Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• well-defined polymer brushes from polymer surfaces [170][171]. Photoinduced processes, including photoATRP and PET-RAFT were used [172][173][174][175]. Poly(aryl ether ketone)s such as poly(ether ether ketone), bearing a diaryl ketone moiety resembling that of benzophenone, can generate biradicals upon

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• 196.1 for a ketone group, 169.2 and 165.6 attributed to oxygenated aromatic carbons, and three other signals at δC 109.4, 106.2, and 16.6 (Figure S6 in Supporting Information File 1). On the other hand, each of the two aromatic methyl signals displayed a set of three cross peaks; the first one at δH

• 2.09 with the carbon signals at δC 165.6, 122.0, and 120.3, and the second one at δH 2.02 with the carbon signals at δC 169.2, 165.6, and 106.2 (Figure 2). These findings clearly indicated the presence of the 1,3-dimethylbenzene moiety linked to a side chain containing an ethyl group and a ketone group

• and 28.8. Hence, these key correlations permitted to assign the attachment of the hemiketal carbon (δC 106.1) to the ketone group and the benzene ring. Based on the above evidence, the structure of 1 was assigned with a trivial name of 5,7-dimethylpseudopithonone (Figure 1). Pseudopithonone was

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• reductive elimination to yield ketone 78. In the acylthiolation cycle, the azaphilic ZnCl2 activated NTSE 1’’’ via N–Zn coordination to facilitate the leaving ability of succinimide. Then, nucleophilic substitution of arylmagnesium bromide 75 to intermediate IV provided thioester 79. In 2022, Gao and co

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• by X-ray analysis (see Supporting Information File 1). Both, hydroxy ketone 1 and the corresponding enone 2, can be converted into the same indanone 3 in comparable yields; see pairs of reactions for 1a and 2a (indanone 3a), 1d and 2d (indanone 3d), 1i and 3i (indanone 3i), and 1n and 3n (indanone 3n

• -rich enones 2o,t,u, bearing electron-donating substituents in the aromatic rings, afford complex mixtures of oligomeric materials. The cyclization of hydroxy ketone 1k into indanone 3k is accompanied by demethylation of one of the methoxy groups (Scheme 6). The positions of hydroxy and methoxy groups

• delocalization of the positive charge from the carbonyl group to the aromatic ring. It should be mentioned that cation Bm was generated by two ways in TfOH: either directly by protonation of enone 2m or from hydroxy ketone 1m. The latter was found to undergo fast dehydration into enone 2m in TfOH at room

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• and the use of a ketone was necessary to induce C–H functionalization selectivity in preference to C=C functionalization. The products were obtained in moderate to high yields (Scheme 67). 2.6 N–H and C(sp2)–H carboxylation The application of the [(IPr)CuOH] complex as catalyst for the N–H/C(sp2)–H

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• the alkynyl-substituted 1,2-oxazin-4-ol derivative 19 which is smoothly available from the corresponding ketone 6 by highly stereoselective reduction with sodium borohydride [53]. Starting from 1,3- (8) or 1,4-bis(bromomethyl)benzene (16), respectively, the approved conditions in the presence of TBTA

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• elegant strategies on direct conversion of in situ-activated carboxylic acids for ketone synthesis [27][35][38], we chose dimethyl dicarbonate (DMDC, A1) as the activating reagent. To our delight, the reaction of 1a and 2 in the presence of NiBr2(dtbbpy) (10 mol %), Hantzsch ester (HE) and A1 in DMAc

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• phosphate moiety was introduced via the use of bromoethyl dichlorophosphate 11.4 to produce 11.5. The reduction of the ketone with NaBH4 produced 11.6, and then the incorporation of the trimethylammonium group produced deoxy-lyso-PAF 11.7. Finally, the acetylation of the secondary alcohol produced racemic

• bio-imaging purposes [144]. In 1995, Mauleón et al. [145], extended this study by reporting the incorporation of a phenyl group in ω-position or by adding an alkyl group, a ketone or an alcohol function as illustrated in Figure 33. The idea of

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• extract a hydrogen from the ether C (sp3)–H bond to form radicals. Subsequently, a single electron transfer (SET) leads to the oxonium species. Then, the enamine generated in situ from methyl aryl ketone and pyrrolidine undergoes a nucleophilic reaction with the oxonium species followed by hydrolysis to

• ketones 94 with ethers [81]. Contrary to what was obtained for the alkylation of coumarin at the carbonyl α-position, vinyl ketone undergoes Michael addition and ether addition at the β-position of the carbonyl (Scheme 20). The reaction delivered various alkylation products in good to excellent yields

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

• Olfa Mhasni,
• Jalloul Bouajila and
• Farhat Rezgui

Beilstein J. Org. Chem. 2023, 19, 1251–1258, doi:10.3762/bjoc.19.93

• ketone-derived alcohols such as 1d (EWG = COPh, R = H), 1e (EWG = COn-Pr, R = H), 1f (EWG = COc-C6H11, R = H) [42], and imidazole under the established reaction conditions and we have observed that the conversion was complete but was not clean. However, in methanol at reflux a clean reaction took place

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• oxidation noted that the corresponding dimethyl amine – p-benzaldehyde oxidized at 0.79 V vs Fc/Fc+ and underwent a slow re-reduction [73]. Similar compounds, ketone derivatives rather than aldehyde, were developed with more negative potentials as anolytes for aqueous and non-aqueous RFBs by Sanford and co

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• into a ketone moiety diminished the activity [31]. Similar findings on the related polyporenic acid B, with significant IC50 values between 8.4–12.2 µM [22], confirms the probable crucial role played by the 3-OH group in improving the potency. The presence of the 3-O-methylglutaroyl functionality in

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• provided ketone 138 which was reacted with an α-keto ester in an intramolecular 5-endo-trig-cyclization process to afford 139. Treatment of compound 139 with sodium borohydride afforded secondary alcohol 140 which after conversion of the tosyl group into a methyl group gave the final product 141 (Scheme 35

Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 789–799, doi:10.3762/bjoc.19.59

• attributable to two methyl groups, two methoxy carbons, one methylene, three methines (one sp2 and one of them oxygenated), one ketone, and five sp2 carbons (two of them oxygenated). Some of these signals resemble those of 8-O-methylteratosphaerone B [17], suggesting compound 1 being an analogue, but with an

• NMR and DEPT spectra (Table 2 and Figure S9 in Supporting Information File 1) show that compound 2 is comprised of 9 carbons, including one methyl, one methoxy carbon, one sp2 methine, one ketone, and five sp2 carbons (three of them oxygenated). The 1H and 13C NMR data and the molecular formula

• -tetrasubstituted benzene substructure. The 13C NMR and DEPT spectra of 3 (Table 2 and Figure S15 in Supporting Information File 1) exhibit 15 resonances classified into two methyls, four sp2 methines, one ketone, and eight sp2 carbons (four of them oxygenated). The two methyl groups are positioned at C-3 and C-5

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• dibenzocyclooctyne 8 and tetracyclone 2 in a 91% yield. After a subsequent sequence of deprotection and oxidation, ketone 10 was obtained. Through the oxidative cyclodehydrogenation reaction of 10 in the presence of DDQ and trifluoromethanesulfonic acid (TfOH), a saddle-helix hybrid nanographene 11, bearing an

• this [7]helicene family by introducing different linkers such as nitrogen, sulfur, sulfone, ketone, methylene, and derivatives of ketone [44]. Due to the varied nature of the different linkers, the photophysical and semiconductor properties can be effectively tuned. Feng and co-workers reported a

• the P,P, and M,M enantiomers. The isomerization barrier was determined as 44.7 kcal/mol at 260 °C by HPLC analysis. Meanwhile, Campaña and co-workers reported a similar chiral, tropone-containing HBC-dimer 53 [47]. Ketone 47 was transformed to compound 48 by reacting with 1-iodo-4-(phenylethynyl

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• . Therefore, numerous structurally distinct substrates were successfully utilized. Other than nitroolefins, Liao and co-workers have observed a side reaction of the α,β-unsaturated ketone 26 and the enolate 27 when they studied the conjugate addition of R2Zn reagents to chalcone and its derivatives (Scheme 7A

• nucleophile (R3Zn−) to the ketone with moderate yields but still good stereoselectivities (Scheme 9B). In 2018, Wang and co-workers extended the group of applicable electrophiles for the zinc enolate-based tandem reactions. Following the conjugate addition of Et2Zn to acyclic α,β-unsaturated ketones 41, they

• , which begins with a Cu-catalyzed enantioselective conjugate addition/enolate alkylation tandem reaction sequence utilizing the N-heterocyclic carbene ligand L40 [112]. Ketone 232 was isolated in 61% yield and 81% ee. Hereafter, the authors were able to synthesize the complex tetracyclic structure within

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• -trifluoromethyl substituent forming the ketone product in <10% yield. While substitution of the norbornene was tolerated, both EWGs and EDGs hindered the reaction. Upon several mechanistic studies, the authors proposed the catalytic cycle begins with the oxidative addition of the active Ni(0) catalyst to imide 27

• transition metals, this reaction proceeded smoothly with a broad range of ester-, ketone-, and amide-stabilized phosphorus ylides. Oxabenzonorbornadienes bearing both EWG and EDG substituents worked well including bridgehead-substituted substrates which only experienced a slight reduction in yield. Similar

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• the literature all target similar disconnections, especially an aldol strategy involving a recurrent 4-acetyl-1,3-thiazolidin-2-one ketone partner. Herein, we describe an alternative disconnection and subsequent stereoselective transformations to construct a stereopentade amenable to latrunculin and

• disconnection strategies for the macrocycle or the lactol formation (Figure 2, left), and for the aldol reaction leading to 4, using a 4-acetyl-1,3-thiazolidin-2-one 5 as ketone partner (Figure 2, route A). Strikingly, this last disconnection was adopted in all previous syntheses to form the (15,16)- or the

• (13,14)-bond of 1 and 2, respectively. Conversely, we envisaged an alternative disconnection to form the (16,17)- or the (14,15)-bond of 1 and 2, through an aldol reaction of aldehyde 8 readily available from ʟ-cysteine, leading to aldol adduct 7 (Figure 2, route B). The methyl ketone partner 9 could be

Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• a B‒O/B‒H transborylation in catalysis was the catalytic Midland reduction of propargylic ketones developed by Thomas to give enantioenriched propargylic alcohols (Scheme 10) [74]. The reaction was proposed to occur by enantioselective reduction of the propargylic ketone 42 by myrtanyl borane 43 to

• isotopic labelling and proposed to proceed by hydroboration of the allene 62 by the borane catalyst (H-B-9-BBN or 10-phenyl-9-borabicyclo[3.3.2]decane [Ph-BBD]) followed by rapid isomerisation from the (Z)-63 to (E)-allylborane 64 which underwent allylation of the ketone 65 to give an allylic borinic ester

• '-binaphthyl (MTBH2) with LiAlH4 as the catalyst gave good yields of the alcohol (70–80%) after workup, but in low enantioselectivities (1–6% ee). A mechanism was proposed whereby reduction of the ketone 91 by the aluminium hydride 92 was followed by Al‒O/B‒H exchange with HBcat (Scheme 23). Roesky reported

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• % yield [17][18]. This key intermediate was then converted into ketone 19 in 11 steps leading to the desired dicyclopenta[a,d]cyclooctane structure 21 [19]. As explained by the authors, the RCM reaction was not as easy as expected and extensive work was necessary to accomplished the construction of this

• and access to cotylenin A aglycon 50. Other examples of fusicoccan derivatives are represented by alterbrassicicene D (54) and 3(11)-epoxyhypoestenone (55), recently isolated from Hypoestes verticillaris [32]. Structurally, alterbrassicicene D (54) comprises an α,β-unsaturated ketone C-ring, and a

• single hydroxy group on the central eight-membered ring and 3(11)-epoxyhypoestenone (55) shows a surprising oxa-bridge between the A and C rings, an α,β-unsaturated ketone on ring C, and an endo-alkene into the cyclooctene ring. Recently, Chen et al. reported the synthesis of the tricyclic core structure

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• combined computational and experimental approach that in this enzyme the main chain carbonyl oxygen of Gly182 near the helix G kink and an active site water are involved in the deprotonation–reprotonation sequence in the biosynthesis of 10 (Scheme 8B) [69]. γ-Selinene (10) has been synthesised from ketone

Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

• Benedikt Kolb,
• Daniela Silva dos Santos,
• Sanja Krause,
• Anna Zens and
• Sabine Laschat

Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17

• by a hydrozirconation/acylation sequence. Examples of biologically active compounds with (2Ε,4E)-unsaturated ketone units. Selected examples for the synthesis of conjugated dienones from the literature [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Previous work of hydrozirconations

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• the ratio of the minor diastereomers, the ketone mixture was treated with NaOMe, resulting in epimerization of 9, arriving at a 3:3:1 mixture of 9, 10, and 11. Unfortunately, a moderate amount of material was lost due to competing aldol reactions of the ketones. While compound 9 was epimerized to a

• large extent into 10, the isomer 11 could not be converted into the respective trans-fused compound. This inseparable ketone mixture was then quantitatively converted into the target cadinols by addition of methylmagnesium bromide [15]. Major compounds were cedrelanol or τ-cadinol (13) and δ-cadinol (12

• configuration. Controlling the stereogenic center C-4 of 4 would allow access to the respective enantiomers. Unfortunately, enantiomerically pure 4 is not easily available, in contrast to ketone 17. This compound can be obtained in high optical purity using Jørgensen’s organocatalyst 16 [20][21]. In addition

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

• Qian-Ci Gao,
• Yi-Fei Li,
• Jun Xuan and
• Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

• desired product 3ia was successfully obtained in 84% yield (1.1 g) via a simple recrystallization from the reaction mixture (Scheme 4a). In the presence of hydroxylamine hydrochloride, the carbonyl group of the ketone can be selectively converted into an oxime product 4 (Scheme 4b, 71% yield). In addition