Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• (CV) was performed using a three-electrode configuration consisting of a glassy carbon macrodisk working electrode (GCE) (diameter of 3 mm; BASi, Indiana, U.S.A.) combined with a Pt wire counter electrode (99.99%; GoodFellow, Cambridge, U.K.) and an Ag wire pseudoreference electrode (99.99

Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• effect. The single crystal structure of compound 3a was determined by X-ray crystallographic diffraction (Figure 1). From Figure 1 it can be seen that the two scaffolds of oxindole at neighboring positions are in trans-configuration. The ethoxycarbonyl group is also in trans-position to the carbonyl

• group in the neighboring oxindole scaffold. Therefore, it can be concluded that the obtained dispiro compounds 3a–m have this kind of relative configuration on the basis of 1H NMR spectra and crystal structure determination. It should be pointed out that ammonium acetate was employed as nitrogen source

• is largely general. The 1H NMR spectra of the obtained compounds 4j–p clearly show similar chemical shifts of the characteristic groups as the spiro compounds 4a–i. Therefore, it can be concluded that the spiro compounds 4j–p have the same relative configuration as the spiro compounds 4a–i. In order

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

• positions were notably confirmed to be at C-3 and C-21, respectively. The ᴅ-configuration of the β-glucopyranosyl unit was assumed to be the one found in related fungal lanostanosides namely; ganosinoside A from Ganoderma sinense [26], fomitosides I and J from Fomitopsis pinicola [34]. Concerning the

• configuration at C-3', it was assigned as S by careful comparison of the 1H and 13C NMR data of compound 1 with those of related lanostane derivatives comprising the 3-hydroxy-3-methylglutaryl moiety produced by some fungi including Fomitopsis pinicola [23], Piptoporus betulinus [13], and Pholiota populnea [35

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

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• the correlation of H3-15/H2-6 (Figure 3), which results in ambiguity in the relative configuration assignment of 1. Thus, NMR chemical shift calculations and ECD calculations were used to confirm the relative and absolute configuration of 1. More specifically, NMR calculations were carried out at the

• calculations. The CD spectrum matched well with the calculated ECD spectrum of 1a (Figure 4), revealing the absolute configuration of 1 to be 7R,10S, and it was named aquisinenoid F. Compound 2 was isolated as pale yellow gum, and was assigned the molecular formula C15H24O2 as inferred from the HRESIMS m/z

• planer structure of 2 was obtained (Figure 1). The relative configuration of 2 was established by careful interpretation of the ROESY correlations (Figure 3). The ROESY correlations of H-8/H3-15 and Ha-6/H3-15 and the coupling constant of H-7 (JH-7, Ha-6 = 3.8 Hz) suggest the relative configurations (7S

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

• Xiu-Yu Chen,
• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• a high diastereoselectivity. From Figure 1, it can be seen that the three protons and the phenyl group have cis-configuration in the hexahydro-1,6-naphthyridyl ring. During the investigation of the above three-component reaction, we found that the three-component reaction of isoquinoline, dimethyl

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• substituent at C-2 of the phenol moiety. The final carbon atom at 171.9 ppm (C-15) could be attributed to a carboxylic acid function with HMBC correlations from H-13 and H-14, thereby completing the determination of the planar structure of 1. To determine the configuration of 1, we measured its optical

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• the construction of a range of δ-olefin-containing aliphatic nitriles with (E)-configuration selectivity. This new method features wide substrate scope, mild conditions, and direct N–O activation. Keywords: direct N–O activation; E-selectivity; nitrile synthesis; ring-opening cross-coupling; sulfuryl

• -containing aliphatic nitriles possess E-configuration at the double bond. This transformation could be easily activated by SO2F2 in situ without the need of pre-introduction of electrophores. Representative nitrile-containing functional materials, drug carriers, and medicines. Activating protocol of

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

• , the configuration at the position C-3 is determined by the chiral ligand L1 and was determined previously as (R) [19]. To gain insight into the reactivity of enolates formed in this transformation, we evaluated properties of Zn enolates by DFT calculations (Figure 2). The corresponding (E) and (Z

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

• configuration of the products by modifying the substituents on the nitrogen of the pyridinium salts. Further, the method showed a wide substrate scope for both the Z- and E-alkenylated products in which Z-selectivity was achieved when N-methylpyridinium salts were used and E-selectivity when N-benzylpyridinium

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

• relative configuration of the cyclohexanone segment in 1. The small coupling constant (J3,4 = 3.0 Hz) indicated that H-3 and H-4 are on the same side of the ring, corroborated by the literature [18]. The absolute configuration of compound 1 was identified as 3R,4R in accordance with the experimental and

• compound 4. According to the literature [22], the absolute configuration at C-2 for 4 was assigned as S, from the Cotton effects in its ECD curve (Figure S26 in Supporting Information File 1) [283 nm (Δε −0.71)]. The absolute configuration of 4 was determined as 2S,2″R based on the comparison of the

• configuration was E. However, the overlapping signals of H2-5 and H2-8 made it difficult to determine the geometry of the ∆6,7 in the same manner. By comparing the 1H and 13C chemical shifts with those of similar compounds [24][25][26][27][28], the geometry of the ∆6,7 was determined to be E. The configuration

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

• configuration in a molecule, in short, it is the single most important spectroscopic tool aside from X-ray crystallography to provide an accurate ensemble-guided view of the structure, even conformational dynamics in a molecule. Quantum mechanical/nuclear magnetic resonance (NMR) approaches are used for the

• experiments. The aforementioned authors, Novitskiy and Kutateladze, however, claimed in their paper [3] that the assigned configuration of product 6 was wrong. They revised the structure 6 to an isomeric symmetric anti-7-bis-exo-tribromide 7 (Figure 1). Below, we will briefly discuss how we initially

• elucidated the exact configuration of compound 6. The symmetrical structure of 6 could be characterized easily because of its four-line 13C NMR spectrum. However, on the basis of 13C NMR data alone we were not able to distinguish between possible symmetrical tribromides. The configurations of the bromine

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

• nanoribbon is 4.3 nm in length, with an end-to-end twist of 117° as indicated by single-crystal X-ray diffraction. Except for the helical conformation, two other isomers, in the waggling or mixed configuration were also generated in the last oxidative cyclodehydrogenation step, and they could be separated

• = 844 000 M−1 cm−1 at 573 nm). A pair of enantiomers, (M,M)- and (P,P)-configuration was revealed by single crystal X-ray diffraction and optically pure samples of 125 were isolated by chiral HPLC. Meanwhile, a record high electronic circular dichroism (ECD) signal in the visible spectral range (Δε

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

• -17 and C-14 as well as the appearance of the H3-17 as a singlet signal confirmed the connection of a hydroxy group at C-14. The relative configuration of 1 was characterized by NOESY spectra. In the NOESY experiment (Figure 3), the cross-peak between H-8 and H3-20 suggested these protons to be syn

• 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

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

• NMR experiments (Hα coupling constants ≈ 6.4–8.6 Hz), the high level of diastereocontrol can be associated with the preferred Z-configuration of the cyclic copper enolate intermediate. In the presence of the chiral ligand (R,S)-L17, the tandem reaction was accomplished in a highly enantioselective way

• Indonesian sponge Haliclona sp. [108]. Their synthesis takes advantage of the same tandem procedure that gives β-ketoester 219. The asymmetric conjugate 1,4-addition and subsequent acylation provided good stereocontrol and the authors could revise the thus far incorrectly assigned configuration of the target

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

• exceeding 10 bar. Hence, we worked at about 7.5 bar to stay below the boiling curve of toluene in the temperature range used (180–200 °C). The first experiments performed with this configuration allowed us to validate our hypothesis, namely the possibility of directly functionalizing furfural by forming the

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

• (with ʟ-configuration at the α-stereocenter) was obtained in quantitative yield with high diastereselectivity (83% de). Previously, the same protocol was applied to the parent Belokon complex, affording the corresponding serine derivative in 97% yield with 81% de [32]. For spectral characterization of

• yields and with excellent stereoselectivity: only traces of the ᴅ-cysteine derivatives were determined, demonstrating the advantages of the tert-butyl-containing template (for the probable reasons, see below). The relative ʟ-configuration of the amino acid α-stereocenter in the major diastereomers of

• benzyl fragment was observed. This indicated that H-2 is located on the same side of the nickel coordination plane as the benzyl substituent at the proline nitrogen atom, leading to the ʟ-configuration of the α-amino acid stereocenter. Notably, the major stereoisomer of all thiolated compounds (RCysNi)L7

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

• symmetrical sandwich configuration as optimal for the largest exciton splitting, while other reports suggested a favored orientation with one aromatic moiety displaced (ca 1.4 Å) from the other to minimize van der Waals repulsion [30]. Redistribution of charges at acidic pH (protonated phenanthridine nitrogen

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

• diastereoisomer adopts trans configuration (Figure 1). Furthermore, terminal aliphatic alkenes as well as N-Boc-allylamine were subjected to [2 + 1] cycloaddition reactions with the carbene precursor 5. The results are summarized in Scheme 4. As observed, the procedure was successful with a series of terminal

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

• -induction of the aldol stereocenter by β-alkoxy ketone 9, leading to an (S)-configuration [18][19][20]. This control is supposed to follow a boat transition state A stabilized by a formyl hydrogen bond [30]. It is known to be dependent on the nature of the β-alkoxy substituent, being particularly favoured

• by the PMB and other aromatic groups, while being disfavoured by silyl protecting groups. Alternatively, an (R)-configuration of C-15 could result from a polar Felkin–Anh model controlled by aldehyde 8 through chair-transition state B [14][15][16]. To determine the configuration of C-15, we initially

• proceeded through a 1,5-anti induction by the ketone to form 21. Most importantly, compounds 22–25 bear the (11R,13R) configuration of latrunculins (1 and 2). Conclusion A straightforward synthesis of a stereopentade intermediate towards latrunculins and lactol-opened analogues was achieved with high

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• ][17] by analysis of NMR and mass spectra and confirmed by X-ray crystallography in an initial report. However, attempts to determine the absolute configuration of the epoxide present in compound 1 based on crystallographic data were unsuccessful. By matching the sign of the Cotton effect curves

• combretastatin D-1 (1) in 23% overall yield after 16 steps. Later, the same authors performed the enantioselective synthesis of 1 in an attempt to review its absolute configuration [41]. Thus, acetylation of compound 2 followed by the use of Jacobsen’s catalyst [42] to perform the epoxidation of the double bond

• ) was different from the value reported for the natural product ([α]D −100, c 0.015, CHCl3) [16] and hypothesized that the configuration of the natural compound would be 3S,4R, different from that reported in the Pettit previous work. Couladouros and co-workers based the synthetic design of

Synthesis, α-mannosidase inhibition studies and molecular modeling of 1,4-imino-ᴅ-lyxitols and their C-5-altered N-arylalkyl derivatives

• Martin Kalník,
• Sergej Šesták,
• Juraj Kóňa,
• Maroš Bella and
• Monika Poláková

Beilstein J. Org. Chem. 2023, 19, 282–293, doi:10.3762/bjoc.19.24

• ᴅ-lyxo-configuration and bearing a free endocyclic nitrogen resulted in micromolar GMII inhibitors. In addition, their potency toward GMII was found to be 2.4–3.8 times lower than toward Drosophila melanogaster α-mannosidase dGMII (dGMII) [26]. The incorporation of an N-acyl aminomethyl group onto C

• hydrolysis of the isopropylidene moiety provided the desired derivatives 17–19. The hydrochloride salt of the free iminosugar 20 was obtained from N-benzyl derivative 17 under the same reaction conditions as described for the hydrochloride 10. Next, the configuration at the C-5 stereocenter in 13 was

• -arylalkylated iminosugars 26–28, the naphthyl derivative 28 showed the strongest activity against AMAN-2 (Ki = 18 μM) and a selectivity similar to the p-iodobenzyl analog 27. These findings suggest that both the C-5 hydroxy group and R-configuration at the corresponding carbon are necessary for retaining the

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

• precursor towards the tetrahydrofuran-ring formation. The intramolecular atom-transfer radical cyclization was thus carried out with achiral di-tert-butylbipyridine-ligated CuI 171 to generate the [5-8-5] scaffold 172 in 55% yield, while securing the C10 stereocenter in the required configuration and

An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies

• Tharun K. Kotammagari,
• Sweta Misra,
• Sayantan Paul,
• Sunita Kunte,
• Rajesh G. Gonnade,
• Manas K. Santra and
• Asish K. Bhattacharya

Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19

• configuration of each enantiomer was determined by single-crystal X-ray analysis. In addition, a one-pot synthesis of (±)-incarviditone has been achieved from rac-rengyolone by using KHMDS as a base. We have also assessed the anticancer activity of all the synthesized compounds in breast cancer cells

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

• references. Keywords: biosynthesis; configuration determination; germacrene B; structure elucidation; terpenes; Introduction Terpenoids constitute the largest class of natural products with ca. 100,000 known compounds. Biosynthetically, all terpenoids are derived from only a few acyclic precursors

• -cyclisation to the (Z,E)-germacradienyl cation (E) or a 1,11-cyclisation to the (Z,E)-humulyl cation (F), the E/Z stereoisomers of B and C. Furthermore, a 1,6-cyclisation to the bisabolyl cation (G) or a 1,7-cyclisation to H may follow, which is not possible from A because of its 2E configuration (a

• hypothetical (E)-cyclohexene or (E)-cycloheptene would be too strained, the smallest possible ring with an E configuration is (E)-cyclooctene). In some cases the initially formed neutral product can become reprotonated to initiate a second round of cyclisation reactions which usually leads to compounds of