Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• agreement with those reported by others [20][21][22]. This compound was erroneously assigned as 3α-bromocholest-5-ene [10]. The major, slightly more polar product of the Appel reaction was 3β-bromocholest-5-ene (4, Figure 4). It crystallized as colorless plates, and the structural and stereochemical

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• -heterocycles [39][40][41][42][43][44][45] and specifically α-methylene-γ-lactams as a subset of this compound class, are popular targets in heterocyclic chemistry and drug discovery [46][47][48][49][50][51][52][53][54][55][56]. Against this background, we herein disclose a full account of our studies on the

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

• actual use of this compound requires a fairly extraordinary experimental setup [52][53]. An additional issue with PH3 involves the choice of using the gas-phase or liquid-phase experimental chemical shifts, which differ dramatically: the universally used value for the gas-phase chemical shift is −266.1

• supported by the amide-like CO infrared stretching frequency of 1654 cm−1. This compound further warrants mention since one might suppose that the carbonyl carbon atom would be found near 170 ppm in the 13C NMR spectrum by analogy to amides, but was instead observed at 228 ppm and confirmed by a calculated

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B

• Adwoa P. Nartey,
• Aboagye K. Dofuor,
• Kofi B. A. Owusu,
• Anil S. Camas,
• Hai Deng,
• Marcel Jaspars and
• Kwaku Kyeremeh

Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185

• , and SrfAD on the surfactin synthetase complex [23][24]. We hope to confirm this similarity in the near future as we proceed to further study the whole genome sequence of strain DE2B. Subsequently, using the fully elucidated structure of compound 1, we noticed that this compound was part of a

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• Axinyssa sp. along with the structurally related compound halichonic acid B ((+)-2) [5]. Structurally, (+)-2 is a pipecolic acid derivative containing a cyclohexenyl ring as a substituent group. This compound also features four stereogenic centers (three of which are located within the piperidine ring) and

• , antifungal, and antimicrobial properties [10][19][20][21][22]. Notably, (+)-4 was also co-isolated with compounds (+)-1 and (+)-2 in sponge extracts, suggesting that these compounds may share a common biosynthetic pathway [4][5]. Both enantiomers of 4 have been previously synthesized [9][23][24], and this

• compound has also been prepared in racemic form [25]. To supply the final two carbon atoms found in the halichonic acids, amine 4 was condensed with a solution of ethyl glyoxylate in toluene, giving imine 7 in 95% yield. We found that imine 7 could be purified by column chromatography on silica gel if the

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• this compound was not isolated and identified. Carrying out the same reaction with 1.5 M DIBAL gave complete conversion to 8 (Table 1, entry 2). The formation of 8 from 7 is surprising because it contrasts the complete lack of reaction of fully DCB protected 1 with DIBAL [15]. It means that the

Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• the past 5 years, the NatureBank open access compound library currently contains only ≈100 pure natural products. In an effort to expand this compound library, we have recently embarked on a program whereby a subset of the NatureBank marine and terrestrial extracts have been analysed by UHPLC–MS in

New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling

• Elenilson F. da Silva,
• Krist Helen Antunes Fernandes,
• Denise Diedrich,
• Jessica Gotardi,
• Marcia Silvana Freire Franco,
• Carlos Henrique Tomich de Paula da Silva,
• Ana Paula Duarte de Souza and
• Simone Cristina Baggio Gnoatto

Beilstein J. Org. Chem. 2022, 18, 1524–1531, doi:10.3762/bjoc.18.161

• relied on a comparison of compound 8 with crystallographic ligands of IMPDH, on the basis that it would represent a secure interpretation of the site interactions similarity with inhibitors, thus, suggesting that this compound acts by the same mechanism. Therein, flexible docking for compound 8 to the

Sinensiols H–J, three new lignan derivatives from Selaginella sinensis (Desv.) Spring

• Qinfeng Zhu,
• Beibei Gao,
• Qian Chen,
• Tiantian Luo,
• Guobo Xu and
• Shanggao Liao

Beilstein J. Org. Chem. 2022, 18, 1410–1415, doi:10.3762/bjoc.18.146

• ) suggested that 3 was possibly a racemic mixture. Enantioseparation of 3 by HPLC using a chiral-pak IA column provided the enantiomers with a ratio about 3:2 (Figure S28, Supporting Information File 1) suggested its mixture feature. Unfortunately, the limited amount available of this compound did not allow

Preparation of an advanced intermediate for the synthesis of leustroducsins and phoslactomycins by heterocycloaddition

• Anaïs Rousseau,
• Guillaume Vincent and
• Cyrille Kouklovsky

Beilstein J. Org. Chem. 2022, 18, 1385–1395, doi:10.3762/bjoc.18.143

• ) ppm; 13C NMR (90 MHz, CDCl3) δ 162.5, 148.8, 120.3, 77.4, 76.6, 70.7, 38.7, 22.6, 10.9 ppm; HRMS (m/z): [M + Na]+ calcd 173.0573; found, 173.0572; [α]D20 +132.0 (c 1.0, CH2Cl2). (2R,3S,6RS)-3-Ethyl-2-ethynyl-6-methoxy-3,6-dihydro-2H-pyran (19): This compound was prepared according to reference [18]. A

• pressure. Purification by column chromatography (5% Et2O/pentane), gave 19 as a colourless oil (866 mg, 94%, 91/9 mixture of stereoisomers). Analytical data were in agreement with literature data [18]. (2R,3S,6RS)-3-Ethyl-2-((E)-2-iodovinyl)-6-methoxy-3,6-dihydro-2H-pyran (20): This compound was prepared

On drug discovery against infectious diseases and academic medicinal chemistry contributions

• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 1355–1378, doi:10.3762/bjoc.18.141

• -bearing substances, endowed with an antibacterial effect [58]. However, this compound was originally patented for a fungicide effect [59] and then found to also inhibit mammalian c-Jun N-terminal kinase [60]. Unsurprisingly, it was also reported in 2022 as a covalent inhibitor for the SARS-CoV-2 main

• the virus protease binding the non-covalent inhibitor X77 (2). Of importance is that this compound derives from inhibitors of SARS-CoV-1 main protease, such as 4 and 5, which were found in 2013 [79][80]. Interestingly, this truly large virtual screening came out with (only) three validated hits

• second original class of bacterial gyrases inhibitors. In 2004, the nitro-bearing derivative 11, resulting from a high-throughput phenotypic-based screening, was patented by Pharmacia/Pfizer for its antibacterial properties [122][123]. Even if this compound was also effective in vivo, many synthesis and

Computational model predicts protein binding sites of a luminescent ligand equipped with guanidiniocarbonyl-pyrrole groups

• Neda Rafieiolhosseini,
• Matthias Killa,
• Thorben Neumann,
• Niklas Tötsch,
• Jean-Noël Grad,
• Alexander Höing,
• Thies Dirksmeyer,
• Jochen Niemeyer,
• Christian Ottmann,
• Shirley K. Knauer,
• Michael Giese,
• Jens Voskuhl and
• Daniel Hoffmann

Beilstein J. Org. Chem. 2022, 18, 1322–1331, doi:10.3762/bjoc.18.137

• , Figures S22–S25). This compound 1 was tested in initial binding assays using fluorescence emission as well as native gel electrophoresis. We could indeed show that 1 binds to 14-3-3ζ as detected by native gel electrophoresis and fluorescence titration (Supporting Information File 1). Experiments show that

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• ). The presence of the DPA group in DiKTa-DPA-OBuIm transforms this compound from one that is MR-TADF to one that is better described as a donor–acceptor TADF, which is reflected in the red-shifted and broadened emission [28]. Results and Discussion DiKTa-OBuIm was obtained in three steps (Scheme 1) in

• same at 0.27 eV. The nature of S1 and T1 resemble to those of its parent DiKTa and so this compound is likely to behave as a MR-TADF emitter. The nature of the S2 state is n–π* in DiKTa-OMe. The excited state picture of DiKTa-DPA-OMe is different to that of other reported D–A-type systems containing

Enantioselective total synthesis of putative dihydrorosefuran, a monoterpene with an unique 2,5-dihydrofuran structure

• Irene Torres-García,
• Josefa L. López-Martínez,
• Rocío López-Domene,
• Manuel Muñoz-Dorado,
• Ignacio Rodríguez-García and
• Miriam Álvarez-Corral

Beilstein J. Org. Chem. 2022, 18, 1264–1269, doi:10.3762/bjoc.18.132

• signals of the oxygenated carbons (C2 and C5). The same behavior pattern can be observed in the 1H NMR data. This made us think that the natural product of T. mendocina could have an acyclic skeleton instead of a dihydrofuran one. For this reason, we propose this compound should be the diol called

Synthesis of tryptophan-dehydrobutyrine diketopiperazine and biological activity of hangtaimycin and its co-metabolites

• Houchao Xu,
• Anne Wochele,
• Minghe Luo,
• Gregor Schnakenburg,
• Yuhui Sun,
• Heike Brötz-Oesterhelt and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1159–1165, doi:10.3762/bjoc.18.120

• temperature. Also the addition of base (NEt3) did not promote the reaction. Therefore, the mode of action of TDD towards glutathione S-transferase needs further investigation. Conclusion We have established an efficient synthesis of TDD that makes this compound available from ʟ-tryptophan with a high yield of

Facile and diastereoselective arylation of the privileged 1,4-dihydroisoquinolin-3(2H)-one scaffold

• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1070–1078, doi:10.3762/bjoc.18.109

• % at 30 μM concentration. Dose–response testing of this compound against both NCI-H460 and A549 lung carcinoma cell lines resulted in the determination of IC50 values for compound 9j as 31.4 ± 0.48 μM and 13.6 ± 3.34 μM, respectively (see Supporting Information File 1 for details). Conclusion In

Synthesis of α-(perfluoroalkylsulfonyl)propiophenones: a new set of reagents for the light-mediated perfluoroalkylation of aromatics

• Durbis J. Castillo-Pazos,
• Juan D. Lasso and
• Chao-Jun Li

Beilstein J. Org. Chem. 2022, 18, 788–795, doi:10.3762/bjoc.18.79

• obtain the corresponding sulfinate in limited yield, the decomposition of this compound after several days at 4 °C, and within a few minutes under heating deemed its applicability impractical. After this first step, we proceeded to test the nucleophilic substitution between our perfluoroalkylsulfinate

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• ] and Domingo [48], we calculated global electrophilicity indexes (GEI, ω) for both PRP (1) and cyclopropenes 2 to determine which type of electron demand takes place during cycloaddition reactions. The global value of the electrophilicity index for azomethine ylide 1 (1.29 eV) revealed that this

• compound displays a moderate electrophilicity (Table 2, entry 1). By comparing the global electrophilicity indexes of reactants 1, 2a–p (Table 2, entries 1–17), we concluded that the cyclopropene cycloadditions to PRP (1) appear to be inverse electron demand (IED) reactions, i.e., they can be considered as

Tri(n-butyl)phosphine-promoted domino reaction for the efficient construction of spiro[cyclohexane-1,3'-indolines] and spiro[indoline-3,2'-furan-3',3''-indolines]

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

Beilstein J. Org. Chem. 2022, 18, 669–679, doi:10.3762/bjoc.18.68

• reaction, the nucleophilic addition of the zwitterion (A) to this compound takes place at the exocyclic position giving the adduct (E), which in turn proceeds with the intermediates (F) and (G) according to the above mentioned similar processes to give the spiro compound 5. The different addition direction

New synthesis of a late-stage tetracyclic key intermediate of lumateperone

• Mátyás Milen,
• Bálint Nyulasi,
• Tamás Nagy,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2022, 18, 653–659, doi:10.3762/bjoc.18.66

• in various ways (we only show here the path that seems the most advantageous). According to this, compound 17 was N-alkylated at the indoline nitrogen atom with N-methylchloroacetamide to give 18, then cyclized in one pot to derivative 8. Alternate methods for the 17→8 transformation require more

Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• -b]furan-2-one, has been recently identified as an extremely efficient neuroprotective butenolide. Herein, we report the targeted synthesis of this compound as well as new synthetic protocols toward a class of compounds derived from 2H-furo[2,3-c]pyran-2-ones (karrikins) via bioisosteric exchange of

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• menadione, a synthetic naphthoquinone belonging to the vitamin K group. This compound can be synthesized by different methods and it has a broad range of biological and synthetic applications, which will be highlighted in this review. Keywords: cancer; chemical reactions; 2-methyl-1,4-naphthoquinone

Synthesis and late stage modifications of Cyl derivatives

• Phil Servatius and
• Uli Kazmaier

Beilstein J. Org. Chem. 2022, 18, 174–181, doi:10.3762/bjoc.18.19

• , non-proteinogenic amino acid (2S,9S)-2-amino-9,10-epoxy-8-oxodecanoic acid (Aoe) as a zinc-binding group. Interestingly, Aoe with its α-epoxyketone motif is wide-spread among this compound class as it is present in other natural products such as Cyl-1 and Cyl-2 [16][17], chlamydocin [18], and many

• ozonide formed during the reaction [57]. Consequently, no PPh3 or Me2S was required to obtain the crude aldehyde. Subsequent addition of a Wittig ylide gave access to a cyclopeptide with an α,β-unsaturated ester side chain as a (E/Z) mixture. Unfortunately, this compound contained triphenylphosphine oxide

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• ], which further increases the importance of this compound class. Much work has been dedicated to the synthesis of 1,4-DHPs, but in most of these reports, the DHP ring is fully substituted. There are only few methods available for the synthesis of C5–C6-unsubstituted 1,4-DHPs. The presence of an

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• -naphthoquinone-4-sulfonic acid sodium salt (β-NQSNa, 18) was very effective as a colorimetric indicator of blood amino acids. This compound came to be called Folin's reagent. To achieve 18 with adequate purity to be used in the tests, an elaborate large-scale synthetic route was developed. β-Naphthol (20) was

• enzyme human carboxylesterase (hCE1) that cleaves carboxylic esters. This enzyme functions in the detoxification metabolism of carcinogenic and mutagenic organic compounds, converting them into nontoxic metabolites. This compound served as inspiration for Hatfield and co-workers [84], who proposed the

• acid at room temperature produces azepinedione 40 in an 82% yield. This compound can be transformed into several 3-substituted and 4-hydroxy derivatives. However, an interesting transformation results from the treatment of 40 with hot aqueous sodium hydroxide, resulting in 2-oxoquinoline 41 in an 80