Cyclodextrins as building blocks for new materials

• Miriana Kfoury and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2023, 19, 889–891, doi:10.3762/bjoc.19.66

• their biodegradability [4], negligible toxicity, and excellent safety profile [5]. In addition, CDs offer a further step towards sustainability, making them suitable for a wide range of uses in various fields. Accordingly, the global market size of CDs is expected to grow to nearly US$ 390 million by

• other neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and Huntington’s diseases. Due to their ability to extract cholesterol, treatment with CDs could reduce atherogenesis and atherosclerotic plaque size by solubilizing cholesterol crystals [9]. In addition, CDs can sequester cholesterol

• , and so on [14][15][16][17]. In addition to bearing a rigid skeleton, CDs act as versatile multitasking agents. They add value to these composites as their cavities remain generally available to accommodate active substances, or they work as supramolecular catalysts or molecular concealers. Due to the

Asymmetric tandem conjugate addition and reaction with carbocations on acylimidazole Michael acceptors

• Brigita Mudráková,
• Renata Marcia de Figueiredo,
• Jean-Marc Campagne and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 881–888, doi:10.3762/bjoc.19.65

• 10.3762/bjoc.19.65 Abstract We present here a stereoselective tandem reaction based on the asymmetric conjugate addition of dialkylzinc reagents to unsaturated acylimidazoles followed by trapping of the intermediate zinc enolate with carbocations. The use of a chiral NHC ligand provides chiral zinc

• obtained by other conjugate addition reactions. Keywords: acylimidazole; asymmetric catalysis; carbocation; conjugate addition; enolate; Introduction Asymmetric metal-catalyzed conjugate additions provide access to numerous chiral scaffolds. This type of C–C bond formation efficiently enables the

• , because of their particular chemical and physical properties [15]. In addition to ester/amide synthesis, enoyl imidazolides were developed as excellent Michael acceptors. Acylimidazoles are unique electrophiles that demonstrate moderate reactivity, relatively high stability, chemical selectivity, and high

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• detection of heavy metal ions. Results and Discussion The interactions of G with TMeQ[6] UV–vis spectroscopy analysis The binding interaction between G and TMeQ[6] in aqueous solution was studied using UV–vis absorption spectroscopy. Figure 2a shows that the absorbance of G decreases with the addition of

• at a wavelength of 350 nm. With the continuous addition of TMeQ[6], the fluorescence intensity of G is continuously enhanced, and the wavelength is redshifted to 391 nm, indicating that TMeQ[6] interacts with the guest molecule G. The TMeQ[6] cavity may limit the rotation of the pyridine ring on the

• other metal cations) in aqueous solution was investigated using fluorescence spectroscopy. It was found that the G molecule had no specific fluorescence response to the above metal cations (Figure 5a). Interestingly, the addition of the Hg2+ ion to the G@TMeQ[6] system caused a strong fluorescence

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• of several methods for the synthesis of functionalized pyridines or their integration into an organic molecule, new methodologies for the direct functionalization of pyridine scaffolds have been developed during the past two decades. In addition, transition-metal-catalyzed C–H functionalization and

• materials [1][2][3][4][5][6][7][8][9][10]. Due to its different characteristics such as basicity, stability, water solubility, small molecular size, and ability to form hydrogen bonds, pyridine continues to be a suitable moiety in organic synthesis. In addition, it has been observed that pyridine rings

• . In addition, the lone pair electrons of the nitrogen atom interact with Lewis acids instead of the π-electrons of the ring system thus resulting to its reduced reactivity for electrophilic aromatic substitution reactions, such as a Friedel–Crafts reaction [21][22][23]. Hence, it is challenging to

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• . The addition of a strong thiophile (Ph3P; Table 1, entry 5) does not turn the reaction toward the ECR, and only several other decomposition products can be detected together with 8a. Triethylamine causes the decomposition of salt 6a in both polar aprotic solvents (Table 1, entries 2 and 6). In MeCN

• where TEA behaves as a stronger base, the presence of benzonitrile was proved in the 1H NMR spectrum of the crude reaction mixture. On the other hand, the addition of 3 equivalents of a mild base (solid KHCO3; pKa = 6.35 in water [30]) into the DMF solution or MeCN suspension of salt 6a leads to the

• phosphite does not give 8a-Me at all. The combined yield of 8a and 8a-Me can be increased when trifluoroacetic acid is added (Table 1, entry 9). Its role probably involves an acid-catalyzed elimination of a water molecule from 7a or 7a-Me. On the other hand, the addition of a stronger base (triethylamine

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

• Ksenia Malkova,
• Andrey Bubyrev,
• Stanislav Kalinin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60

• carbonyl group deactivation. Furthermore, while implementing the protocol for 2-azidoquinoline-3-carbaldehyde (1t), a low conversion of this reagent was detected, which can be explained by the fact that 1t tends to exist in the inactive tetrazole form. In addition, our attempt to involve Boc-protected

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

• long carbon chain. Thus far, the structure of compound 8 was identified as shown in Figure 1 and named as kronoponoid B. Of note, the structures of compounds 2–4 are common in plants but rare in animals. Whether these compounds originate from plants or animals so far remains unknown. In addition to the

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• ]. After excitation the electron distribution significantly changes leading to substantial alterations in the chemical behavior of the starting compound. Thereby, UV-induced reactions are a useful addition to common thermal processes. In this regard, photochemical transformations have found wide

• to 2 h did not affect the yield of pyrimidine 9a (Table 1, entry 8). It is important to emphasize that the use of bases essentially impaired the efficiency of the method (Table 1, entries 9 and 10). Apparently, the addition of a basic reagent does not influence the main process and the decrease in

• for the formation of pyrimidines 9 is presented in Scheme 3. At first, intermediate A is formed by Michael addition of cyanamide to enaminone 13. Further elimination of dimethylamine leads to cyanoenaminone B. Next, interaction of the cyano group with dimethylamine results in the formation of

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

• Joydev K. Laha,
• Pankaj Gupta and
• Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

• synthesis of synthetically useful N-arylsulfonylimines from N-(arylsulfonyl)benzylamines using K2S2O8 in the presence of pyridine as a base is reported herein. In addition, a “one-pot” tandem synthesis of pharmaceutically relevant N-heterocycles by the reaction of N-arylsulfonylimines, generated in situ

• their unique stability, defined reactivity, and versatility in organic synthesis [2]. Leveraging their electron-deficient nature, N-arylsulfonylimines are widely used in organic transformations including nucleophilic addition, cycloaddition, imino-aldol reaction, ene reactions, aza-Friedel–Crafts

• synthetic utility of the developed protocol, a tandem “one-pot” synthesis of N-heterocycles was successfully executed (Scheme 3). Thus, exposition of substrates 1 under the optimized reaction conditions followed by the addition of ortho-substituted anilines 3 and K2S2O8 (1 equiv) and heating the reaction

Bromination of endo-7-norbornene derivatives revisited: failure of a computational NMR method in elucidating the configuration of an organic structure

• Demet Demirci Gültekin,
• Arif Daştan,
• Yavuz Taşkesenligil,
• Cavit Kazaz,
• Yunus Zorlu and
• Metin Balci

Beilstein J. Org. Chem. 2023, 19, 764–770, doi:10.3762/bjoc.19.56

• temperatures yielding mixtures of addition products. The structural elucidations of the formed compounds were achieved by NMR spectroscopy. Particularly, the γ-gauche effect and long-range couplings were instrumental in assigning the stereochemistry of the adducts. However, in a recent paper, Novitskiy and

• for those ‘revised structures’ [3]. This paper impelled us to revisit our original work and assess the validity of Novitskiy and Kutateladze’s claim whether our assignment was indeed wrong. Results and Discussion In 2008 we investigated the electrophilic addition of bromine to 1 (7-endo-bicyclo[2.2.1

• ]hept-2-ene) at different temperatures and obtained mixtures of the addition products 2–6 (Scheme 1) [4]. The structures of these compounds 2–6 have been elucidated on the basis of 1H and 13C NMR spectral data, as well as a number of 2D techniques (APT, HETCOR and COSY), and extensive double resonance

Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke–Blackburn–Bienaymé and Ugi reactions

• Oleksandr V. Kolomiiets,
• Alexander V. Tsygankov,
• Maryna N. Kornet,
• Aleksander A. Brazhko,
• Vladimir I. Musatov and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2023, 19, 727–735, doi:10.3762/bjoc.19.53

• structures containing a substituted imidazo[1,2-a]pyridine fragment, such as anticancer [5], antibacterial [6], antifungal [7], antiviral [8], anti-inflammatory [9], antimalarial [10], antiparkinsonian [11] and antituberculous activities [12]. In addition, some derivatives show enzyme inhibition [13] and can

• proved to be inefficient. In addition, we also tested the one-pot method for the synthesis of similar structures [32]. Aminopyridine, aldehyde and Sc(OTf)3 as catalyst were stirred in MeOH/DCM for 45 min at room temperature, then the isocyanide was added and the mixture was stirred for another 8 h

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• resulted in a decreased yield. While fluoro groups were well tolerated, a major drawback of the method is the acid-catalysed dehalogenation of chloro- and bromo-substituted dibenzo[b,f]azepines. The brominated analogue was only isolated in 5% yield, compared to 67% for the unsubstituted 43. In addition

• bromides and electron-withdrawing groups. The authors found that the addition of potassium iodide, and thus in situ palladium-catalysed halogen exchange, improved the yield of dibenzo[b,f]azepine 110. Unsymmetrical derivatives of 110 containing -CO2Me, -CF3, -NO2 and -CN substituents were synthesised in

• , prepared by benzylic bromination of the methyl substituents of 132 and 133 (Scheme 29). 5 1,4-Michael addition Narita et al. [72] reported their total synthesis of bauhinoxepine J (139), a quinone dihydrobenzoxepine derivative, by means of a base-promoted intramolecular etherification (Scheme 30). 6

Synthesis of medium and large phostams, phostones, and phostines

• Jiaxi Xu

Beilstein J. Org. Chem. 2023, 19, 687–699, doi:10.3762/bjoc.19.50

• refluxing toluene under argon atmosphere (Scheme 9) [21]. In addition, the intramolecular coupling reaction of diphenyl pyren-1-ylphosphonate (47) accomplished the synthesis of 3-phenoxybenzo[f]pyreno[1,10-cd][1,2]oxaphosphepine 3-oxide (48) in 35% yield in the presence of largely excessive amounts of AlCl3

• yields with moderate to good diastereoselectivities via Michael addition and nucleophilic addition–elimination (Scheme 17) [39]. The synthesis is a [5 + 2] annulation fashion. The reactions of 2-phenyl/alkoxy-4H-benzo[d][1,3,2]dioxaphosphinin-4-ones 82 and dialkyl 2-benzylidenemalonates 78 produced

• '-carboxylates 83 in 5–10% yield as byproducts. The major products 84 were generated via Michael addition and the nucleophilic addition–elimination of the carbanion of the generated enolate moiety, while the oxyanion of the enolate moiety attacked the phosphorus to form the byproducts 83 (Scheme 18) [40][41

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• –Stephens reaction, method A) and arylacetylenes (Sonogashira reaction, method B). In all cases, even when using a small excess of 8, in addition to the desired monoalkynyl derivative 7, a double alkynylation product 9 was formed (Table 1). The Sonogashira coupling was somewhat more efficient, yielding

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• intermediate for the final product 4a. So, Zn(OAc)2 is crucial in shutting down the formation of 6 by scavenging free bromide in the reaction as ZnBr2 salt (confirmed by HRMS). In addition, an excellent yield of the final product 4a [4a: 94% vs (6, 24% + 3a, 57%)] with additive indicates that zinc acetate

• functionalization at the newly incorporated active methylene center. Cycle-1 is initiated with the reduction of bromomalonate 2a by the photoexcited catalyst PC* to malonyl radical I. This is followed by the Minisci-type addition of radical I to the imidazopyridine, preactivated by Lewis acidic Zn(OAc)2 [29]. PC

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• oriented. In addition, the cross-peaks between H-5/H-9, H-5/H-7α and H-7α/H3-17 suggested H3-17 to be α-oriented. Comparison of the specific rotation was used to establish the absolute configuration of 1. The specific rotation of 1 ( −22 (c 0.01, MeOH)) was similar to the reported data of 2 ( −36 (c 0.01

• , MeOH); lit. −44 (c 0.05, MeOH)) [18], confirming the same absolute configuration these compounds should be derived from the same biosynthetic pathway. In addition, the ECD spectra of (5S,8R,9S,10R,14S)-1 and its enantiomer were calculated at the B3LYP functional using a TD–DFT method [19]. As

• unsaturation required the presence of two heterocyclic rings in the molecule. The presence of an ester carbonyl signal (δC 167.0) and a deshielded oxygenated carbon resonance at C-12′ (δC 104.1) implied the formation of six-membered ring via an ester bond between C-16 and C-12′. In addition, an epoxide moiety

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• anticonvulsant agents had been developed based on PBTA derivatives (Figure 1) [2]. In addition, series of PBTAs (Figure 1) were found to exhibit antibacterial, antifungal, antioxidant, and cytotoxic activities [3][4]. Several strategies have been developed for the synthesis of PBTA derivatives [2][3][4][5][6][7

• brought in by a bulky isopropyl substituent in alcohol 2b. In addition, in all studied cases we observed that the reaction of APBTTs 1 with alcohols 2 always afforded labile side-products 5 (Scheme 9). Compounds 5 were formed when the nucleophile 2 attacked on the position C3a of the substrates 1. Such a

• direction of nucleophilic addition of alcohols to FPD species was observed earlier on the example of 5-oxa-FPDs II and was found to be reversible [33][53][54]. We isolated products 5a,b,e to study their chemical behavior in solutions. We found that when compounds 5a,b,e were dissolved in anhydrous solvents

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• in the presence of TBTQ-C6 was greatly improved. In addition, the fluorescence of CS-TPE was significantly enhanced by introducing TBTQ-C6, and remained relatively stable with variations in pH for both CS-TPE and TBTQ-C6/CS-TPE. Such pH-responsive supramolecular spherical nanoparticles with stable

• addition, the presence of TBTQ-C6 greatly enhanced the fluorescence emission of the nanoparticles and was able to maintain the fluorescence relatively stable at different pH values. Essentially, this work demonstrates the first study involving stimuli-responsive supramolecular polymeric nanoparticles based

• higher-order complexes between TBTQ-C6 and CS-TPE-2% with a tendency toward polymeric supra-amphiphilic assembly. The subsequent increase in transmittance upon addition of an excess of CS-TPE-2% was probably caused by the breakdown of the supra-amphiphilic assembly. The transmittance reached its lowest

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

• years of development. The effort of our group to broaden possibilities to engage metal enolates in reactions with new electrophiles is described. The material is divided according to the organometallic reagent employed in the conjugate addition step, and thus to the particular metal enolate formed

• . Short information on applications in total synthesis is also given. Keywords: asymmetric catalysis; conjugate addition; electrophile; enolate; tandem reaction; Introduction The formation of complex chiral molecules is a crucial task of organic synthesis that enables the synthesis of pharmaceuticals

• α,β-unsaturated carbonyl compounds [2]. In particular, the last-mentioned method is highly synthetically relevant. This approach has the advantage of being more selective and affording more molecular complexity in one step. In addition, transition-metal catalysis allows the introduction of

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• using a laboratory-built pulsed-flow system to save reagents. The optimized conditions in this pulsed-flow mode were then successfully transferred to a continuous flow reactor. In addition, the versatility of this continuous flow device allowed both steps of the reaction to be carried out, namely the

• processes rely on the use of a homogeneous metal catalyst at elevated temperatures necessary to cleave the C3–H bond by oxidative addition. These experimental conditions, easily used in the laboratory, are potentially problematic for scale-up due to efficiency and safety issues (related to the high

• reaction conditions while providing products in shorter reaction times. In addition, the ability to couple multiple reactors with a flow apparatus could also enable us to perform these functionalizations directly from furfural by forming the imine in a first reactor. It should be noted that, in batch, in

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• , Table 1). Control experiments were conducted to obtain more mechanistic clues (entries 2–5, Table 1). An experiment revealed how the exclusion of light completely suppressed the process, therefore establishing the photochemical nature of the transformation (entry 2, Table 1). In addition, we confirmed

• column chromatography, we decided to keep optimizing the transformation using the stoichiometric ratio indicated in entry 13 of Table 1. Importantly, product 3a was obtained in excellent yield (95%) using 1.5 equivalents of DABCO (entry 14, Table 1). In addition, the use of hexane as solvent provided the

• observed that the addition of DABCO to the solution of 2a induced a bathochromic shift of the absorption spectrum towards the visible region, thus indicating the formation of an EDA complex between these chemical species. Importantly, we also confirmed that indole 1a and 2a do not form a photoactive EDA

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• as the starting platform for the modification of an amino acid moiety by nucleophilic substitution and addition reactions, including electrochemically induced processes [5][16][17][18][31]. The electrochemical behavior of the new complexes was investigated to get an experimental support for their

• techniques; for details, see Supporting Information File 1); [α]D20 = 2127 (MeOH). To test the stereocontrolling efficiency of the new ligand L7 and to obtain new cysteine Ni–Schiff base derivatives (RCysNi)L7 which are of practical interest, complex (ΔAlaNi)L7 was involved in a nucleophilic addition as

• (RCysNi)L7 formed in the Michael addition reaction was confirmed using the NOESY spectrum. It is illustrated in Figure 1 for (oBrCysNi)L7 complex as the representative example. A correlation between the signal of the H-2 proton at the α-amino acid stereocenter with the signal of the ortho-protons of the

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• a pH-dependent excimer formation that is significantly red-shifted relative to the pyrene and phenanthridine fluorescence. While the conjugate with a short linker showed negligible spectrophotometric changes due to the polynucleotide addition, the conjugate with a longer and more flexible linker

• fluorescence change upon the addition of ct-DNA also at pH 7 (Figures S13 and S14, Supporting Information File 1), while for Phen-Py-1, more notable fluorescence changes at pH 7 (neutral form) were observed. Therefore, all further studies were performed at pH 7. Thermal melting studies Binding of small

• addition of ct-DNA to a Phen-Py-1 solution resulted in a hypochromic effect in the region 325–365 nm (Figure 3) without a shift of absorption maxima. Systematic deviation of the isosbestic points around 300 nm revealed the coexistence of more than two spectroscopically active species and more than one

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• ). In addition, few examples of difluoromethylphosphonate containing cyclopropanes have been reported to date. These compounds were synthesized either by cyclopropanation of CF2P(O)(OEt)2-containing alkenoates using a Corey–Chaykovsky reagent (sulfaniumyl or oxosulfaniumyl methanides) and diazomethane

• % yield (Table 1, entry 6). In addition, in a catalyst-free reaction under UV irradiation, no reaction occurred and the starting diazo compound 5 was recovered (Table 1, entry 7). Having identified the optimal catalyst and conditions, we then examined the scope of the cyclopropanation reaction by reacting

• amino group to the copper centre of an intermediately produced metallocarbene, thus favouring the formation of one diastereoisomer of 7g [50]. In addition, the cyclopropanes 7a–g were always obtained as mixtures of two diastereoisomers in different ratios and all attempts to separate them using column

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

• undergoing reductive elimination to afford to [2 + 2] adduct, β-oxygen elimination followed by E/Z isomerization and intramolecular lactonization generates the annulated coumarin scaffold. In 2003, the Cheng lab extended on this Ni-catalyzed ring-opening strategy [31]. It was noted the addition of 1.5

• arnottianum Maxim which possesses some antibiotic properties [34]. Mechanistically, the authors proposed the reaction begins with the in situ reduction of Ni(II) to Ni(0) by zinc to generate Ni(0) which undergoes oxidative addition with the organo iodide to yield Ni(II) intermediate 11. Coordination of 11 to

• -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