Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• transformations and ex situ NMR monitoring of the dyad composition evolution [90]. It was found that Gr1 first interacts with PCOE so that all Ru-carbenes become bound to those macromolecules approximately within one hour (Scheme 9, reaction 1 and Figure 7). Recall that the addition of Gr1 to a mixture of NB and

First synthesis of cryptands with sucrose scaffold

• Patrycja Sokołowska,
• Michał Kowalski and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2019, 15, 210–217, doi:10.3762/bjoc.15.20

• (TLC monitoring: dichloromethane/methanol 10:1). The reaction mixture was then cooled to room temperature, diluted with toluene (5 mL), and acetonitrile was removed in vacuum. The remaining toluene solution was passed through a short pad of Celite, concentrated, and the residue was purified by flash

• ’-penta-O-benzylsucrose (17): To a solution of triol 2 (88 mg; 0.11 mmol) in toluene (3 mL), allyl bromide (56 μL, 0.66 mmole, 6 equiv) was added followed by 50% aq NaOH (3 mL), and the heterogeneous mixture was vigorously stirred at 50 °C for 18 h (TLC monitoring hexane/ethyl acetate 4:1). The mixture

• borohydride (400 mg), and the mixture was stirred for 16 h (TLC monitoring dichloromethane/methanol 20:1). Water (5 mL) was added followed by 10% aq NaOH (5 mL) and brine (5 mL), and the mixture was stirred at rt for another 30 min. The organic phase was separated and the aqueous one was extracted with CH2Cl2

Unexpected loss of stereoselectivity in glycosylation reactions during the synthesis of chondroitin sulfate oligosaccharides

• Teresa Mena-Barragán,
• José L. de Paz and
• Pedro M. Nieto

Beilstein J. Org. Chem. 2019, 15, 137–144, doi:10.3762/bjoc.15.14

• -phase synthesis, such as easy reaction monitoring by standard techniques and low consumption of donor building blocks to complete glycosylations. During the course of this investigation, unexpected stereochemical outcomes were observed in glycosylations involving glycosyl donors containing an N

• leads to the selective formation of the desired 1,2-trans glycosidic linkages and can be easily removed at the end of the synthesis [7][8][36][42]. Moreover, 19F NMR experiments can be employed to assist in the analysis and monitoring of reactions involving N-TFA building blocks. First, we describe the

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• very easily loses CO2 which causes the signal at m/z 309. This behavior could be confirmed by induced fragmentation experiments (see below). Monitoring the temporal progress of reaction R3 was achieved by taking small samples at regular intervals, diluting and swiftly feeding them into the spectrometer

• nm): 368.0 nm global maximum. HRESIMS: [M]+ calcd for C33H26N4P+, 509.1890; found, 509.1884. ESI-CID (Figure S4, Supporting Information File 1). Charge-tagged L-proline-derived catalyst 1∙Cl [18]. NMR monitoring of reaction R1 in deuterated DMSO (concentration of tetrazine 0.005 mmol/mL). a) ESI mass

• spectrum of reaction R1 after 26 min. b) ESIMS monitoring of reaction R1. To better visualize the trend of III1, the signal intensities of III1 have been multiplied by a factor of two. ESI mass spectrum of reaction R1 with preformed I1 8 minutes after adding substrate 2. ESI mass spectrum of reaction R2

Degenerative xanthate transfer to olefins under visible-light photocatalysis

• Atsushi Kaga,
• Xiangyang Wu,
• Joel Yi Jie Lim,
• Hirohito Hayashi,
• Yunpeng Lu,
• Edwin K. L. Yeow and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2018, 14, 3047–3058, doi:10.3762/bjoc.14.283

• DMSO, 410 nm pulse excitation and monitoring emission at 480 nm) were recorded in the absence of a quencher, and in the presence of xanthate 1a and 1-octene (2a, 40 mM, Figure 1C). The lifetime profiles were described using a mono-exponential decay function with a lifetime of 1.40 μs in the absence of

Unnatural α-amino ethyl esters from diethyl malonate or ethyl β-bromo-α-hydroxyiminocarboxylate

• Eloi P. Coutant,
• Vincent Hervin,
• Glwadys Gagnot,
• Candice Ford,
• Racha Baatallah and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2853–2860, doi:10.3762/bjoc.14.264

• the water formed in situ. The 1H NMR monitoring of crude samples pointed out a complete conversion, most often overnight at 60 °C, and the resulting solutions of alkylidenemalonates 6a–al were then directly reduced to give the malonates 3a–al. For this reduction step, palladium-based catalytic

• results, we first sought an explanation for the modest yields observed for the preparation of the 2, 3 or 4-chlorophenyl-α-hydroxyimino esters 2t–v. As depicted in Scheme 2, the 1H NMR monitoring of the ethanolic solution of the alkylidenemalonate 6u pointed out a slow but steady 1,4-addition of ethanol

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• . As seen by 1H NMR monitoring, the treatment of arylaldehydes 3a–s with trimethyl orthoformate and an acid-bearing resin in dry methanol led to full conversion into the corresponding acetals 5a–s. Then, as reported [7][8], heating the crude acetals 5a–s and ethyl nitroacetate (4) in the presence of

• focused on the model preparation of the trifluoromethyl-bearing α-nitro ester 6j from acylals 7 depicted in Scheme 2. As well reviewed [14], acylals can be prepared from aldehydes and anhydrides using a variety of acids as catalysts. In our case, 1H NMR monitoring of the reaction between 2

• monitoring of the reaction between compounds 7 or 8 and ethyl nitroacetate (4) in the presence of a catalytic amount of indium(III) chloride pointed out the occurrence of tangibly more of the expected acrylate 2j, although along with many byproducts. Indeed, in a typical experiment, upon reduction of the

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• reacted with hydrazine hydrate (5a) in refluxing ethanol containing a catalytic amount of AcOH (Scheme 2). TLC monitoring of the reaction indicated full conversion of 4 within 4 h reaction time to afford a fairly polar product insoluble or only slightly soluble in all commonly used NMR solvents. However

Design and synthesis of C₃-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

• Sambasivarao Kotha,
• Saidulu Todeti and
• Vikas R. Aswar

Beilstein J. Org. Chem. 2018, 14, 2537–2544, doi:10.3762/bjoc.14.230

• ), silicon tetrachloride (SiCl4, 0.61 mL, 5.36 mmol) was added dropwise at 0 °C and the reaction mixture was stirred for 10–15 min at the same temperature. Later, the reaction mixture was stirred at room temperature for 20 h. After completion of the reaction (TLC monitoring), the reaction mixture was

• ethylene atmosphere at rt. After completion of the reaction (TLC monitoring), the solvent was removed under reduced pressure. Later, the crude product was purified by silica gel column chromatography (30% EtOAc/petroleum ether) to obtain the ROM product 13 as a colourless solid (310 mg, 56%); Rf = 0.68 (4

• monitoring), the reaction mixture was quenched with 1 M aq HCl solution, and the aqueous layer was extracted by EtOAc (3 × 10 mL). Then the organic fraction was washed with brine solution, dried over Na2SO4 and concentrated. The crude residue was purified by silica gel column chromatography (10% EtOAc

Comparative cell biological study of in vitro antitumor and antimetastatic activity on melanoma cells of GnRH-III-containing conjugates modified with short-chain fatty acids

• Eszter Lajkó,
• Sarah Spring,
• Rózsa Hegedüs,
• Beáta Biri-Kovács,
• Sven Ingebrandt,
• Gábor Mező and
• László Kőhidai

Beilstein J. Org. Chem. 2018, 14, 2495–2509, doi:10.3762/bjoc.14.226

• cell movement or locomotion) of conjugates were investigated by monitoring the locomotion of A2058 cells with holographic microscopy under the condition that the conjugates (10−7 to 10−5 M) were added directly to the cells in a uniform concentration. For the characterization of cellular movement, three

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• . The maximum conversion of around 97% is reached for both catalysts within 60 minutes. Accordingly, we aimed at further monitoring the substrate scope of the complexes including the metathesis of terminal alkynes as well as ring-closing alkyne metathesis (RCAM). Table 2 summarizes the isolated yields

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• ) sulfate and ascorbic acid. TLC monitoring showed that the cyclization failed. Then, tris(benzyltriazoylmethyl)amine (TBTA) [40][41][42] was added as catalyst and macrocycle 4 was formed in 71% yield, which is extremely high for an intramolecular cyclization. The dimeric product 3 and the cyclic dimer 5

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• methods All reactions were carried out under argon atmosphere in solvents that were purified and dried before use by common methods. Monitoring of the reaction course was accomplished by thin layer chromatography (TLC) on silica gel SIL G/UV254 plates (Marcherey, Nagel & Co.). Chromatography was performed

A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines

• Katherine E. Jolley,
• Michael R. Chapman and
• A. John Blacker

Beilstein J. Org. Chem. 2018, 14, 2220–2228, doi:10.3762/bjoc.14.196

• monitoring of the steady-state conversion in continuous flow by 1H NMR. Following an optimization study, it was found that the Cu catalyst could be omitted when operating at 100 °C for 1 hour reaction time in batch, providing quantitative conversion to product (Table 2, entry 4). Conducting the same reaction

Revisiting ring-degenerate rearrangements of 1-substituted-4-imino-1,2,3-triazoles

• James T. Fletcher,
• Matthew D. Hanson,
• Joseph A. Christensen and
• Eric M. Villa

Beilstein J. Org. Chem. 2018, 14, 2098–2105, doi:10.3762/bjoc.14.184

• over time was used to calculate initial reaction rates for each of the amines studied, as described in the experimental section. It is important to note that this monitoring detects only the endpoint of the three-step sequence of condensation, rearrangement and hydrolysis steps, whereupon para

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• dye are regenerated. This principle has enabled, for example, real-time monitoring of enzymatic activity [18][19][20], the detection of membrane-transport activity [21] and membrane fusion [22], and even cellular imaging appears to be a potential future prospect [23][24]. However, most combinations of

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• also exhibits LCST behavior. Compound 3 is soluble in aqueous media at 20 °C, the solution becomes turbid at 40 °C, and turns back to a clear solution upon cooling. The clouding point of 3 was determined by monitoring the transmittance change (Figure 3). The clouding point of 3, determined by

• monitoring the transmittance change, was 24 °C (2 mM in aqueous solution, Figure 3a, black line) which is 18 °C lower than the clouding point of 1 (42 °C, Figure 3b, black line) [5]. This is due to the fact that the benzene units carrying the hydrophobic alkyl chain ring in 3 are more hydrophobic than the

Assessing the possibilities of designing a unified multistep continuous flow synthesis platform

• Mrityunjay K. Sharma,
• Roopashri B. Acharya,
• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2018, 14, 1917–1936, doi:10.3762/bjoc.14.166

• 411008, India 10.3762/bjoc.14.166 Abstract The multistep flow synthesis of complex molecules has gained momentum over the last few years. A wide range of reaction types and conditions have been integrated seamlessly on a single platform including in-line separation as well as monitoring. Beyond merely

• important drug molecules and discussed challenges involved in developing such a control process [60]. Monitoring: Utilization of in-line analysis techniques and constant monitoring of the product also requires specialized equipment to be used and relative ‘analysis time’ in the whole process sequence is

• monitoring a given reaction/purification) but that can be added at the specific steps wherever needed. 6. Utility: At this point of time it is assumed that for each reaction step the heating or cooling arrangement (also referred as ‘utility’ in the chemical process engineering and plant operation) is

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• comparatively poorer yields (Table 2, entries 10–12). Monitoring of the reaction at different time intervals under otherwise identical conditions showed slightly progressive increase in the yield of the product formed (Table 2, entries 13–15) with a maximum yield of 93% after 4 hours (Table 2, entry 9). However

Preparation and X-ray structure of 2-iodoxybenzenesulfonic acid (IBS) – a powerful hypervalent iodine(V) oxidant

• Irina A. Mironova,
• Pavel S. Postnikov,
• Rosa Y. Yusubova,
• Akira Yoshimura,
• Thomas Wirth,
• Viktor V. Zhdankin,
• Victor N. Nemykin and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 1854–1858, doi:10.3762/bjoc.14.159

• under Ishihara's conditions [13] in water at 70 °C (Scheme 2). NMR monitoring indicated 95% conversion of the starting sodium salt 5 to the iodine(V) product 6 after about 3 h stirring at 70 °C (Figure S1 in Supporting Information File 1). After cooling the aqueous solution to room temperature, the

• from the literature that sodium periodate can oxidize various ArI to ArIO2 in boiling water or aqueous acetic acid [19][20]. We have found that according to NMR monitoring (Figure S2 in Supporting Information File 1), the reaction of sodium 2-iodobenzenesulfonate (5) with sodium periodate in water

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

• Jie Gao,
• Zhe Zheng,
• Lin Shi,
• Si-Qi Wu,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157

• quality of pharmaceutical formulations, as well as monitoring drug plasma concentrations, analyzing drug biodistribution in bone tissue, and detecting drug excretion in urine. For example, BPs are of poor bioavailability if orally administered (generally with absorption less than 1%) and about 50% of the

• ]arene (GC5A, Scheme 1b). Such label-free sensing strategy exhibits potential application in real-time monitoring concentrations of BPs in urine and pharmacokinetic studies. Results and Discussion The main skeleton of BPs possesses two phosphate groups which are potential binding sites and therefore GC5A

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• spectra were registered with a FTIR NEXUS spectrometer (as film or KBr pellets). UV–vis spectra were recorded using a UV–vis JASCO V-630 spectrophotometer. Melting points were determined in capillaries with a Stuart SMP30 apparatus with automatic temperature monitoring. Starting materials: 1,4

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• hour. The use of CuNPs greatly facilitated the monitoring of the reaction and the work-up, as these nanomaterials being easily removed from the crude mixture by simple centrifugation. To our delight, [Ru(TAP)2phen]2+-calix[4]arene-[c-(RGDfK)]4 conjugate 9 was isolated in 31% yield after purification by

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• disappointment, the attempted O,O’-bis-alkylation of 1 with 1-iodooctane (Williamson etherification, Table 1, entry 1), afforded a multicomponent reaction mixture (TLC monitoring, 100% conversion of 1), from which we succeeded in isolating only G-0 chloro-dendron 2a and the O,O’,N-tris-alkylated side product 2b

• K2CO3 as proton scavenger) resulted in no dendrimer formation; decomposition of D-N

  NH was observed instead (as determined by additional NMR monitoring). Nevertheless, the desired G-2 dendrimer 5 could be obtained through an alternative route, namely, by amination of G-1 chloro-dendron D-Cl with

• )alkanoic acid-based tripodal melamines into the corresponding tri acid chlorides (not depicted in Scheme 4) followed typical procedures (in refluxing thionyl chloride with SO2 and HCl generation), a long reaction time (up to 24 h, as determined by HRMS monitoring) was mandatory for this transformation to

Drug targeting to decrease cardiotoxicity – determination of the cytotoxic effect of GnRH-based conjugates containing doxorubicin, daunorubicin and methotrexate on human cardiomyocytes and endothelial cells

• Livia Polgár,
• Eszter Lajkó,
• Pál Soós,
• Orsolya Láng,
• Marilena Manea,
• Béla Merkely,
• Gábor Mező and
• László Kőhidai

Beilstein J. Org. Chem. 2018, 14, 1583–1594, doi:10.3762/bjoc.14.136

• for real-time monitoring of cells to distinguish short-term (0–2 hours) and long-term (0–72 hours) effects elicited by the drug or carrier–drug conjugates. The basic theory of impedimetry is that proliferation/viability of cells is well detectable by monitoring of the electric impedance (Z) in an AC