(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• and aldehyde protecting groups. Recently, Lebold, Sarpong, and co-workers showed that 1,2-BCPs (±)-14a–e are also accessible from 1,5-disubstituted 2-azabicyclo[2.1.1]hexanes 13 (2-aza-1,5-BCHs) through a skeletal editing strategy utilising commercially available Levin’s reagent [30][31] (Scheme 1D

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• partial conversion of the starting material was observed. We postulated that the presence of two Boc protecting groups on the nitrogen makes the oxidation of the C-centered radical challenging. By using 1o only bearing one protecting group the desired product could be obtained, albeit in only 17% yield

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• undertaking a 1H NMR spectroscopic kinetic survey of solvent, ligand, and substituent effects on the general reaction 1 → 3 (with a variety of N-protecting groups), to supplement known qualitative observations. We found that, (1) electron-withdrawing phosphines accelerate hydroamination, (2) reactions are

Optimizations of lipid II synthesis: an essential glycolipid precursor in bacterial cell wall synthesis and a validated antibiotic target

• Milandip Karak,
• Cian R. Cloonan,
• Brad R. Baker,
• Rachel V. K. Cochrane and
• Stephen A. Cochrane

Beilstein J. Org. Chem. 2024, 20, 220–227, doi:10.3762/bjoc.20.22

• combinations of protecting groups on glycosyl acceptors and donors, as represented by compounds 1a and 2a in Figure 2, are proficient in the efficient generation of lipid II disaccharide [35][36]. Subsequently, significant endeavors have been directed towards the exploration of glycosyl donors, such as N

• . Finally, the benzyl-protecting groups in compound 7 were cleaved via hydrogenolysis, followed by co-evaporation of the resulting crude product in pyridine. This yielded a monopyridyl salt, setting the stage for the final lipid coupling and deprotection sequence. To establish the vital lipid diphosphate

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• and straightforward as it is usually considered. Keywords: concentration; glycosylation; protecting groups; reactivity; sialic acids; stereoselectivity; Introduction Glycoconjugates containing sialic acid occur on the surface of all cell types in a variety of organisms. They participate in a broad

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• been developed for further interaction studies with lectins (galectins and siglecs). The synthesis of the 3’-Su-TF antigen 2 comprises eight steps from the known N-galactosamine donor 3, where two of the steps, removal of the Troc- and DTBS protecting groups are performed in the same pot and the

Long oligodeoxynucleotides: chemical synthesis, isolation via catching-by-polymerization, verification via sequencing, and gene expression demonstration

• Yipeng Yin,
• Reed Arneson,
• Alexander Apostle,
• Adikari M. D. N. Eriyagama,
• Komal Chillar,
• Emma Burke,
• Martina Jahfetson,
• Yinan Yuan and
• Shiyue Fang

Beilstein J. Org. Chem. 2023, 19, 1957–1965, doi:10.3762/bjoc.19.146

• long ODN synthesis and purification, correct sequence selection, gene construction to protein synthesis has been established. Because the present long ODN synthesis method does not need PCR assembly or ligation of short ODNs and secondary structures of ODNs are prevented by protecting groups during de

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• [indoline-3,5'-[1,2]diazepines] 3a–m were obtained in reasonable to good yields. Both, α-chloro- and α-bromo-N-acylhydrazones could be successfully used in the reaction and gave similar results. Also, hydrazones with different benzoyl-protecting groups were well tolerated in the reaction. In general, α

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• through Sonogashira cross-coupling reactions with alkynes featuring different protecting groups such as TIPS, TES, and TIBS. Scheme 7 illustrates the derivatization process using one of the chosen examples, specifically the TIPS group. Accordingly, the cross-coupling products 33a–c were obtained in yields

• affected by the molecular packing, they have modified compound 34a using different protecting groups. In this context, triethylsilyl (TES), triisopropylsilyl (TIPS), and triisobutylsilyl (TIBS) groups were incorporated into the structure considering the increased dimensions. Thus, derivatives 34a-TES and

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• sulfur reagents resulted in thiolated products 92 up to 99% ee, in the presence of quinidine as the organocatalyst (Scheme 38) [72]. For the study of enantioselectivity of products, different N-substituted oxindoles with H, Me, phenyl, and benzyl groups were investigated. As the size of N-protecting

• groups increased, the percentage of enantioselectivity decreased, where in the case of NH-oxindoles, the product was achieved with only 6% ee. Another sulfenylation at the 3-position of unprotected oxindoles with N-(phenylthio)phthalimide was reported by Feng et al. [73]. A chiral N,N′-dioxide-Sc(OTf)3

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• mesylation produced 17.3. Then, the nucleophilic substitution (SN2) reaction of benzoate with 17.3 produced the benzoate ester 17.4 with an inversion of configuration. Then, the two protecting groups (ester and trityl) were removed to produce (S)-17.6. The modification of the sn-2 position is illustrated in

• ) myo-inositol (20.6). The oxidation of the phosphite intermediate with m-CPBA followed by the catalytic hydrogenolysis of the benzyl protecting groups produced PIP3-PAF (20.7). 2 Edelfosine and diether analogues PAF and PAF-analogues that feature an acyl or more generally an ester group in sn-2

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• -workers demonstrated an enantioselective aza-Friedel–Crafts reaction between indoles 4 and isatin-derived ketimines 49. A chiral phase transfer catalyst O3 derived from urea assisted this organic transformation featuring a C3–H bond functionalization of indoles. Different protecting groups for the imine

• nitrogen and ring nitrogen of 49 were screened under optimal reaction conditions where Cbz and benzyl were the best protecting groups in terms of enantioselectivities. A product library was prepared by varying sterically and electronic divergent functionalities in the carbocyclic rings of both reactants

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• Information File 1, Figure S1) due to the protecting groups complicates the analysis of the reaction products. However, the olefinic signals were a pair of two doublets representing two vicinal vinylic protons [6.48 (d, J = 8.0 Hz, 1H), 6.29 (d, J = 8.0 Hz, 1H), 5.31 (d, J = 8.0 Hz, 1H), and 5.28 (d, J = 8.0

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

• several imines bearing various N-protecting groups [48]. We have argued that this protecting group could influence the enolate addition. Indeed, an effect of the nitrogen protecting group was observed. Interestingly, small sulfonyl-based protecting groups led to the (R,R,S)-diastereoisomer of the product

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

• 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

• –Tishchenko method [31][32], in presence of SmI2 and an aldehyde (Scheme 4). para-Nitrobenzaldehyde was used [33] to introduce a labile para-nitrobenzoate on the product, planning an easy deprotection of the alcohol. This would also pave the way to an orthogonal manipulation of protecting groups on the

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• 1,3-Dithianes are text book examples of versatile organic synthesis building blocks. They are familiar carbonyl protecting groups, but are more commonly known as ‘umpolung’ reagents, or acyl anion equivalents [1][2][3][4][5][6]. This is because they can be readily metalated and alkylated, allowing the

• (101), without the need for any protecting groups (Scheme 15b). Our group has also investigated non-cyclic analogs of 5,6-dihydro-1,4-dithiin-2-ylmethanol (90), such as the dimethylthio-substituted allyl alcohol 105 (Scheme 16) [103]. Surprisingly, we have found that these allyl alcohols totally lack

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• protecting groups followed by hydrolysis of the acetyl protecting groups, affording the desired product with spectral data identical to reported natural samples. Shirahama’s synthesis was an illustrative example that rings A, B and the bicycle CD of grayananes could all be obtained by SmI2-promoted steps

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• conditions the oxidative ABNO-catalyzed α-cyanation of amines was realized with no need for N-protecting groups [105] (Scheme 16B). The key reactive species proposed in these electrochemical reactions are the oxoammonium cations formed from the amine-N-oxyl catalyst at the anode. The oxoammonium cation

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• -1-deazapurine [16], the key reactions are copper-catalyzed benzyl ether formation and site-specific nitration. The application of protecting groups was necessary for reasons of solubility and to improve selectivity. The obtained heterocycles may serve as core compound for further structural

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• functionalizing these molecules, for example, by inserting some protecting groups. Substituted heptacenes demonstrate remarkable stability and exceptional electric properties. Nevertheless, studying the properties of unsubstituted acenes is also essential. We guessed that some increase in solubility of acene

Solid-phase total synthesis and structural confirmation of antimicrobial longicatenamide A

• Takumi Matsumoto,
• Takefumi Kuranaga,
• Yuto Taniguchi,
• Weicheng Wang and
• Hideaki Kakeya

Beilstein J. Org. Chem. 2022, 18, 1560–1566, doi:10.3762/bjoc.18.166

• synthesis. Third, the peptide chain was cyclized in the solution phase, followed by simultaneous cleavage of all protecting groups to afford longicatenamide A. Chromatographic analysis corroborated the chemical structure of longicatenamide A. Furthermore, the antimicrobial activity of synthesized

• chemical communication. The retrosynthesis of peptide 1 is displayed in Scheme 1. First, the cyclic peptide 1 was linearized by retrosynthesis, and acid-labile protecting groups were attached onto the reactive side chain. The biomimetic synthesis of cyclic peptides often enables efficient synthesis [12][13

• 29. Then, five rounds of DIC/Oxyma-mediated amidation [22] and Nα-deprotection with piperidine led to resin-bound peptide 5. Treatment of 5 with TFA/CH2Cl2 1:99 released 30 into the solution without unmasking the acid-labile protecting groups of the side chains. Subsequently, peptide 30 was cyclized

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• carbazates. In the synthesis of product 3a the intermediate α-chlorohydrazone 9a was not isolated. The preparation of mixed oxime-hydrazones 5 and 7 was more challenging as it required a modular synthetic approach and the use of protecting groups. The developed synthetic route starting from benzylamine is

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

• diastereomers. Therefore, we decided to oxidize the acetal in 23 to the corresponding lactone (Scheme 9). The acetal was first hydrolyzed to the hemiacetal 24 in quantitative yield. Oxidation of 24 proved delicate due to the lability of the tertiary allylic alcohol, and the presence of acid-sensitive protecting

• groups. Several conditions were tested: silver oxide on celite [33] failed to give any conversion. PCC with sodium acetate [34] gave only traces of the target lactone 25. However, the use of the Jones’ reagent gave reproducible yields of 25, together with the deprotected alcohol 26. Under optimized

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

• diffuse intermolecular C–H···O contacts involving the phosphate and acetyl oxygen atoms. Deprotection of 16 was completed in two steps, first using hydrogenolysis with Adam’s catalyst (PtO2), followed by removal of the acetate protecting groups with Et3N/H2O/MeOH, and furnished the target glycosyl 1

A versatile way for the synthesis of monomethylamines by reduction of N-substituted carbonylimidazoles with the NaBH₄/I₂ system

• Lin Chen,
• Xuan Zhou,
• Zhiyong Chen,
• Changxu Wang,
• Shunjie Wang and
• Hanbing Teng

Beilstein J. Org. Chem. 2022, 18, 1032–1039, doi:10.3762/bjoc.18.104

• particularly suitable for peptide chemistry since protecting groups are often required in peptide synthesis [52][53]. These multistep reaction methods are conducive to avoid overmethylation products. Although procedures for the synthesis of monomethylamines have been developed over the past years, the starting