Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• acid nanoparticles (ASA NPs) proved to be efficient under neat conditions for the synthesis of 1-amidoalkyl-2-naphthols [19]. Zali et al. carried out this synthesis applying nano-sulfated zirconia [20], Borhade et al. used PbS nanoparticles [21], while Safari et al. applied magnetic-nanoparticle

• naphthoxazino-isoquinoline derivatives 43 under neat conditions staring from 1-aminoalkyl-2-naphthols and 6,7-dimethoxy-3,4-dihydroisoquinoline was observed [79]. At the same time, Osyanin et al. reported the same reaction extended by various substituted aminonaphthols [80]. Achieving the syntheses in ethanol

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• . This transformation is perhaps similar to acetal hydrolysis in neat water under microwave irradiation [41]. Because of this efficient process, compound 11 was isolated in one synthetic operation in 80% yield from amine 9. In the last step, precursor 11 reacted with either amine (R,R)-12 or (S,S)-12, to

Continuous-flow retro-Diels–Alder reaction: an efficient method for the preparation of pyrimidinone derivatives

• Imane Nekkaa,
• Márta Palkó,
• István M. Mándity and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2018, 14, 318–324, doi:10.3762/bjoc.14.20

• selected to comprise molecules where good (>80%), medium (70–80%) and no conversion was observed under batch rDA conditions. Batch reactions were carried out by the following ways: heating under neat conditions, refluxing in solvents having a high boiling point [chlorobenzene (CB) or 1,2-dichlorobenzene

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• groups on the 9,9-dimethyl-9,10-dihydroacridine units, this molecule proved to be also nearly insensitive to the concentration, showing an emission maximum for the neat film at 470 nm which is almost similar to that obtained for a 10 wt %-doped mCP film (462 nm where mCP stands for m-bis(N-carbazolyl

The synthesis of the 2,3-difluorobutan-1,4-diol diastereomers

• Robert Szpera,
• Nadia Kovalenko,
• Kalaiselvi Natarajan,
• Nina Paillard and
• Bruno Linclau

Beilstein J. Org. Chem. 2017, 13, 2883–2887, doi:10.3762/bjoc.13.280

• purification was required, which was convenient on scale. The reaction of (±)-trans-2 with neat Et3N·3HF at 120 °C for 16 h led, after aqueous work-up, to (±)-anti-3 in high diastereomeric purity (see Supporting Information File 1). The 19F shift of −195.3 ppm is different compared to that of (±)-syn-3 (−204.4

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• , 134.6, 136.8; 19F NMR (470 MHz, CDCl3) δ 124.7 (br s); IR (neat): 3068, 1489, 1454, 1126, 1147, 1097, 964, 850, 742, 696, 592 cm−1; HRMS–EI (m/z): [M]+ calcd for C21H15F2I, 432.0186; found: 432.0166. Typical procedure for the iodoarylation of 2-(3,3-difluoroallyl)biaryls 5: To a HFIP (2.5 mL) and

• ), 134.6, 138.6 (dd, JCF = 5 Hz), 140.3; 19F NMR (470 MHz, DMSO-d6, 120 °C) δ 72.3 (d, JFF = 236 Hz, 1F), 86.5 (d, JFF = 236 Hz, 1F); IR (neat): 3068, 3030, 1450, 1149, 1055, 989, 752, 598 cm–1; HRMS–EI (m/z): [M]+ calcd for C15H11F2I, 355.9873; found: 355.9866. ORTEP diagram of 2a with 50% ellipsoid

A concise flow synthesis of indole-3-carboxylic ester and its derivatisation to an auxin mimic

• Marcus Baumann,
• Ian R. Baxendale and
• Fabien Deplante

Beilstein J. Org. Chem. 2017, 13, 2549–2560, doi:10.3762/bjoc.13.251

• . For all compounds DEPT-135, COSY, HSQC, and HMBC were run and used in the structural assignment. IR spectra were recorded neat (ATR sampling) with the intensities of the characteristic signals being reported as weak (w, <20% of tallest signal), medium (m, 20–70% of tallest signal) or strong (s, >70

• 162.8 (C), 147.6 (C), 133.3 (q, J = 35 Hz, C), 132.4 (CH), 131.0 (q, J = 4 Hz, CH), 128.9 (C), 123.7 (q, J = 4 Hz, CH), 122.2 (q, J = 273 Hz, C), 113.8 (C), 64.4 (CH2), 41.2 (CH), 13.9 (CH3); 19F NMR (376 MHz, CDCl3) δ −63.2; IR (neat) ν/cm−1: 3092 (w), 2925 (w), 1732 (m), 1537 (m), 1502 (m), 1357 (m

• 164.4 (C), 135.8 (d, J = 3 Hz, CH), 128.7 (C), 125.4 (q, J = 273 Hz, C), 123.3 (q, J = 34 Hz, C), 121.75 (CH), 118.0 (q, J = 4 Hz, CH), 117.6 (C), 110.3 (q, J = 4 Hz, CH), 107.5 (C), 59.8 (CH2), 14.9 (CH3); 19F NMR (376 MHz, DMSO-d6) δ −59.3; IR (neat) ν/cm−1: 3196 (m), 1667 (s), 1514 (m), 1440 (m

Exploring mechanochemistry to turn organic bio-relevant molecules into metal-organic frameworks: a short review

• Vânia André,
• Sílvia Quaresma,
• João Luís Ferreira da Silva and
• M. Teresa Duarte

Beilstein J. Org. Chem. 2017, 13, 2416–2427, doi:10.3762/bjoc.13.239

• compounds to promote a reaction, by inducing the breaking/forming of covalent or supramolecular bonds [1][2]. There are different approaches towards mechanochemistry. The most direct is neat grinding (NG), in which the reagents are ground together without the addition of any solvent or other additive [3

Comparative profiling of well-defined copper reagents and precursors for the trifluoromethylation of aryl iodides

• Peter T. Kaplan,
• Jessica A. Lloyd,
• Mason T. Chin and
• David A. Vicic

Beilstein J. Org. Chem. 2017, 13, 2297–2303, doi:10.3762/bjoc.13.225

• until 2011. Trifluoromethylations with [(PPh3)3CuCF3] are only efficient when the reactions are performed in neat aryl iodode [14]. Less side-products and higher yields are observed for trifluoromethylations with [(PPh3)3CuCF3] when dtbpy (dtbpy = 4,4′-di-tert-butylbipyridine) is added to reaction

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

• Patrick A. Julien,
• Ivani Malvestiti and
• Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

• from a set of triplicate measurements. Variation close to the onset of milling may be due to poor initial homogeneity of the sample. The reproducibility of varying milling frequency on the neat mechanochemical condensation of benzil and o-phenylenediamine, as measured by triplicate experiments. The

Synthesis of 2-aminosuberic acid derivatives as components of some histone deacetylase inhibiting cyclic tetrapeptides

• Shital Kumar Chattopadhyay,
• Suman Sil and
• Jyoti Prasad Mukherjee

Beilstein J. Org. Chem. 2017, 13, 2153–2156, doi:10.3762/bjoc.13.214

• ethyl acetate in hexane to provide the coupled product as colorless viscous liquid. (S,E)-1-tert-Butyl 8-methyl 7-(tert-butoxycarbonylamino)oct-2-enedioate (14a) Colourless liquid. Yield: 148 mg, 83%; [α]D25 +12.60 (c 1.00, CHCl3); IR (neat): 3363, 2978, 2933, 1715, 1652, 1505, 1367, 1164 cm−1; 1H NMR

Peptide synthesis: ball-milling, in solution, or on solid support, what is the best strategy?

• Ophélie Maurin,
• Pascal Verdié,
• Gilles Subra,
• Frédéric Lamaty,
• Jean Martinez and
• Thomas-Xavier Métro

Beilstein J. Org. Chem. 2017, 13, 2087–2093, doi:10.3762/bjoc.13.206

• coupling products in satisfying purity and in isolated yields ranging from 78 to 89%. Of note, it was observed previously under similar reaction conditions that the absence of EtOAc as liquid grinding assistant (neat grinding) could lead to inhomogeneity of the reagents distribution inside the ball-mill

One-pot multistep mechanochemical synthesis of fluorinated pyrazolones

• Joseph L. Howard,
• William Nicholson,
• Yerbol Sagatov and
• Duncan L. Browne

Beilstein J. Org. Chem. 2017, 13, 1950–1956, doi:10.3762/bjoc.13.189

• ; mechanochemistry; multistep; solid-state synthesis; Introduction Mechanochemical methods are emerging as an alternative approach to traditional solvent-based reactions for chemical synthesis. Under mechanochemical conditions reactions are performed between neat reagents and do not require a solvent. Processing

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

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

• were screened with electron-donating and electron-withdrawing groups attached to aromatic rings. The reactions were performed in a 1:1 stoichiometry by manual grinding in a mortar and by automated ball milling in a laboratory mixer mill. Also, the performance of solvent-free or neat grinding was

• )-(+)-1,1′-binaphthyl-2,2′-diamine in a stoichiometric ratio. The corresponding chiral bis-thiourea organocatalysts were isolated in ≥99% yields after only 20 minutes (60 min in the case of binaphthylthiourea) of neat grinding or LAG. Interestingly, while the solution synthesis of (1R,2R)-8 in THF followed

• dithiocarbamate salt 23 (Scheme 8a). In comparison with 24 h reactions carried out in solvents (CH2Cl2, THF, acetone, methanol, DMF, DMSO or neat CS2), the mechanochemical synthesis was rapid and furnished electron-rich isothiocyanates in high yields in 40–45 minutes (e.g., 24a–c). On the other hand, anilines

An efficient Pd–NHC catalyst system in situ generated from Na₂PdCl₄ and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

• Nan Sun,
• Meng Chen,
• Liqun Jin,
• Wei Zhao,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168

• obviously better than that of NaOH. To clarify that this improvement might be due to the generation of EtOH and t-BuOH from the hydrolysis of NaOEt and NaOt-Bu in water, we then studied the effect of EtOH and t-BuOH on the reaction. In contrast to the reaction in neat water with NaOH as base, the yields of

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• involved the coordination of L2RuCl2 (L = p-cumene) with the more basic quinazolinone nitrogen to form complex K, which underwent β-H elimination to afford quinazolinone L and (RuLCl)-H, which further reduced to Ru0. Oxygen revived active RuI from Ru0. The neat step involved cross coupling/annulation of L

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• °, 33°, 38°, 60°, indexing to (003), (006), (009), (015), (110) reflections, which indicates the highly neat degree and well-crystallinity structure of LDH materials without phase impurities apparent. Moreover, the MgAl-LDHs presents an interlayer distance of 0.82 nm from the basal spacing of d003

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Phenylsilane as an effective desulfinylation reagent

• Wanda H. Midura,
• Aneta Rzewnicka and
• Jerzy A. Krysiak

Beilstein J. Org. Chem. 2017, 13, 1513–1517, doi:10.3762/bjoc.13.150

• excess of phenylsilane under neat reaction conditions in the presence of a catalytic amount of KOH. It appeared that results of this reaction strongly depended on the relative position of particular substituents [21]. For compounds 1 and 2 the treatment with phenylsilane caused, as expected, in a

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

• . Simultaneous neat grinding/irradiation of the reactants and the photocatalyst led to the formation of boronates in a molten state. On the other hand, the catalyst-free liquid-assisted grinding/irradiation reaction also led to product formation, featuring a direct photolysis pathway facilitated by substrate

• underexplored [14], despite photocatalysis could clearly benefit from the excellent mixing under neat or liquid-assisted grinding (LAG) [15] conditions. Additionally, in contrast to solution-based methods, reactions by milling do not suffer from solubility restrictions due to the possibility to bring reactants

• yielded the same negative result proving that ambient light did not mediate the photoredox catalytic borylation reaction under mechanochemical conditions (Table 1, entry 3). Furthermore, neat grinding of a catalyst-free mixture of 1a and 2 under blue LEDs (light-emitting diodes) light did not afford the

Synthesis of the heterocyclic core of the D-series GE2270

• Christophe Berini,
• Thibaut Martin,
• Pierrik Lassalas,
• Francis Marsais,
• Christine Baudequin and
• Christophe Hoarau

Beilstein J. Org. Chem. 2017, 13, 1407–1412, doi:10.3762/bjoc.13.137

• the neat synthesis of GE2270 central core in 33% yield over a 4-step sequence (Figure 1) including three Negishi and Stille cross-coupling reactions to achieve the direct introduction of mono- and dithiazolyl units to a 2,3,6-trihalopyridine [17]. The strategy has then extended to the total synthesis

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

• Desirée Leistenschneider,
• Nicolas Jäckel,
• Felix Hippauf,
• Volker Presser and
• Lars Borchardt

Beilstein J. Org. Chem. 2017, 13, 1332–1341, doi:10.3762/bjoc.13.130

• done in 1 M TEA-BF4 in acetonitrile (ACN) and neat EMIM-BF4 as an ionic liquid. Since ionic liquids show a lower ion mobility as compared to aqueous or organic electrolytes, a well-connected transport pore system is of particular importance to guarantee a fast ion transport and should result in better

• cyclic voltammograms (CVs) in both electrolytes (Figure 7A,B) [53]. At low current rates, the material shows good specific capacitance (Table 2) of 138 F g−1 in neat EMIM-BF4 and 98 F g−1 in 1 M TEA-BF4 (ACN) determined by galvanostatic cycling with potential limitation at 0.1 A g−1. These values are

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• University, Universitetskaya nab., 7/9, Saint Petersburg, 199034, Russia Institute of Synthetic Rubber, Gapsalskaya str., 1, Saint Petersburg, 198035, Russia 10.3762/bjoc.13.89 Abstract The metal-free reaction of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles with arenes in neat triflic acid (TfOH, CF3SO3H

• protonation of the C=C bond of 1a in H2SO4 does not take place even at elevated temperature (75 °C, see Table 2, entry 1). Also, Lewis acids such as AlCl3 and AlBr3 are not effective in this transformation (Table 2, entries 2 and 3). The best results were obtained in neat TfOH. The substituents present in the

• temperature (Table 2, entries 13, 16, 27, 28, and 30). Increasing the acidity of the reaction medium promotes the protonation of deactivated oxadiazoles. Thus, compound 1b in the system TfOH-SbF5 (20 mol %) reacted with benzene within 0.5 h at room temperature (Table 2, entry 9), but in less acidic neat TfOH

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

• Vinila N. Viswanathan,
• Arun D. Rao,
• Upendra K. Pandey,
• Arul Varman Kesavan and
• Praveen C. Ramamurthy

Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87

• , 1,2-difluorobenzene was reacted with trimethylsilyl chloride in the presence of lithium diisopropylamide to afford the 1,4-disilylated intermediate 4 and bromination of the latter compound in neat bromine afforded the desired 1,4-dibromo-2,3-difluorobenzene (5). Nitration of 5 by treatment with fuming

Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

• Loïc Pantaine,
• Vincent Humblot,
• Vincent Coeffard and
• Anne Vallée

Beilstein J. Org. Chem. 2017, 13, 648–658, doi:10.3762/bjoc.13.64

• ) δ 20.2 (2C), 118.6 (4C), 119.1 (4C), 129.2 (2C), 129.4 (4C), 130.5 (4C), 132.3 (2C), 135.2 (2C), 138.6 (2C); IR (neat): 3291, 3031, 2918, 2857, 1449, 1329, 1150, 903, 807, 622, cm-1; HRMS–ESI (m/z): [M + H]+ calcd for C26H27N4O4S4 587.0915, found: 587.0920. Monolayer preparation A solution of 4