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

• , selective, and potent anti-HIV activity, however, it failed in phase IIb clinical trials due to viral resistance [28][29][30][31]. Even so, this class of natural products has great antiviral potential and its chemical modification could lead to new, efficient, and safe therapeutic resources. In this

Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase

• Sanaz Ahmadipour,
• Alice J. C. Wahart,
• Jonathan P. Dolan,
• Laura Beswick,
• Chris S. Hawes,
• Robert A. Field and
• Gavin J. Miller

Beilstein J. Org. Chem. 2022, 18, 1379–1384, doi:10.3762/bjoc.18.142

• , syntheses of C6-modified mannose 1-phosphates 13 and 17 were developed (Scheme 1). The synthesis of 6-amino-6-deoxymannose 1-phosphate 13 started from protected thioglycoside 10 [6]. A two-step modification using Appel halogenation followed by nucleophilic substitution with azide furnished 11. Conversion of

• synthesis on a preparative scale to yield 19 in milligram quantities and in an isolated yield of 59%. We previously demonstrated the GDP-Man-PP from S. enterica exhibited relaxed specificity towards C4 & C5 pyranose modification, although there is a fine balance to be struck between size and charge when

Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants

• Karan Malhotra and
• Jakob Franke

Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135

• modification of monocyclic marnerol and tricyclic thalianol (12) in Arabidopsis [27][41]. Marneral synthase (MRN1) produces two oxidation products, one is marneral (aldehyde) and the other marnerol (alcohol). Arabidopsis CYP71A16 hydroxylates the allylic methyl side-chain of monocyclic marneral/marnerol to 23

• -hydroxymarneral/23-hydroxymarnerol. Modification of thalianol (12) involves CYPs from two clans. Genes encoding CYP708A2 (clan 85) and CYP705A5 (clan 71) are physically clustered with the thalianol synthase (THAS) gene, encoding the corresponding oxidosqualene cyclase. CYP708A2 oxidises the tricyclic thalianol

Synthesis of protected precursors of chitin oligosaccharides by electrochemical polyglycosylation of thioglycosides

• Md Azadur Rahman,
• Kana Kuroda,
• Hirofumi Endo,
• Norihiko Sasaki,
• Tomoaki Hamada,
• Hiraku Sakai and
• Toshiki Nokami

Beilstein J. Org. Chem. 2022, 18, 1133–1139, doi:10.3762/bjoc.18.117

• . However, a trace amount of 8a was formed together with byproducts, and the recovered amount of tetrasaccharide 4a was 64% (Scheme 1). These results strongly suggested that path a in Figure 7 is the most probable mechanism of the reaction. Modification of electrochemical polyglycosylation protocol The

• , we have developed a practical method to synthesize longer-chain oligosaccharides within a short period of time through electrochemical polyglycosylation. A rational reaction mechanism was proposed based on oxidation potentials of the oligosaccharides, and further modification of the protocol was

Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• nitrogen-enriched quinoxaline-based structures. Literature-known procedures for such a quinoxaline modification starting from tetrazolo[1,5-a]quinoxalines 1 are the synthesis of 1,2,3-triazoloquinoxalines 3 via copper-catalyzed azide–alkyne cycloaddition (CuAAC) [10] and the synthesis of imidazo[1,2-a

• for further modification of the triazoloquinoxalines. For example, the alkyne-bearing compound 14f can be used for further CuAAC reactions and compounds including leaving groups, such as in 14j, can be easily converted by nucleophilic substitutions. In addition, compounds with alkene- (14m) or hydroxy

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• ) probably undergoes rearrangement, decarboxylation, methylation reaction, and further modification to generate compounds 1 and 2. Conclusion S. sp. KIB-H1544 was isolated from the rhizosphere soil of Datura stramonium L. Two novel diarylcyclopentenones daturamycins A and B and one new p-terphenyl

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• ). Different enantiomeric ratios could explain the properties of the active sites in the corresponding terpene synthases, which remain unclear for further investigations [22]. The diversified structures of terpenes were constructed by terpene synthase [26] along with the post-modification enzymes, such as P450

• of the cyclization mechanism and characterization of post-modification enzymes for the biosynthetic pathway of these sesquiterpenoids will provide insights into expanding the chemical space from marine sponges. Experimental General experimental procedure. The melting point was recorded using an SGW X

Efficient production of clerodane and ent-kaurane diterpenes through truncated artificial pathways in Escherichia coli

• Fang-Ru Li,
• Xiaoxu Lin,
• Qian Yang,
• Ning-Hua Tan and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2022, 18, 881–888, doi:10.3762/bjoc.18.89

• cyclase) act on geranylgeranyl diphosphate (GGDP) to perform regio- and stereoselective cyclizations or skeleton rearrangement reactions via carbocation chemistry to form diverse and versatile carbon skeletons; and ii) multiple post-modification enzymes, most often cytochrome P450s, decorate the carbon

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-a]pyridines and terminal alkynes

• Mio Matsumura,
• Kaho Tsukada,
• Kiwa Sugimoto,
• Yuki Murata and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 863–871, doi:10.3762/bjoc.18.87

• groups in many biologically active substances and pharmaceuticals, such as zolpidem, alpidem, and GSK812397 [1][2][3]. Therefore, the development of multiple chemical modification methods, at the 3-position of the imidazo[1,2-a]pyridine skeleton, for the synthesis of 3-substituted-imidazo[1,2-a]pyridines

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• substituents on the benzene rings of B(C6F5)3 is responsible for its stronger Lewis acidity compared to B(C6H5)3, and reacted efficiently with the basic fluorescent materials. In 2011, Hayashi investigated the modification of pyridyl-conjugated polymer films with the Lewis acid BF3 [31]. Through repeated acid

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• optical band gap [18][27][28]. Thus, the combination of molecular structure modification and atom replacement could be a viable strategy, for the precise modulation molecular energy levels and yield molecules with strong application potential in organic functional materials, such as OFETs, and CPLs, among

Identification of the new prenyltransferase Ubi-297 from marine bacteria and elucidation of its substrate specificity

• Jamshid Amiri Moghaddam,
• Huijuan Guo,
• Karsten Willing,
• Thomas Wichard and
• Christine Beemelmanns

Beilstein J. Org. Chem. 2022, 18, 722–731, doi:10.3762/bjoc.18.72

• responsible for the modification of many important signaling molecules that are involved in a wide variety of crucial biological processes, such as cellular respiration, detoxification, and photosynthesis, within almost all living organisms [8]. In general, Ptases can be distinguished by their substrate

A study of the photochemical behavior of terarylenes containing allomaltol and pyrazole fragments

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

Beilstein J. Org. Chem. 2022, 18, 588–596, doi:10.3762/bjoc.18.61

• complex mixture of products. At the same time the blocking of ESIPT-processes by the modification of the hydroxy group allows one to direct the photoreaction exclusively to the pathway of 6π-electrocyclization of the 1,3,5-hexatriene system. Thus, the study of the photochemical properties of similar

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• .18.52 Abstract The interest in organic materials exhibiting thermally activated delayed fluorescence (TADF) significantly increased in recent years owing to their potential application as emitters in highly efficient organic light emitting diodes (OLEDs). Simple modification of the molecular structure

• attached through a phenylene bridge. A modification of the pyrimidine unit with CN, SCH3, and SO2CH3 functional groups at position 2 is shown to enhance the emission yield up to 0.5 with pronounced TADF activity. Keywords: carbazole; pyrimidine; RTP; synthesis; thermally activated delayed fluorescence

• , good electrical and optical properties, and easy chemical modification is a desired structural unit in organic structures targeted for numerous applications including organic photovoltaic solar cells (OPV) [12][13][14], organic field-effect transistors (OFETs) [15][16][17], chemical and biosensors [18

The asymmetric Henry reaction as synthetic tool for the preparation of the drugs linezolid and rivaroxaban

• Martin Vrbický,
• Karel Macek,
• Jaroslav Pochobradský,
• Jan Svoboda,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2022, 18, 438–445, doi:10.3762/bjoc.18.46

• highly efficient catalysts based on copper complexes of different types of chiral ligands, 2-(pyridin-2-yl)imidazolidine-4-ones (I–III), bis-oxazolines (IV–VII), or diamine (VIII) were chosen for the study (Figure 2). Furthermore, the modification of the structure of the prochiral aldehyde intermediates

• 15 and 19 was also performed with the aim to increase the enantiomeric purity of the corresponding nitroaldol products 21–26. The structural modification consisted in the introduction of different alkyl moieties to the carbamate functional group of the aldehyde intermediates 15–20. As bulky and/or

•  2). The bulky (R2 = t-Bu) or chiral (R2 = ʟ-menthyl or (−)-bornyl) alkoxy groups (derived from relatively inexpensive and readily available alcohols) were introduced into the carbamate moiety instead of an ethyl group as in aldehydes 15 and 19. Here, the influence of this structural modification 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

Site-selective reactions mediated by molecular containers

• Rui Wang and
• Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

• powerful role of molecular containers to achieve precise transformation of complex molecules. Oxidation C–H bonds are ubiquitously distributed in nearly all of the organic compounds, which makes them predominant candidates for the modification of complex molecules. Without pre-activation, direct

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• ) [46]. The catalyst was found to be efficient to promote the Sonogashira coupling of arylhalides and phenylacetylene under microwave and conventional heating conditions. Rather than applying a set of reaction conditions, the desired reaction could be achieved by the modification of the catalyst

Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity

• Anna V. Korotina,
• Svetlana G. Tolshchina,
• Rashida I. Ishmetova,
• Natalya P. Evstigneeva,
• Natalya A. Gerasimova,
• Natalya V. Zilberberg,
• Nikolay V. Kungurov,
• Gennady L. Rusinov,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2022, 18, 243–250, doi:10.3762/bjoc.18.29

• to the lack of convenient methods for their synthesis and modification. For example, synthesis and properties of some [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine derivatives are described in the literature [15][16][32][33]. However isomeric [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines are currently unknown

• ). Therefore, the development of methods for the synthesis and modification of new triazolo[1,5-b][1,2,4,5]tetrazines can be considered as an attractive task for heterocyclic and medicinal chemistry. Results and Discussion In this work, the synthesis of [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines has been

• derivative 3b proved to be a moderately active (MIC = 6.25 μg/mL) in relation to Trichophyton violaceum and Epidermophyton floccosum. In case of pyrazolyl derivative 3g, a high fungistatic activity (MIC = 1.5 μg/mL) was detected for the Epidermophyton floccosum strain. Modification of active compounds 3a,b

Anomeric 1,2,3-triazole-linked sialic acid derivatives show selective inhibition towards a bacterial neuraminidase over a trypanosome trans-sialidase

• Peterson de Andrade,
• Sanaz Ahmadipour and
• Robert A. Field

Beilstein J. Org. Chem. 2022, 18, 208–216, doi:10.3762/bjoc.18.24

• natural substrate for sialidases and its chemical modification has been a useful approach to generate potent and selective inhibitors. Aiming at advancing the discovery of selective Trypanosoma cruzi trans-sialidase (TcTS) inhibitors, we have synthesised a small series of anomeric 1,2,3-triazole-linked

• , it is known that PLP is a TcTS weak inhibitor [35][38] and its inhibition does not involve formation of a Schiff-base intermediate [38]. However, an allosteric modulation of neuraminidase activity has been attributed to a selective modification of murine respirovirus neuraminidase via specific PLP

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

• , such as histone deacetylases. Keywords: chelated enolate; Claisen rearrangement; HDAC inhibitor; peptide; late stage modification; Introduction Among natural products, peptidic structures have entered the limelight due to their extraordinary biological activities [1]. Often found as secondary

• NMR spectra. The solubility issues forced us to investigate also other modification protocols. Thus, macrocycle 11 was subjected to an ozonolysis with subsequent Wittig reaction in a one-pot manner (Scheme 4). Performing the ozonolysis in presence of pyridine led to immediate reduction of the primary

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

• unsubstituted double bond next to the nitrogen atom permits a DHP to react as an enamine, for further transformation to complex heterocyclic scaffolds [26]. The exposed double bond can also undergo modification to produce different kinds of moieties. There are only few reports on the synthesis of C5–C6

Chemical and chemoenzymatic routes to bridged homoarabinofuranosylpyrimidines: Bicyclic AZT analogues

• Sandeep Kumar,
• Jyotirmoy Maity,
• Banty Kumar,
• Sumit Kumar and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2022, 18, 95–101, doi:10.3762/bjoc.18.10

• acetylation; Introduction In the last few decades, modification of nucleoside/nucleotide analogues has been a field of keen interest to researchers due to their therapeutic properties for treatment of cancer, viral and microbial infections [1][2][3][4][5][6][7][8][9]. The very first cytotoxic

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• , a linker with a higher degree of flexibility was designed. This goal was achieved by a modification of amine-containing amino acids in the i + 4 position through coupling to 4-carboxyphenylboronic acid, followed by intramolecular SMC. Different linker lengths were achieved by introducing ʟ-2,4

• in i + 4-position of the linear axin CBD sequence aAxWt were substituted by tryptophan and lysine, respectively, to have a higher analogy to the lysine modified SMC stapled peptides. Following the indications of DFT calculations, stapled peptide P5 was synthesised by modification of lysine in the i

• only generated with 7-aryl-Trp staple. C) On-resin modification of amines (n = 1: Dab, n = 2: Orn, n = 3: Lys) in i + 4 position to obtain organoboron side chains with increased linker flexibility. Reaction conditions: (a) Pd(PPh3)4, morpholine in DCM, 2 × 20 min; (b) carboxylic acid, HATU, DIEA in DMF

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• , which leads to formyl products from formal oxidative cleavage of a C=C bond. Our interest in vinylogous analogues of 2-nitroaryl photoreactive groups stems from studies into alkenylboronic acid reagents for Chan–Lam-type modification of peptide backbone N–H bonds, directed by a proximal histidine

• residue (Figure 1C, step, i + iv → ii) [18][19][20]. Subsequent investigations validated the use of photoreactive boronic acids as an approach to reversible backbone N–H modification via photocleavage of an alkenyl C–N bond [16][17]. Traditional 2-nitroaryl groups allow cleavage of benzylic C–X bonds (e.g

• noting that N-formyl products are themselves acylating reagents, and thus could find use in photochemical generation of selective acyl donors. Uncaging of peptide backbone N–H bonds from Chan–Lam-type modification. Photocleavage of compounds 1 and 6 under basic conditions. Yield of products was