Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• leading to intermediate A, nucleophilic attack of phenolate at the less sterically hindered carbon of the above zwitterion A and subsequent protonation of anion B (Scheme 8). Based on these plausible mechanisms for the formation of phenoxyketones, it can be assumed that a decline of the Cs+ concentration

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

• reaction mechanisms: free radical autoxidation, cation radical autoxidation, and thermal intersystem crossing (ISC), using 18O2 labeling, spin-trapping, spectroscopic, mass spectrometric, kinetic, and computational techniques. After several experiments, the obtained results have demonstrated that the 2

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• several studies on the solvolysis mechanisms for alkanesulfonyl chlorides (RSO2Cl) and arenesulfonyl chlorides (ArSO2Cl). The earlier of these studies were reviewed a little over thirty years ago by Gordon, Maskill and Ruasse (Chem. Soc. Rev. 1989, 18, 123–151) in a contribution entitled “Sulfonyl

• of the review, the study is of solvolysis mechanisms and the reactions involve the solvolyses of a series of para and meta-ring-substituted substrates. Applying the Hammett equation to the rate measurements of Berger and Oliver [4], we arrive, in 50% water/50% acetone (v/v) at a reaction constant ρ

• defining mechanisms of nucleophilic substitution at sulphur are known to the writer...”. Examination of this section of the text shows, however, that it is limited to a consideration of substitution at the sulfur of sulfinates and reactions of the general type illustrated in Equation 3 and reactions

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• 1.44 ppm. ORTEP diagram of the asymmetric unit consisting of two cations 6b(A) and 6b(B) and triflate anions. Conversion of cyclic amino acids to 1,2-oxazole derivatives. Plausible mechanisms for the formation of 1,2-oxazoles 4a–h and VII from β-enamino ketoesters 3a–h with hydroxylamine. Synthesis of

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• % ee) could still be maintained (Scheme 6b). This one-pot three-component reaction would be more convenient for potential industrial applications. Finally, in order to understand the enantioselective formation process of product 3, we proposed the possible mechanisms for the [3 + 2] cyclization

The enzyme mechanism of patchoulol synthase

• Houchao Xu,
• Bernd Goldfuss,
• Gregor Schnakenburg and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 13–24, doi:10.3762/bjoc.18.2

• Chemistry, University of Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany 10.3762/bjoc.18.2 Abstract Different mechanisms for the cyclisation of farnesyl pyrophosphate to patchoulol by the patchoulol synthase are discussed in the literature. They are based on isotopic labelling experiments, but the

• calculations; enzyme mechanisms; isotopes; terpenes; Introduction Patchouli oil, the essential oil of the shrub Pogostemon cablin, has a pleasant woody odour and is of high economic value for the perfumery and cosmetics industries. It is mainly composed of sesquiterpenes with patchoulol as the main compound

• sesquiterpene (2-2H)-16 that may take up the deuteron released in the formation of 5 (and similar compounds) to give (2,15-2H2)-H (Scheme 3C). Notably, none of the proposed mechanisms in Schemes 1–3 can explain the reported results from all labelling experiments and some of the reported findings are even

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• arylative spirocyclization reaction delivered product 40a in comparable yield, suggesting an initial in situ reduction of the Fe(III) precatalyst occurs in the early stages of the catalytic cycle. Although the mechanisms of Fe-catalyzed cross-coupling reactions are often complex [74][75] (Scheme 8), the

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

Ligand-dependent stereoselective Suzuki–Miyaura cross-coupling reactions of β-enamido triflates

• Tomáš Chvojka,
• Athanasios Markos,
• Svatava Voltrová,
• Radek Pohl and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 2657–2662, doi:10.3762/bjoc.17.179

• 2D ROESY NMR analysis showing interaction between the alkenyl hydrogen and ortho-hydrogens on the aryl rings. Based on previously proposed mechanisms of isomerization in Suzuki cross-coupling reactions, we suggest the following explanation for the observed isomerization [25][29] (Scheme 3). In the

• -substituted enamides. Substrate scope of the Suzuki coupling leading to enamides 2 and 3. aRatio determined by 19F NMR; byield determined by 19F NMR using PhCF3 as an internal standard; cisolated yield; disolated as a mixture of isomers E/Z = 64:36. Proposed mechanisms for the formed Suzuki coupling retention

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• appears that in this case, both activation mechanisms, namely through hydrogen bonding and iminium ion formation are operating. Using the same chiral cinchona-based primary-tertiary diamine as catalyst (cat. 11), Zhai et al. developed a highly efficient intramolecular enantioselective aza-Michael addition

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

• Luke O. Jones,
• Leah Williams,
• Tasmin Boam,
• Martin Kalmet,
• Chidubem Oguike and
• Fiona L. Hatton

Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171

• during degradation of cryogels, the walls of the cryogel decrease in thickness and are in some cases broken. This analysis was made for enzyme-degraded cryogels, so it is unclear whether the process is likely to occur for cryogels degraded by other mechanisms such as disulphide cleavage [30][31] and

• deposition mechanisms, e.g., the maximum deposition force and/or syringe tip size (0.8 mm used for hydrogels) for certain printers, place restrictions on highly viscous materials. These material properties have a direct influence on the final printing resolution. The resolution should be adequate for

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• widely investigated, because they are abundant and less expensive. This review discusses the scope and application of photoinduced copper-based catalysis along with recent progress in this field. The special features and mechanisms of copper photocatalysis and highlights of the applications of the copper

• ; mechanisms of copper photocatalysis; photoinduced copper-based catalysis; photoredox catalysis; special features of copper photocatalysis; Introduction Solar light is an inexhaustible and free energy source for green plants and bacteria. Photosynthetic organisms absorb solar energy and convert it into

• discourage development of ruthenium and iridium-based catalysts [21]. Copper salts have become popular materials for photoredox catalysts due to their abundance, low cost, and ability to provide strong photoexcited reducing power [21][22][23][24]. In this review, the different catalysis mechanisms between

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• indicated that structurally diverse polymers formed by different polymerization mechanisms can readily be linked just by a simple NIR-induced CuAAC reaction. The macromolecular scope was further extended to the preparation of cross-linked materials. Thus, the formulations containing bisphenol A di(3-azido-2

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• introduce the applications of the products and the reaction mechanisms for the synthesis of corresponding N-heterocycles. Keywords: 1,3-enyne; functionalization; pyridine; pyrrole; tandem annulation; Introduction The pyridine moiety is an important class of six-membered N-heterocycles that is widely found

Targeting active site residues and structural anchoring positions in terpene synthases

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

• mechanisms; isotopes; site-directed mutagenesis; terpenes; Introduction Terpenoids now span more than 90,000 known compounds, which makes them by far the largest class of natural products [1]. Despite this fact, all compounds are made from only two C5 building blocks, dimethylallyl diphosphate (DMAPP) and

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• bond of these oxadiazoles quantitatively resulted in E/Z-vinyl triflates. The reactions of the cationic intermediates have been studied by DFT calculations and the reaction mechanisms are discussed. Keywords: acetylene-oxadiazoles; Friedel–Crafts reaction; hydroarylation; superelectrophilic activation

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• . To be effective, the desired cyclization needs a second methoxy substituent ortho- or para- to the leaving group, which in this case is an aromatic methoxy substituent. Based on these results we suggest two possible mechanisms for these transformations. Both would proceed through an intermediary

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• outline the existing knowledge on thermosensitive polymers from a physicochemical rather than a synthetic point of view in order to gain a deeper understanding of the mechanisms involved in the phase transition with upper critical demixing point versus lower critical demixing point. The fundamental

• intra- and intermolecular interactions between polymer segments are favored and the polymer begins to precipitate. A comparison of the calorimetrically determined enthalpies of mixture ∆mH for PNAGA and PNIPAAm reveals the different mechanisms. The entropically driven LCST phase transition of PNIPAAm

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• the similar mechanisms. First, the Brønsted or Lewis acid coordinates with silane 51 leading to a solvent-stabilized electron-deficient silane complex 57, where N-protected indole attacks in a Friedel–Crafts fashion to give the 3-silylindoles 60 along with molecular hydrogen (Scheme 7b and Scheme 7d

• indolyl amines through Buchwald–Hartwig cross coupling. Synthesis of 3,3’-bis(indolyl) ethers. C–H silylation of indoles. n-BuLi-mediated syntheses of bis(indol-3-yl)silanes. Acid-catalyzed syntheses of bis(indol-3-yl)silanes and mechanisms. B(C6F5)3 and Al(C6F5)3-catalyzed syntheses of bis(indol-3-yl

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• mechanisms occur in parallel, which results in the formation of the Michael adduct as a byproduct and the desired spirocyclopentanes 104. It is noteworthy that the mechanistic studies showed that the product is formed through a concerted mechanism and therefore is not part of an intermediate adduct. A

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• have been used as additives in these reactions and are suggested to act as ligands, assist proton transfer and promote the formation of oligovanadates by decreasing the pH value of the solution. The mechanisms of some vanadium-mediated oxidation reactions of alkanes have been studied, most of them

• methods include V2O5 and VO(acac)2 used for the alkylation of 2-naphthol and nitrogen-containing heteroaromatic moieties containing N-methylmorpholine-N-oxide, tetrahydroisoquinolines, and N,N-dimethylacetamide [107][108][109][110][111][112][113]. The mechanisms involving oxidation of the amine mediated

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• . The key features of ASOs further enable them to be transformed into personalized medicines, eventually even targeting patient-specific sequences and very rare diseases [1]. ASOs can mediate gene silencing via different mechanisms of action. ASOs that induce RNase H degradation of the endogenous RNA

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• , physiological adaptations and chemical defence mechanisms to optimize their living conditions and resist competitors, parasites and predators [3][4][5]. These bioactive compounds are often considered as secondary metabolites (SM) which are involved in communication, symbiotic interactions, pathogenicity or

• human pathogenic fungi like A. fumigatus, one of the most common airborne fungal pathogens, might lead to new insight in virulence mechanisms and the role of SMs therein [32]. The aim of this review is to depict the fungal secondary metabolite potential and its role in an ecological context using A

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• and reactions of these reagents are described chronologically and the review also discusses the relative fluorination power of each reagent and their mechanisms chronicling developments from a historical perspective. Keywords: N-F fluorinating agent; fluorination; fluorodiazoniabicyclo[2.2.2]octane

A systems-based framework to computationally describe putative transcription factors and signaling pathways regulating glycan biosynthesis

• Theodore Groth,
• Rudiyanto Gunawan and
• Sriram Neelamegham

Beilstein J. Org. Chem. 2021, 17, 1712–1724, doi:10.3762/bjoc.17.119

• mechanisms that may contribute to different glycan signatures. In our analysis, TF–glycogene relationships for breast cancer derived by filtering Cistrome Cancer DB were enriched for the glycosylation pathways. Figure 3 summarizes these cancer-related TF–glycosylation pathway relationships for luminal (type