Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• as a flattened oxacarbenium intermediate (Scheme 1a). Early attempts to achieve some stereocontrol of glycosylations were mainly dedicated to the development of participating groups and optimization of the reaction conditions. More recently, the research emphasis is switching towards understanding of

Solid-state mechanochemical ω-functionalization of poly(ethylene glycol)

• Michael Y. Malca,
• Pierre-Olivier Ferko,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2017, 13, 1963–1968, doi:10.3762/bjoc.13.191

• -diisopropylethylamine (DIPEA) led to 1H NMR yields of 21% and 17%, respectively (Table 1, entries 2 and 3). Switching to NaOH as the base led to a sharp increase of mPEG conversion to 81%. The highest conversions were obtained by using mPEG, NaOH and TsCl in respective stoichiometric ratios of 1:1.2:1.5 (Table 1, entry

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• selectfluor [101][102]. They could control the selectivity of the reaction through LAG using ACN (≈10% v/v of total materials) to get predominantly mono-fluorinated product over difluorinated derivatives (Scheme 27). Contrastingly, addition of 1.0 equiv of Na2CO3 led to switching of the selectivity

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• -butyl and trimethylsilyl derivatives displayed no reactivity. With 2-naphthyl and p-nitrophenylsulfonamides as poorly reactive compounds, additional LAG screening experiments were required to establish the optimal reaction conditions by switching to acetone as the grinding liquid, prolonging the milling

Grip on complexity in chemical reaction networks

• Albert S. Y. Wong and
• Wilhelm T. S. Huck

Beilstein J. Org. Chem. 2017, 13, 1486–1497, doi:10.3762/bjoc.13.147

• system level behavior of larger networks [25]. In fact, simple motifs with a few positive and negative feedback loops create functionality, such as bistable switching, adaptation and oscillations [26]. Such building blocks can be reconstructed, and this has sparked enormous activity in the fields of

Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid

• Kohei Yamada,
• Naoto Kamimura and
• Munetaka Kunishima

Beilstein J. Org. Chem. 2017, 13, 1478–1485, doi:10.3762/bjoc.13.146

• , utilization of Na+ and K+ as counter cations for the additive provided inferior results (Table 2, entries 8 and 9). Interestingly, switching the counter cation of the base to Li+ did not afford any product (Table 2, entry 10). The reaction with PdCl2(dppf) instead of NiCl2(dppf) reduced the outcome of the

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• potential for switching the activation mode from a SET process to a direct heterolytic photolysis. Jacobi von Wangelin et al. noticed that the borylation product 3a could also occurred in the absence of eosin Y, upon irradiation of a MeCN solution of the reactants with white LEDs [23][25]. Pleasingly, LAG

Photocatalyzed synthesis of isochromanones and isobenzofuranones under batch and flow conditions

• Manuel Anselmo,
• Lisa Moni,
• Hossny Ismail,
• Davide Comoretto,
• Renata Riva and
• Andrea Basso

Beilstein J. Org. Chem. 2017, 13, 1456–1462, doi:10.3762/bjoc.13.143

• reagents were supplied by the same syringe, which was kept shielded from the light source. In fact, we verified that no reaction was taking place in the dark, even prolonging the experiment for several hours. Although in the past we observed improvements in yields and purities switching from batch to flow

Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates

• Juraj Dobiaš,
• Marek Ondruš,
• Gabriela Addová and
• Andrej Boháč

Beilstein J. Org. Chem. 2017, 13, 1350–1360, doi:10.3762/bjoc.13.132

• starting from the same o-phenylenediamines and activated 4-chlorobenzoylpyruvates (ester or acid) enabling switching of 3,4-dihydroquinoxalin-2(1H)-one regioselectivity in a predictable manner. For comparison, all regioselective cyclocondensations were performed with the same standardized conditions (DMF

• , etc.). Therefore, we concluded that switching in regioselectivity (from native SYN to ANTI) could be a matter of DMAP activation of the acyl group in 12a. The above controlled ANTI cyclocondensation (88/12) performed in the presence of DMAP enabled us to obtain pure 17d (ANTI) regioisomer in a 36

• ), 22g is the same as 23g and no SYN/ANTI regioisomerism exists. The regioselective syntheses of both quinoxalin-2(1H)-ones 27 (ANTI) and 26 (SYN). The selective synthesis of substituted quinoxalin-2(1H)-ones 31 from 28 via three reaction steps. Regioselectivity switching based on carbonyl activation of

Towards open-ended evolution in self-replicating molecular systems

• Herman Duim and
• Sijbren Otto

Beilstein J. Org. Chem. 2017, 13, 1189–1203, doi:10.3762/bjoc.13.118

• . Switching between these two states can be achieved by applying external stimuli in the form of heat or the addition of decomposing agents. The switchable behavior and memory of such a self-replicating system constitute an exciting step, moving systems of self-replicating molecules away from equilibrium

G-Protein coupled receptors: answers from simulations

• Timothy Clark

Beilstein J. Org. Chem. 2017, 13, 1071–1078, doi:10.3762/bjoc.13.106

• with what is already available, it reuses successful designs again and again in slightly modified forms. This is the case for the most common means of communicating across cell walls in eukaryotes, G-protein coupled receptors (GPCRs). GPCRs span the cell membrane and generally complex switching ligands

• , H2-H3; EL2, H4-H5 and EL3, H6-H7). The extracellular loops are often involved in ligand recognition and binding, whereas the intracellular ones interact with the IBPs, usually a G-protein. The activation process involves switching of the binding on the intracellular side of the receptor, as outlined

• crystal-packing forces are large enough to change the induction state of the tetracycline repressor [26]. GPCR simulations often also show geometric rearrangements after several hundred nanoseconds, which suggests that the simulation is perhaps switching to a conformation closer to the biologically

A strategic approach to [6,6]-bicyclic lactones: application towards the CD fragment of DHβE

• Tue Heesgaard Jepsen,
• Emil Glibstrup,
• François Crestey,
• Anders A. Jensen and
• Jesper Langgaard Kristensen

Beilstein J. Org. Chem. 2017, 13, 988–994, doi:10.3762/bjoc.13.98

• attempted functionalization by treatment with n-BuLi and quenching with ethyl chloroformate led to a complex mixture of products; the same trend was also observed when switching to LDA as the base. When LiHMDS was applied in this reaction a double addition of ethyl formate took place giving rise to

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• tank reactor, adding a highly reactive reagent to the reactor, etc.), shut-down (viz. stopping the reaction, giving rapid cooling to the reaction mixture, etc.), change-over (viz. switching from reactant to solvent, changing or recovering the catalyst activity, etc.), override and emergency situations

Chemoselective synthesis of diaryl disulfides via a visible light-mediated coupling of arenediazonium tetrafluoroborates and CS₂

• Jing Leng,
• Shi-Meng Wang and
• Hua-Li Qin

Beilstein J. Org. Chem. 2017, 13, 903–909, doi:10.3762/bjoc.13.91

• undesired diphenyl polysulfides (Table 2, entry 4). Switching to DMSO as the solvent for the reaction afforded exclusively the desired product 3a in excellent yield (88%, Table 2, entry 6). Next, other sulfur sources were also examined, such as S8, NaSH, Na2S, Na2S2O3, Na2S2O4 and K2S2O8, however, none of

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

• Josef Jansa,
• Ramona Schmidt,
• Ashenafi Damtew Mamuye,
• Laura Castoldi,
• Alexander Roller,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2017, 13, 895–902, doi:10.3762/bjoc.13.90

• ratio is ≈6.6:1, for the 3-pyridinyl congener 1b it was found to be 187:1. Switching to the more polar solvent DMSO-d6 enhances the amount of the keto form to ≈3% (ratio 35:1). The enol forms of compounds 1 show the characteristically large chemical shifts for the OH proton (1a: 15.94 ppm, 1b: 16.52 ppm

• ) in condensed system 12 shows a characteristic upfield shift (δN-6 −176.2 ppm) compared to the ‘usual’ 15N NMR chemical shifts of 2-pyridinyl systems attached to pyrazole C-5 (δ ≈ −62 to −70 ppm). This is in perfect agreement with the ≈100 ppm upfield shift observed when switching from pyridine to

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• phenols from aryl bromides in the presence of CuI as catalyst in the mixed solvent of t-BuOH–DMSO–H2O at 120 °C (Scheme 9) [31]. Both electron-rich and electron-deficient aryl bromides were converted to the corresponding phenols in good to excellent yields. Under the optimum conditions, switching the base

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• component (Figure 1). Changing the phenylacetylene to other substituted arylacetylenes like p-tolylacetylene, o-bromophenylacetylene, p-bromophenylacetylene or switching from morpholine to other amines like piperidine, 4-benzylpiperidine and pyrrolidine also react smoothly to afford the corresponding

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

• Anastasia S. Kostyuchenko,
• Tatyana Yu. Zheleznova,
• Anton J. Stasyuk,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

• ). Moderate to large values of Stokes shifts are observed for compounds 15b–g originating from bond order switching (benzenoid to quinoid) in the excited state. Moderate values of Stokes shifts (0.52–0.63 eV) are observed for 15b–e and the Stokes shift increases with an increase of the aryl substituent size

3D printed fluidics with embedded analytic functionality for automated reaction optimisation

• Andrew J. Capel,
• Andrew Wright,
• Matthew J. Harding,
• George W. Weaver,
• Yuqi Li,
• Russell A. Harris,
• Steve Edmondson,
• Ruth D. Goodridge and
• Steven D. R. Christie

Beilstein J. Org. Chem. 2017, 13, 111–119, doi:10.3762/bjoc.13.14

• temperature and flow rate range (Figure 8). This produced the optimal reaction conditions as being 79.6 °C and 0.24 mL/min, which had a conversion of 56%. Again the system was able to identify the general trend towards higher yields at lower flow rates and higher temperatures. However, switching from

• place on the chip heater of a FlowSyn system by a metal clip. The system was allowed to reach temperature with solvent pumping throughout the system, before switching to a reagent flow. The product from each optimisation point was collected and analysed via UV–vis spectroscopy at a wavelength of 330 nm

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• the teicoplanin-related A47934 (sta) GPA biosynthetic machinery from Streptomyces toyocaensis [33] (Figure 1a) have revealed that the X-domain is in fact far from an innocent bystander during peptide oxidation and that switching this domain to other homologues can affect the selectivity of the Oxy

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• carbonyl moiety (Scheme 14). It must be noted that in these two examples the selectivity of the reaction could be tuned just by changing the catalyst precursor: by switching from the DBU-based IL to the DABCO–DMC IL, the selectivity changed from 82% for glycerol carbonate, to 83% for glycidol. In another

Ring-whizzing in polyene-PtL₂ complexes revisited

• Oluwakemi A. Oloba-Whenu,
• Thomas A. Albright and
• Chirine Soubra-Ghaoui

Beilstein J. Org. Chem. 2016, 12, 1410–1420, doi:10.3762/bjoc.12.135

• numerous [4][5][6][7][8][9] and have found use in synthetic strategies [10], switching devices [11][12][13] and energy storage [14][15]. Much less is known about the polyene–ML2 analogs. There are two classes of compounds; one set consists of d8 ML2 compounds [16][17][18][19] and the other, which we will

Molecular weight control in organochromium olefin polymerization catalysis by hemilabile ligand–metal interactions

• Stefan Mark,
• Hubert Wadepohl and
• Markus Enders

Beilstein J. Org. Chem. 2016, 12, 1372–1379, doi:10.3762/bjoc.12.131

• [8][9][10][11][12]. Examples are the switching from polymerization to trimerization selectivity [13] or the suppression of chain termination by weak interactions with fluorine substituents [14][15][16][17]. The interaction with fluorine atoms from fluorinated borate anions have also shown to play a

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• itaconate (50) in the presence of a rhodium(I) catalyst and (R)-BINAP ligand (43, Figure 2) [31]. During optimization they found that switching to potassium organotrifluoroborates from organoboronic acids was necessary to achieve high enantioinduction. Additionally, the enantioselectivity was highly

• -catalyzed enantioselective addition of benzylic thiols 104 to α,β-unsaturated ketones 105 (Scheme 25a) [50]. Interestingly, water was found to be the optimal solvent for this transformation, switching to organic solvents (CH2Cl2, THF, toluene) resulted in diminished reactivity and poor enantioselectivity

• could be achieved, the saturated ester product 146 could not be obtained in greater than 50% yield. In contrast, the unsaturated thioester 145 (X = S) provided the product in high yield and enantioselectivity. By switching to samarium catalyst (R)-Sm-143, the catalyst loading could be halved and a

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• redox bicycloisomerization reaction is compatible with a number of solvents that have vastly different steric profiles and dielectric constants. The nature of the solvent also had a significant impact on the enantiomeric ratios. Switching from THF to acetone, we observed a dramatic reversal in

• final product, as both (R)- and (S)-52 gave results that were almost identical to the racemic substrate (Table 8). Interestingly, however, switching to THF provided drastically different results. While redox bicycloisomerization of (R)-52 was very enantioselective, affording 53 in a 92.0 to 8.0