Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• ]. Also, the effects of fluorination on the chiroptical features of [n]helicenes were theoretically predicted [41]. In addition to the manipulation of electronic natures, partial fluorination of PAHs has been recognized to be significant for crystal design and engineering. Thus, molecular packing patterns

• progression. The first phosphorescence vibrational peak was observed at 501 nm for PIC and 514 nm for FUL [48]. In the case of F8-phenacenes, at 77 K, in addition to fluorescence bands, photoluminescence bands assignable to phosphorescence were detected (λPHOS = 518 nm for F8PIC, 528 nm for F8PIC, and 525 nm

Asymmetric synthesis of fluorinated derivatives of aromatic and γ-branched amino acids via a chiral Ni(II) complex

• Maurizio Iannuzzi,
• Thomas Hohmann,
• Michael Dyrks,
• Kilian Haoues,
• Katarzyna Salamon-Krokosz and
• Beate Koksch

Beilstein J. Org. Chem. 2025, 21, 659–669, doi:10.3762/bjoc.21.52

• chiral nickel complexes. In recent years, the Soloshonok working group demonstrated the synthesis of non‑natural amino acids using the corresponding chiral Ni(II) complex [7]. In addition to the high enantiomeric purity of the corresponding products, the scale of the reaction, which extends into the

Recent advances in allylation of chiral secondary alkylcopper species

• Minjae Kim,
• Gwanggyun Kim,
• Doyoon Kim,
• Jun Hee Lee and
• Seung Hwan Cho

Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51

• importance of reaction conditions after ZnCl2 addition (Scheme 5). When the reaction mixture was stirred at −30 °C for 1 hour (entry 1 in Scheme 5), the product 19 maintained a high diastereomeric ratio (dr), indicating minimal racemization. However, extending the stirring time or increasing the reaction

• optimization revealed LiOt-Bu and diphenyl phosphate as the optimal metal alkoxide and leaving group, delivering the desired product 32 in high yield and high enantioselectivity at room temperature with only 2 mol % catalyst loading. The scope of this transformation proved to be remarkably broad. In addition

• traditional crotyl addition to acetaldehyde. This methodology represents the first example of highly enantio- and diastereoselective copper-catalyzed allylic substitution that controls vicinal stereogenic centers. DFT calculations revealed that the high enantioselectivity (98:2 er) originates from a face

Entry to 2-aminoprolines via electrochemical decarboxylative amidation of N‑acetylamino malonic acid monoesters

• Olesja Koleda,
• Janis Sadauskis,
• Darja Antonenko,
• Edvards Janis Treijs,
• Raivis Davis Steberis and
• Edgars Suna

Beilstein J. Org. Chem. 2025, 21, 630–638, doi:10.3762/bjoc.21.50

• , and afforded trace amounts of 6h together with the corresponding acyclic hemiaminal 10h as the major product. Such an outcome can be attributed to a slower formation of a 6-membered ring [15] from transient N-acyliminium species. Gratifyingly, the addition of KOH (1 equiv) to the electrolysis mixture

• facilitated the cyclization, and the 6-membered heterocycles 6h,i could be obtained in 27% and 18% yield, respectively. In addition to sulfonamides, carbamates such as N-Boc and benzamide are also suitable as nucleophiles for the anodic decarboxylation/cyclization reaction. However, the corresponding 2

• -aminoproline derivatives 6j,k were obtained in considerably lower yields (38%) as compared to those of N-Ts analog 6a. Surprisingly, the addition of KOH (0.5 equiv) to the electrolysis solution has helped to improve yield of N-Boc-protected 2-aminoproline derivative 6j from 38% to 59%. However, the addition of

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• functionalized nature of polypeptides/proteins demands exquisite selectivity to target specific sites on the macromolecule of interest. In addition to the requisite features of the chemical methods outlined above, there are key requirements for synthetic methods used in ADCs, which include high site-selectivity

• particularly useful and important tool in which azides and other dipolar species engage with reactive alkenes and alkynes on non-canonical amino acids [20]. Transition-metal-mediated processes, including metathesis reactions, aryl cross-coupling reactions, and conjugate addition reactions with dehydroalanine

• transformations is a strong electrophile that can react with Tyr, for instance, if such an amino acid is located near the reactive site. In addition, command of the DAR might have some limits, as the distance between the catalyst and the mAbs is not well defined, meaning that the photoredox reaction might not

Semisynthetic derivatives of massarilactone D with cytotoxic and nematicidal activities

• Rémy B. Teponno,
• Sara R. Noumeur and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 607–615, doi:10.3762/bjoc.21.48

• % yield) obtained as a white powder. Its molecular formula C27H31ClO10 was deduced from the HRESIMS spectrum (Figure S2, Supporting Information File 1), which exhibited the sodium adduct at m/z 573.1495 (calcd. for C27H31ClO10Na+: 573.1498) and NMR analysis. In addition to resonances attributed to

• the presence of catalytic amounts of 4-dimethylaminopyridine, 82% yield) was proposed as C32H23Br3O9 based on the molecular ion cluster sodium adducts [M + Na]+ depicted at m/z 810.96, 812.94, 814.92, and 816.90 characteristic for the presence of three bromine atoms [22]. In addition to signals

• Information File 1) which showed the protonated molecular ion peak and the sodium adduct at m/z 325.1281 [M + H]+ (calcd. for C16H21O7+: 325.1282) and 347.1103 (calcd. for C16H20O7Na+: 347.1101), respectively. Its 1HNMR spectrum displayed in addition to signals ascribed to massarilactone D, those of a

Total synthesis of (±)-simonsol C using dearomatization as key reaction under acidic conditions

• Xiao-Yang Bi,
• Xiao-Shuai Yang,
• Shan-Shan Chen,
• Jia-Jun Sui,
• Zhao-Nan Cai,
• Yong-Ming Chuan and
• Hong-Bo Qin

Beilstein J. Org. Chem. 2025, 21, 601–606, doi:10.3762/bjoc.21.47

• acidic conditions as key step to construct an aryl-containing quaternary center. The 6/5/6 benzofuran unit was formed through reductive elimination with Zn/AcOH and a spontaneous oxy-Michael addition. This synthesis consists of 8 steps and achieves an overall yield of 13%, making it the shortest known

• construct the aryl and allyl-containing quaternary center, and a simultaneous phenol-initiated oxy-Michael addition to afford the benzofuran unit. This synthesis took 9 steps and achieved an overall yield of 13%. Also in 2024, the Denton group reported another efficient way to access the 6/5/6 benzofuran

• scaffold of simonsol C, utilizing an alkaline dearomatization as the key reaction, followed by a functional-group-selective Wittig reaction and concurrent oxy-Michael addition [6]. A bromophenol acetal was used in the intramolecular alkylative dearomatization, which was first reported by Magnus et al. [8

Sequential two-step, one-pot microwave-assisted Urech synthesis of 5-monosubstituted hydantoins from L-amino acids in water

• Wei-Jin Chang,
• Sook Yee Liew,
• Thomas Kurz and
• Siow-Ping Tan

Beilstein J. Org. Chem. 2025, 21, 596–600, doi:10.3762/bjoc.21.46

• copper(I)-catalyzed reactions (48–71%) [13] and the four-component Ugi reaction [14] yields 48–71% and 27–67%, respectively. In addition, pyroglutamates with isocyanates, which provide exceptionally high yields (97–99%) [15], and dipeptides have been utilized in triflate-activated Mumm’s rearrangement

• second step was attempted as part of a one-pot synthesis of hydantoins by the addition of concentrated hydrochloric acid followed by microwave irradiation of the reaction mixture at 80 °C for 15 min (Scheme 2). Gratifyingly, the acid-induced intra-cyclization of the urea derivative H1a proceeded smoothly

• ][15][16], but reaction times are significantly shorter. In addition, TLC analysis confirmed complete consumption of starting material, which was further confirmed by NMR analysis showing no detectable impurities or unreacted starting material. Variations in yields (34–89%) may be due to differences in

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• decompose into DMS (dimethyl sulfide), which then can act as a nucleophile in several MCRs (Scheme 4) [19][20][21][22]. In this context, DMSO can be used as a source of the methylsulfanyl (-SCH3) group after DMS follows a nucleophilic addition or substitution, allowing one to obtain different types of

• nucleophilic species present in the reaction medium, MMS can act as a methylene source. Under hydrolysis conditions, it can be a source of formaldehyde (Scheme 5a), but with other nucleophiles, after nucleophilic addition, the sulfide group can work as a leaving group, allowing for a sequential domino process

• developed in which the alkene compound has been replaced with other surrogates for electrophilic addition, such as ketones [32][33][34]. In the case of the carbonyl component, it is generally an aromatic aldehyde [30][33][34] and there are not many reports on using formaldehyde in the Povarov reaction. In a

Study of the interaction of 2H-furo[3,2-b]pyran-2-ones with nitrogen-containing nucleophiles

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2025, 21, 556–563, doi:10.3762/bjoc.21.44

•  4). The suggested method allows one to utilize arylhydrazines both with donor and acceptor substituents in the aromatic ring. Besides that, heterocyclic hydrazines also can be used in the considered transformation. In addition, we have tried to carry out the process under investigation with

• established by X-ray analysis. The proposed mechanism of the considered processes is outlined at Scheme 8. Initially, the free nitrogen nucleophile is reversibly generated from the corresponding hydrochloride or acetate. Next, acid-catalyzed addition of the amine component to the carbon atom of the aroyl

Asymmetric synthesis of β-amino cyanoesters with contiguous tetrasubstituted carbon centers by halogen-bonding catalysis with chiral halonium salt

• Yasushi Yoshida,
• Maho Aono,
• Takashi Mino and
• Masami Sakamoto

Beilstein J. Org. Chem. 2025, 21, 547–555, doi:10.3762/bjoc.21.43

• developed chiral halonium salts and applied them to asymmetric reactions such as vinylogous Mannich reactions of cyanomethylcoumarins 6 with isatin-derived ketimines 7 [33][35] and 1,2-addition reaction of thiols to ketimine [34], which formed the corresponding products 8 in high yields with high to

• amide moiety and with almost no enantioselectivity. Although the addition of a catalytic amount of 9e accelerated the reaction, the same diastereomer of 17b as the major product was obtained as for the reaction without a catalyst, which shows the importance of halonium salt moieties in our catalysts

Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• moiety in the amino acid. This hypothesis is also supported by the significant quenching of the fluorescence of the naphthalene unit in 1 upon addition of increasing amounts of H-Trp-OH to the solution. Additionally, cation–π interactions between the ammonium cation of the guest and the naphthalene of

• fluorescence measurements where a strong quenching of the naphthalene fluorescence upon addition of each of the Trp-containing tripeptides 2–7 was observed. For peptides 2 and 3 interactions of the receptor with the N-terminal ammonium cation are likely also involved in the binding process (Figure 5). This is

• – a chemoselective receptor for aromatic amino acid esters in water. Fluorescence emission spectra of receptor 1 (25 μM in H2O) upon addition of increasing amounts of tripeptide 2. The concentration of the guest corresponding to each curve is indicated on the right. The arrow marks the quenching of

Vinylogous functionalization of 4-alkylidene-5-aminopyrazoles with methyl trifluoropyruvates

• Judit Hostalet-Romero,
• Laura Carceller-Ferrer,
• Gonzalo Blay,
• Amparo Sanz-Marco,
• José R. Pedro and
• Carlos Vila

Beilstein J. Org. Chem. 2025, 21, 533–540, doi:10.3762/bjoc.21.41

• Judit Hostalet-Romero Laura Carceller-Ferrer Gonzalo Blay Amparo Sanz-Marco Jose R. Pedro Carlos Vila Departament de Química Orgànica, Facultat de Química, Universitat de València, Dr Moliner 50, 46100 Burjassot, València, Spain 10.3762/bjoc.21.41 Abstract A valuable vinylogous addition reaction

• properties along a C=C double bond [1]. This effect has been established to be very advantageous to expand the range of reactions of different functional groups that can be coupled efficiently through a conjugated π-system. In this context, the addition reaction of vinylogous nucleophiles to carbonyl

• compounds is a significant and important reaction for the selective synthesis of homoallylic alcohols in an efficient and sustainable way [2][3]. As carbonyl compounds, alkyl trifluoropyruvates [4][5] are an interesting class of compounds that have been used in addition reactions of different nucleophiles

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• ANTH and the –C6F5 group might provide the desired spatial isolation of the ANTH (and other PAH) cores, and result in enhanced photoluminescence by disrupting close π–π stacking in the solid state. In addition, air- and photostability might also be improved due to the steric and electronic properties

• of multiple BnF substituents. For example, C5-pentakis(BnF)corannulene (C5-CORA(BnF)5) [18][19] exhibited improved acceptor strength relative to unsubstituted CORA due to the electron-withdrawing BnF groups (which are similar to the electron-withdrawing properties of CF3 groups [18][19]). In addition

• reactions) Dry Mg turnings (excess) were added to an oven-dried 100 mL Schlenk flask and mechanically activated via stirring and heating. After 1 h, dry THF (20 mL) and 9,10-ANTH(Br)2 (84 mg, 0.25 mmol) were added. Several activation methods were tried (ultra sonic bath, careful heating, addition of I2

Synthesis of the aggregation pheromone of Tribolium castaneum

• Biyu An,
• Xueyang Wang,
• Ao Jiao,
• Qinghua Bian and
• Jiangchun Zhong

Beilstein J. Org. Chem. 2025, 21, 510–514, doi:10.3762/bjoc.21.38

• has been found to damage 246 grain commodities, especially starchy products [2][3]. In addition, the adult T. castaneum secretes carcinogenic methyl-1,4-benzoquinone and ethyl-1,4-benzoquinone to inhibit the microorganisms and the predators [4][5]. Therefore, T. castaneum infected stored products are

Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction

• Thomas Brandt,
• Pascal Lentes,
• Jeremy Rudtke,
• Michael Hösgen,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36

• subsequently activated with light at the site of illness with high spatiotemporal resolution. Thus, collateral damage in the surrounding healthy tissue can be avoided. In addition, the quantitative thermal back-isomerization from the active E to the inactive Z configuration prevents contamination and

Synthesis of electrophile-tethered preQ₁ analogs for covalent attachment to preQ₁ RNA

• Laurin Flemmich and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 483–489, doi:10.3762/bjoc.21.35

• reductive amination to form the hydroxyalkyl handles, which were further converted to the haloalkyl or mesyloxyalkyl-modified target compounds. In addition, we report hydrogenation conditions for preQ0 and DPQ0 that allow for cleaner and faster access to preQ1 compared to existing routes and provide the

• preQ1 congeners into oligonucleotide strands at specific recognition sites. In addition, the potential of modified preQ1 for protein enzyme-independent RNA labeling has also been demonstrated [12][17]. In a recent study [4], sequence-specific RNA–small molecule crosslinking (Scheme 1B) was achieved in

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• organometallic catalysis [15], enzymatic catalysis [16], aminocatalysis [17][18][19], and hydrogen-bonding catalysis [20][21][22]. The Michael addition reaction is a versatile synthetic methodology that allows the formation of new carbon–carbon and carbon–heteroatom bonds through the coupling of electron-poor

• organocatalytic synthesis of 2-cyclohexen-1-ones via a Michael/Michael/retro-Michael cascade reaction [31]. Our research has shown that the Jørgensen–Hayashi catalyst [32][33] is a highly promising organocatalyst, facilitating enantioselective Michael addition reactions with high yields and excellent levels of

• conditions tested. Similarly, the resolution of nitro aldehydes 16 and 17, prepared by Michael addition of nitromethane to α,β-unsaturated aldehydes (entries 16 and 17, Table 5), was tested, and the same results were obtained as in the cases of the malonate derivatives. These results indicate that dicarbonyl

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• improve the result. However, the addition of a LAG agent (MeOH, 50 μL) in the automated grinding step dramatically improved the outcome (quantitative conversion after 20 h of irradiation). Intriguingly, the simultaneous LAVG and irradiation enabled the formation of 5.3 in 97% yield upon reduced

• . Also in this case, the addition of toluene was beneficial and excellent yield of the corresponding product (10.2) was observed in 30 h of reaction. As a comparison, the latter reaction required 48 h in solution. Intriguingly, 10.3 could in turn be synthesized via a mechanochemical Suzuki coupling

• benefits of the photomechanochemical approach in the field of synthesis [77]. Specifically, they developed photomechanochemical conditions for the atom-transfer-radical addition (ATRA) of sulfonyl chlorides to alkenes, pinacol coupling of carbonyl compounds, decarboxylative acylation, and photocatalyzed [2

Electrochemical synthesis of cyclic biaryl λ³-bromanes from 2,2’-dibromobiphenyls

• Andrejs Savkins and
• Igors Sokolovs

Beilstein J. Org. Chem. 2025, 21, 451–457, doi:10.3762/bjoc.21.32

• ]. In addition, cyclic diaryl λ3-bromanes have been successfully employed as halogen-bonding organocatalysts in Michael addition [8] and their chiral variants were efficient in catalyzing enantioselective Mannich reactions of ketimines with cyanomethyl coumarins [9] and malonic esters [10]. These

• ) experiments (0.1 M TBA-BF4 in HFIP on a Pt disk electrode) revealed that the reduction current increases almost 4 times upon the addition of 5 mM 1a to the electrolyte (see Supporting Information File 1, Figure S1). At the same time, passing 6.0 F through a solution of 1a in 50 mM TBA-BF4/HFIP at j = 8 mA·cm

Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• addition of base). Furthermore, since substrate binding is weak in this system (≈1 kcal/mol), the potential to alter the cage periphery to direct site-selective reactivity inside the cavity is enormous. Because the reaction is oriented precisely with respect to the cage axis, catalysis becomes amenable to

• more likely to organize substrate selectivities than provide large transition-state stabilizations. This follows from the requirement for differential transition-state binding over substrate binding for catalysis [100], and requires cavities that polarize in addition to organizing, that is, an

Identification and removal of a cryptic impurity in pomalidomide-PEG based PROTAC

• Bingnan Wang,
• Yong Lu and
• Chuo Chen

Beilstein J. Org. Chem. 2025, 21, 407–411, doi:10.3762/bjoc.21.28

• addition intermediate is stabilized by an oxygen atom only. As such, the erosion of 3 by taurine was minimal. Conclusion Nucleophilic aromatic substitution of 4-fluorothalidomide (1) has provided a convenient entry to the IMiD class of PROTAC molecules. Although the yield of the desired product is

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• (Scheme 12). In addition to the sulphonate groups, Crich et al. also explored the role of 2-O-cyanoester as the participating groups at the C-2 position for the formation of β-rhamnoside moieties. However, 2-O-cyano ester 69 showed complete α-selectivity when glycosylated with glycosyl acceptor 67 with no

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• thermodynamically more stable than the corresponding (OH) forms. Increasing the polarity of the medium additionally enhances their stabilization. The introduction of an additional acceptor substituent to the tropolone moiety has a similar effect. In addition, compared to compounds 7a,b, compounds 8a,b show a marked

• the 7,8 (OH) form and is caused by the excited-state intramolecular proton transfer (ESIPT) process due to intramolecular O→N proton migration in the singlet excited state [26][27]. The ionochromic sensitivity of compounds 7a,b and 8a,b to anions was investigated in acetonitrile upon addition of tetra

• sensitivity of in situ obtained complexes 9 and 10 with CN− to different cations. It appeared that the addition of an equivalent amount of Hg(ClO4)2 to an acetonitrile solution selectively and completely restores the initial absorption and fluorescence spectra (Scheme 3). Thus, the obtained compounds

Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• fashion. In addition, these compounds showed very low to no inhibition of human colon cancer cell line (HCT-116), with the exception of compound 7l which reduced the cell viability about 63% and is currently further investigated. Based on the above findings, compound 7b and 7h are considered

• Dried acetonitrile (10 mL) was used to prepare a solution of compound 5 (251 mg, 1.0 mmol) followed by addition of anhydrous K2CO3 (173 mg, 1.25 mmol) under continuous stirring and heating. After 30 minutes, the solution of the respective 2-chloro-N-aryl/benzyl/cyclohexylacetamide 6a–h (1 mmol) in dry

• -benzothiazine-N-aryl/benzyl/cyclohexylacetamides 7i–n Dried acetonitrile (10 mL) was used to prepare a solution of compound 5 (1.0 mmol, 251 mg) followed by the addition of anhydrous K2CO3 (297 mg, 2.15 mmol) under continuous stirring and heating. After 30 minutes, the solution of respective 2-chloro-N-aryl