketone counterparts; (2) ring expansion (Z, R = cyclic) or contraction (Z, R′ = cyclic) of strained cyclic α-ketols; (3) the use of α-dicarbonyl compounds (R′ = acyl, ester, amide, etc.), which lead to more stable β-dicarbonyl
  • -moderate yields but with ≥74% ee, while the α-amino ketone products 15 could be obtained in nearly quantitative yields and variable ee, from 53% to 98% [6]. A fifth example of an enantioselective α-ketol rearrangement provides a twist by demonstrating the ability to function on substrates protected as
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Published 15 Oct 2021

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

  • Robin Klintworth,
  • Garreth L. Morgans,
  • Stefania M. Scalzullo,
  • Charles B. de Koning,
  • Willem A. L. van Otterlo and
  • Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

Graphical Abstract
  • -trig interactions of both the enol nucleophile and the ketone in the transient intermediate 21 bring about formation of the new five-membered ring intermediate 22. Finally, acid-induced dehydration of 22 completes the formation of the pyrrole ring, resulting in conversion into the dihydropyrrolizine
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Published 13 Oct 2021

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

  • Andrey I. Puzanov,
  • Dmitry S. Ryabukhin,
  • Anna S. Zalivatskaya,
  • Dmitriy N. Zakusilo,
  • Darya S. Mikson,
  • Irina A. Boyarskaya and
  • Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

Graphical Abstract
  • ), oxadiazole 3a gave the product of hydration of the acetylene bond (4d, yield of 65%) existing in solution as equilibrium between ketone and enol forms in a ratio of 1.2:1 according to NMR data (see Supporting Information File 1). Then, reactions of 5-acetylenyl-1,2,4-oxadiazole 3a–d with arenes (benzene and
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Published 15 Sep 2021

Strategies for the synthesis of brevipolides

  • Yudhi D. Kurniawan and
  • A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

Graphical Abstract
  • acid (17) (Scheme 4). The β-hydroxy moiety in 44 can be installed via Sharpless dihydroxylation of the silyl enol ether derived from ketone 45. The 5,6-dihydro-α-pyrone group in ketone 45 is envisaged from protected diol 46 by the sequence of Mitsunobu esterification, ring-closing metathesis, and base
  • -promoted double bond migration. The cyclopropyl functionality in 46 can be assembled from the reaction of sulfur ylide and the α,β-unsaturated ketone 47, which in turn can be realized from the cross metathesis between commercially available ethyl vinyl ketone (48) and the C2-symmetrical diene-diol 49. The
  • afforded in 78% yield as an (E)-isomer exclusively after reaction with excess ethyl vinyl ketone (48) in the presence of a catalytic amount of Grubbs II catalyst and CuI. The free secondary alcohol in 51 required a protection prior to the next transformation. For this purpose, MEMCl was chosen instead of
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Published 14 Sep 2021

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

  • Sumana Mandal,
  • Raju D. Chaudhari and
  • Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

Graphical Abstract
  • enol ether derivative 79 forming carbocyclic compounds 81 with good yields via intermediate 80 [78]. The cyclization of compounds 79 undergo regioselective addition with the triple bond in exocyclic alkene position leading to the formation of α-mercury ketone 80, which were later functionalized by
  • ) [101]. Later it was shown that alkynyl diol 150 when treated with 20 mol % Hg(OTf)2 followed by Et3SiH afforded bispyranoyl ketone 151, but when Hg(OTf)2 was increased (1 equiv) then fused pyran-oxocane derivative 152 was isolated [102]. Six-membered morpholine derivatives were also synthesized by
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Published 09 Sep 2021

Phenolic constituents from twigs of Aleurites fordii and their biological activities

  • Kyoung Jin Park,
  • Won Se Suh,
  • Da Hye Yoon,
  • Chung Sub Kim,
  • Sun Yeou Kim and
  • Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

Graphical Abstract
  • ′)], and two methylenes [δH 3.23 (t, J = 6.0 Hz, 2H, H-8) and 3.96 (t, J = 6.0 Hz, 2H, H-9)]. The 13C NMR spectrum of compound 15 (Table 2) revealed 14 peaks for 17 carbons including a ketone carbon (δC 200.0), a 1,3,4,5-tetrasubstituted aromatic ring [δC 154.4 (×2), 140.7, 134.6, and 107.5 (×2)], two
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Published 07 Sep 2021

Photoredox catalysis in nickel-catalyzed C–H functionalization

  • Lusina Mantry,
  • Rajaram Maayuri,
  • Vikash Kumar and
  • Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

Graphical Abstract
  • desired product 23 and the active nickel(0) species 7-III. The triplet ketone sensitizers can also be employed in the HAT and SET processes [65]. Thus, Martin and co-workers presented an example of the arylation of α-oxy C(sp3)‒H bonds of ethers 9 with aryl bromides 3 employing synergy between the nickel
  • catalysis and ketone HAT photocatalyst [66]. Here, the catalytic system composed of the ketone photocatalyst (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone (24), Ni(acac)2, 5,5’-dimethyl-2,2’-bipyridine (5,5’-diMe-bpy), Na2CO3 under visible light (CFL) irradiation was found to be optimal to provide
  • similar reaction conditions with moderate to good yields. Based on their detailed mechanistic studies, the authors proposed a possible catalytic cycle involving a C–H cleavage via a HAT process between the triplet excited ketone photocatalyst 24 and the C(sp3)–H substrates (Figure 8) [66]. Thus, the
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Published 31 Aug 2021

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

  • Tülay Yıldız,
  • İrem Baştaş and
  • Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

Graphical Abstract
  • phenyl bromide to 2-phenoxybenzaldehyde. As a result, phenoxy secondary alcohol 2a containing three aromatic rings was obtained. In the third step, 2a was oxidized and the ketone derivative 3a was obtained in high yield. The oxidation reaction was carried out using PCC in DCM at room temperature. In the
  • fourth and final step, phenoxydiphenylalkene derivative 4a was prepared by a Wittig reaction, which was carried out using methyltriphenylphosphonium bromide with ketone 3a, in basic medium, at room temperature, and dry THF. After the structures of the starting compounds were elucidated, the method
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Published 30 Aug 2021

Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

  • Zhiwei Zhang,
  • Tao Zhou,
  • Taehui Yang,
  • Keisuke Fukaya,
  • Enjuro Harunari,
  • Shun Saito,
  • Katsuhisa Yamada,
  • Chiaki Imada,
  • Daisuke Urabe and
  • Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

Graphical Abstract
  • the dominant tautomers in solution. This is the first validation to state that the keto carbonyl unit in the five-membered ring (C24 in Figure 5) and the acyl ketone connecting at C2 (C3 in Figure 5) are preferably enolized to form stable isomeric structures in spirotetronic acids. The molecular
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Published 27 Aug 2021

Progress and challenges in the synthesis of sequence controlled polysaccharides

  • Giulio Fittolani,
  • Theodore Tyrikos-Ergas,
  • Denisa Vargová,
  • Manishkumar A. Chaube and
  • Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

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Published 05 Aug 2021

Asymmetric organocatalyzed synthesis of coumarin derivatives

  • Natália M. Moreira,
  • Lorena S. R. Martelli and
  • Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

Graphical Abstract
  • % ee) (Scheme 10). A catalytic asymmetric β-C−H functionalization of ketones 33 with 4-hydroxycoumarins 1 was developed by Zhu et al. [43]. The enamine, formed via reaction of the aminocatalyst 35 with the ketone, is oxidased by IBX resulting in the electrophilic imine, which in turn undergoes a
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Published 03 Aug 2021

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

  • Ryan M. Alam and
  • John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

Graphical Abstract
  • demonstrated a higher preference for N-1 indazole alkylation under conditions B, when compared with conditions A (Table 2, entries 1, 2, 4–7, and 9). Furthermore, C-3 ketone (22) and amide (23 and 24) substituted indazoles also gave the corresponding N-1 regioisomers with a high degree of N-1 regioselectivity
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Published 02 Aug 2021

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

  • Renato L. Carvalho,
  • Amanda S. de Miranda,
  • Mateus P. Nunes,
  • Roberto S. Gomes,
  • Guilherme A. M. Jardim and
  • Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Graphical Abstract
  • inspired by the biocatalytic action of the cytochrome P-450 cycle, which is driven by a reductase or bioreductant, and presented high versatility in incorporating both aldehyde and ketone functionalities into unprotected arylboronic acids. The reaction consists of using a porphyrin-based iron catalyst, and
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Published 30 Jul 2021

Development of N-F fluorinating agents and their fluorinations: Historical perspective

  • Teruo Umemoto,
  • Yuhao Yang and
  • Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

Graphical Abstract
  • carbanions [90]. The precursor 27-1, which was prepared in a three step protocol from saccharin, was fluorinated with FClO3 to give 27-2 in good yield (Scheme 60). Direct fluorination of 27-1 with 10% F2/N2 had failed because of decomposition. Various ketone enolates were successfully fluorinated with
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Published 27 Jul 2021

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

  • Girish Suresh Yedase,
  • Sumit Kumar,
  • Jessica Stahl,
  • Burkhard König and
  • Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

Graphical Abstract
  • benzylic alcohol selectively to the aldehyde or ketone is still desirable. Recently, cerium photocatalysis was introduced as a robust alternative to generate oxygen or carbon-centered radicals under mild reaction conditions [57][58][59][60][61][62][63][64]. CeCl3 reacts via ligand-to-metal charge transfer
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Published 23 Jul 2021

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

  • Pezhman Shiri,
  • Ali Mohammad Amani and
  • Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

Graphical Abstract
  • . This method was then extended to ketone, tosyl, and phthalimide groups on alkyl azides to produce the desired triazole derivatives. The ethylene glycol-, phenylalanine-, and glucose-derived azides were also good candidates to furnish the triazole derivatives. This protocol provides access to various
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Published 13 Jul 2021

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

  • Thiago S. Silva and
  • Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

Graphical Abstract
  • ), and notably, hydroalkylation products were produced from α-aryl ketones, from more acidic substrates like 4a, and from α-alkyl ketones, including the less activated methyl ketone 4c. Examples of intermolecular hydroalkylations of olefins using Pd were much scarcer than their intramolecular
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Published 07 Jul 2021

Total synthesis of ent-pavettamine

  • Memory Zimuwandeyi,
  • Manuel A. Fernandes,
  • Amanda L. Rousseau and
  • Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

Graphical Abstract
  • -pavettamine rather than pavettamine. Chain extension and stereoselective ketone reduction were achieved using the (R)-methyl p-tolyl sulfoxide chiral auxiliary to give the desired 1,3-syn-diol C5 unit. A protecting-group strategy was also developed for the orthogonal protection of the alcohol and amine
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Published 10 Jun 2021

Icilio Guareschi and his amazing “1897 reaction”

  • Gian Cesare Tron,
  • Alberto Minassi,
  • Giovanni Sorba,
  • Mara Fausone and
  • Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

Graphical Abstract
  • cyanoacetamide (and not a cyanoacetic ester) with a carbonyl derivative (aldehyde or ketone) was further investigated by the British chemist Jocelyn Fred Thorpe (1872–1940), a decade after the original studies by Guareschi [52]. In Thorpe’s modification, the reaction takes place in the presence of a secondary
  • ”, formally an internal redox reaction where the heterocyclic system is oxidatively aromatized and one of the substituents at C-4 reductively lost as a hydrocarbon. The reaction involves the treatment of a ketone with a solution of ethylcyanoacetate in ethanolic ammonia [7]. A precipitate of the ammonium salt
  • terms of overall redox transformation, the reaction formally “hydrolyses” a ketone into a hydrocarbon and a carboxylic acid, and the mechanism remained a black box for over a century, being eventually clarified only in 2007 by a team of British and Russian chemists [8]. One important starting
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Published 25 May 2021

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

  • Guido Gambacorta,
  • James S. Sharley and
  • Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Graphical Abstract
  • introduced to the reactor alongside cyclohexanone (65) in a single flow stream. A simple HPLC pump, mild heating (50 °C) and a residence time of 25 minutes was all that was required to give the β-hydroxy ketone 66 with >95% conversion, with modest diastereomeric ratio (dr) of 3:1 and high ee (82%). In the
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Published 18 May 2021

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

  • Joseane A. Mendes,
  • Paulo R. R. Costa,
  • Miguel Yus,
  • Francisco Foubelo and
  • Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Graphical Abstract
  • ketone derivative 111, which was not isolated. After removal of the sulfinyl group under acidic conditions, and intramolecular N-alkylation upon treatment with sodium bicarbonate, (−)-pelletierine (112) was formed, and easily isolated as its hydrochloride derivative (Scheme 32) [120]. Compound 112 is a
  • products were obtained after four additional steps: cross-metathesis of allylated compounds 120 with methyl vinyl ketone, reduction of conjugated C=C double bond, removal of the sulfinyl group under acidic conditions, and final stereoselective reduction of the imine formed by intramolecular cyclization
  • (Scheme 33) [122]. The group of Prasad reported the diastereoselective synthesis of β-amino ketone derivatives from N-tert-butanesulfinyl imines and silyl enol ethers of aryl methyl ketone [123]. The synthetic interest in β-amino ketones was exemplified in the synthesis of alkaloid (+)-sedamine (125
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Published 12 May 2021

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

  • Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

Graphical Abstract
  • Peter J. Halling WestCHEM, Dept Pure & Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland, UK 10.3762/bjoc.17.73 Abstract The kinetics of enzymatic desymmetrisation were analysed for the most common kinetic mechanisms: ternary complex ordered (prochiral ketone reduction); ping
  • -pong second (ketone amination, diol esterification, desymmetrisation in the second half reaction); ping-pong first (diol ester hydrolysis) and ping-pong both (prochiral diacids). For plausible values of enzyme kinetic parameters, the product enantiomeric excess (ee) can decline substantially as the
  • -reductases. The reductant (usually NADH or NADPH) has to bind first to the enzyme, followed by the prochiral ketone in the second step. The chiral products are then released before the oxidised co-product. “Ping-pong, second”. Followed by most transaminases and lipase or esterase-catalysed acylation of
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Published 21 Apr 2021
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