Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• beige and light-yellow solids with 78% and 44% yield, respectively. Thermal analyses between 25 and 350 °C were performed in order to verify the hydration status of the bulk. Regarding hdz-CH3, a weight loss of 9.78% from around 80 to 190 °C was observed, suggesting the presence of two crystallization

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• split over two positions yielding in total 5.75 mol of water per CO2. The hydration is similar to that of native α-CD [13] and that of the krypton inclusion complex which has 5.28 water/Kr [14]. The CO2 molecule refines with an optimal occupancy of 0.84 and linear geometry (178.2(6)o) with C–O bond

• change in spectrum of 7 provided 7 and CO2 compete for the binding site. To avoid problems with formation of hydrogencarbonate the experiments were conducted in a buffer at pH 3 where only a minor fraction of the carbonic acid (pKa1 = 3.6) is dissociated and since the hydration constant of CO2 is small

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

• interconvertible to each other by hydration or dehydration, i.e., a plausible precursor of the allylic alcohol would be the diene, and vice versa [90]. Since both 8 and 10 are easily obtainable from 2 by Mozoroki–Heck coupling with commercially available 2-methyl-3-buten-2-ol, ester hydrolysis (LiOH in THF/H2O

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• (toluene, acetonitrile, DMSO-d6) at room temperature, or when these solutions were slightly heated, the compounds 5a,b,e dissociated to form APBTTs 1 (the solutions got violet color, characteristic of compounds 1) (Scheme 10). In the presence of water (including the atmospheric moisture), hydration

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• bicyclic scope was limited as other bicycles such as norbornene failed to react. The authors propose the catalytic cycle begins with the Rh(III)-catalyzed hydration of the alkynol to produce 186 followed by a Sc(III)-catalyzed addition to form the transient hemiketal 187. Ortho-C–H activation generates 188

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• %. The difference in the yield can be explained by the level of hydration, as was determined by TG (see below). For the 1:1:1 complexes, the mass loss is half in comparison with the water content of β-CD (6.4–7.4% for complexes and 14% for β-CD hydrate). On the other hand, the mass loss of the 3:1:1

• complexes is much higher (e.g., 11.8% for X3N complex). As a consequence, the 1:1:1 complexes lose relatively more hydration water than the corresponding 3:1:1 complexes. This can be explained by the high level of complexation for the 1:1:1 complexes. This aspect could be confirmed by thermal analysis

• especially appear for OH, CC and CH/CH2 bonds and groups. However, CD specific bands also appear for CH groups in the CD ring and α-type glycosidic bonds. Thus, a broad FTIR band corresponding to the stretching vibration of the O–H bonds in β-CD and hydration water molecules appears at ≈3301 cm−1. A weak

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• reactions of transition metal hydrides (Fe, Co, Mn, etc) with alkenes (e.g., Mukaiyama hydration) [20]. The last decade saw the development of milder methods for generating carbon-centered radicals as the advancement of their reactivity in cross-coupling reactions, the concept of photoredox catalysis [21

• Mukaiyama hydration [20] to furnish natural complexity. A similar approach was devised for the synthesis of modified meroterpenoids chevalone A (52), taondiol (53), decaturin E (54), and stypodiol (57, Scheme 4). For this purpose, tricycle 45 was prepared from compound 44 in gram-scale quantities by HAT

• (dba)3, SPhos, and Et3N in 86% yield. Reduction of the double bond with Pd/C followed by dual Stille coupling for the introduction of two methyl groups and Mukaiyama hydration utilizing Mn(dpm)3 and PhSiH3 furnished the misassigned structure for dysiherbol A (79). A revised structure was finally

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• technique after a synthetic transformation are highlighted in the following section (Scheme 14, Table 3). A continuous flow crystallization was performed using a trisegmented tubular crystallizer (KRAIC) coupled with a catalytic hydration of pyrazine carbonitrile [115]. After passing the reaction setup, the

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

• enone 10 to the corresponding allylic alcohol, followed by a Au-catalyzed alkyne hydration, providing hemiketal 11. This intermediate was in equilibrium with hydroxy-ketone 12, which was suitable for a SmI2-promoted cyclization, affording intermediate 13 selectively, already bearing rings C and D. The

• corresponding ketone was achieved using Dess–Martin periodinane with a pyridine buffer. Addition of Me3SiCH2Li efficiently afforded the Peterson adduct 33. The 1,1-disubtituted alkene was then submitted to Mukaiyma hydration to form the tertiary alcohol, in presence of Mn(dpm)3, PhSiH3 and O2. Then, the ketone

• ketone methylation gave access to 56. Directed C1–C5 vanadium-mediated epoxidation followed by DBU treatment and TBS deprotection afforded 57 in one pot. The tertiary alcohol 58 was obtained as a single diastereomer after hydration of position C18. Subsequent reduction with DIBAL-H gave the desired

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

• titration of a DMSO to a DMSO with 5 vol % of water was carried out to manifest the contamination with water (see Supporting Information File 1). Therefore, the exothermic signal from the dilution of CDs in DMSO was attributed to the hydration of hydroxy and, to a lesser extent, methoxy groups from

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

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

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• produced a bridged cyclic 2-oxabicyclo[2.2.1]hept-5-ene D. The further hydration of intermediate D gave intermediate E, which was in turn transferred to cyclopentenyl intermediate F by the ring opening of the bridge ring. In the cyclopentenyl intermediate F, the hydroxy group and the amide group clearly

On Reuben G. Jones synthesis of 2-hydroxypyrazines

• Pierre Legrand and
• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 935–943, doi:10.3762/bjoc.18.93

• amine) on the most electrophilic component of the α-ketoaldehyde (its aldehyde) to give intermediate 5. However, the ensuing cyclization (via a hydration of its imine bond to allow for a rotation) would then lead to compound 4 which is rarely the major reaction product. Since compound 3 is the main

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

• highly selective hydration/acylation of tertiary bromopropargylic alcohols with carboxylic acids promoted by alkali metal carbonates [24]. The reaction proceeds via the ring-opening of 1,3-dioxolan-2-one intermediates formed with hydroxy and alkynyl groups of bromopropargylic alcohol and alkali metal

• in 6–9% preparative yield. Hydrocarbonates CsHCO3 and KHCO3 were also tested in the reaction, which gave 5-bromomethylene-1,3-dioxolan-2-one 6a as a major product in 29–36% yield (Table 1, entries 11 and 12). Considering that hydration occurs during the formation of phenoxyketone 4a, we added water

• formation of phenoxyhydroxyketone 4 proceeds via 1,3-dioxolan-2-one 6 generated from bromopropargylic alcohol 1 and Cs2CO3. Then, Br-substitution/hydration of 6 and the release of CO2 give product 4 (Scheme 7). Apparently, diphenoxyketone 5 results from decarboxylative conversion of 1,3-dioxolan-2-one 7

Tenacibactins K–M, cytotoxic siderophores from a coral-associated gliding bacterium of the genus Tenacibaculum

• Yasuhiro Igarashi,
• Yiwei Ge,
• Tao Zhou,
• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku and
• Agus Trianto

Beilstein J. Org. Chem. 2022, 18, 110–119, doi:10.3762/bjoc.18.12

• /succinic acid module (Scheme 1, paths E1 and E2). The third elimination product, C15-ketene (structure in square brackets, Scheme 1) was not observed, but a pentadecenoate anion, appearing at m/z 239, warranted the existence of fragmentation path E3 and also the chain length of the acyl unit. Hydration of

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• . hypothesized that by conducting the reaction in the presence of water, the reaction would be diverted to an initial hydration followed by an α-ketol rearrangement [10]. First, it was determined with model 1-alkynylcyclobutanol derivative 24 that in anhydrous conditions, the major product was 25, resulting from

• the expected direct ring expansion (Figure 7). When the reaction was repeated in the presence of a single drop of water, however, only product 26 was observed, presumably by the hydration–rearrangement sequence. The intermediacy of the cyclobutyl α-ketol 27 was indirectly confirmed using diphenyl

• hypothesized by several groups that one could be the biological precursor of the other by means of a reversible hydration–rearrangement–dehydration sequence (Figure 16a) [24][25][26]. The presence of the diazo group in intermediates 78 and 79 is noteworthy in that this functional group has not yet been

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

• corresponding plausible mechanism is shown in Scheme 19. Firstly, Au-coordinated alkyne undergoes regioselective hydration to form intermediate 48. Then, intramolecular nucleophilic attack by azide occurs to give 2-carbonyl intermediate 49. Subsequently, intermediate 49 will undergo aromatization as well as the

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

• ), oxadiazole 3a gave the product of hydration of the acetylene bond (4d, yield of 65%) existing in solution as equilibrium between ketone and enol forms in a ratio of 1.2:1 according to NMR data (see Supporting Information File 1). Then, reactions of 5-acetylenyl-1,2,4-oxadiazole 3a–d with arenes (benzene and

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• of hydrophobic groups in the surface can reduce the hydration and limit cellular uptake [51][52]. It is therefore evident that more studies such as in-depth scattering studies are needed to fully elucidate the structure of the micelle [53]. Although TPP is present, it may not be fully available on

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• solved by a hydration reaction sequence on a well-soluble dimethoxytritylated precursor via in situ oxime formation. The synthetic path now provides a solid foundation to access O6-alkylated 7-aminomethyl-7-deazaguanines for the development of RNA labeling tools based on the preQ1 class-I riboswitch

• aminomethyl group is accomplished by a hydration reaction sequence via in situ oxime formation. The route now provides a solid basis to generate O6-alkylated preQ1 derivatives for the development of RNA labeling tools utilizing the RNA scaffold of the preQ1 class-I riboswitch. Experimental General. Chemical

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

• entropic effect characterized by negative ∆mH and ∆mS values. The essential structural feature of such polymers is their amphiphilic structure of hydrophobic domains and hydrophilic groups, which can form hydrogen bonds with water. These interactions result in a highly ordered hydration shell when the

• for ∆mH and, due to the ordered hydration structures, to a negative entropy of mixing. As soon as the turbidity temperature is reached, the hydrophobic effect becomes dominant and water molecules are released, leading to a collapse of the hydration shell and a significant increase in entropy. The

An initiator- and catalyst-free hydrogel coating process for 3D printed medical-grade poly(ε-caprolactone)

• Jochen Löblein,
• Thomas Lorson,
• Miriam Komma,
• Tobias Kielholz,
• Maike Windbergs,
• Paul D. Dalton and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2021, 17, 2095–2101, doi:10.3762/bjoc.17.136

• wettability. However, both graphs also show a time-dependent wettability decrease in the first 30 min after the withdrawal from immersion which might be in consequence of a hydration loss through water evaporation. Interestingly, this tendency is only followed by the dried PHEMA-coated sample and not by the

• dried pristine PCL scaffold. An explanation for this observation might be PHEMA´s ability to absorb water as well as the relative indistinct hydration state of PCL compared to PHEMA when fully hydrated. Toluidine blue staining was used as a rapid, colorimetric readout as it selectively binds to PHEMA

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• donors) for the hydration of olefins in the presence of cobalt complexes (Scheme 16) [56][57][58]. These findings enabled the application of neutral conditions, instead of the basic ones that employed borohydrides [59][60][61], to generate the metal hydride species, thereby expanding the functional group

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• modifications reported by chemists along with the synthesis of 2'-deoxy-2'-fluoro-nucleosides (FRNA) [24]. The negatively charged phosphodiester linkages in the backbones of DNA and RNA are of fundamental importance for reactivity, stability, conformation and hydration [25][26]. The sugar moieties in DNA and

• '-N compared to the 4'-O and 3'-O interactions in DNA. The 3'-amino moieties in the structure’s backbone were found to coordinate a larger amount of water molecules, on both the backbone and at groove sites. This increased hydration, as well as the configuration of the 3'-amino group enables the

• -phosphate backbone relative to native phosphodiester oligomers. This N-type sugar puckering and increased hydration of the sugar phosphate backbone could also account for the triplex-favoring properties of this modification [72]. Amide While many amide backbone oligonucleotide variants exist, the focus of