Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs

• Arne Klinkebiel,
• Ole Beyer,
• Barbara Malawko and
• Ulrich Lüning

Beilstein J. Org. Chem. 2016, 12, 2267–2273, doi:10.3762/bjoc.12.219

• the Suzuki–Miyaura coupling [11]. A retrosynthetic analysis (Figure 3) of extended mono-functionalized triazinetricarboxylic acids 2 calls for tris(4-bromoaryl)-1,3,5-triazines 3 and boronic acids 4 with an additional carboxylic acid functionality. The respective methyl carboxylate of boronic acid 4

• ) MeOH/H2SO4, MeOH, 16 h, reflux, 94%, c) Me2SO4, K2CO3, acetone, 3 h, reflux, quant., d) MeI, K2CO3, DMF, 16 h, room temperature, 83%, e) NaOH, H2O, MeOH, 6 h, room temperature, 66%, f) SOCl2, DMF (cat.), 2 h, reflux, not isolated. Triple Suzuki–Miyaura coupling between tribromotriazines 3 and boronic

• acid 15 and subsequent hydrolyses of the esters 16. Conditions: a) Pd(PPh3)4, K3PO4, dioxane, H2O, 48 h, reflux, 16b: 90%, 16c: 73%, b) Pd/C, H2, 5 bar, CH2Cl2, 5 d, room temperature, 16d: 77%. c) 17b: LiOH/H2O/dioxane, 48 h, room temp, 96%; 17c: LiOH/H2O/THF, 24 h, 60 °C, quant.; 17d: H2O/THF, 24 h

Catalytic Chan–Lam coupling using a ‘tube-in-tube’ reactor to deliver molecular oxygen as an oxidant

• Carl J. Mallia,
• Paul M. Burton,
• Alexander M. R. Smith,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1598–1607, doi:10.3762/bjoc.12.156

• boronic acid used was decreased to 1.4 equiv and 1.1 equiv, respectively (entries 12 and 13, Table 1). Changing the temperature from 20 °C to 50 °C did not greatly affect the yields obtained, with 40 °C giving the most promising result (entries 14–16, Table 1). However, it was observed that less

• acetate. The amount of triethylamine was not varied as its quantity was required to ensure the boronic acid remained soluble in the dichloromethane solvent. To determine the time needed to reach steady state in the reactor, samples were periodically collected (every 2 min via an autosampler) and analysed

• acid. A column of QP-DMA, a polymer-supported tertiary amine base, was placed in-line after the “tube-in-tube” reactor (Figure 1). It was found that this was sufficient to remove the majority of boronic acid without affecting the yield of the product (Figure 3). Ultimately as the products were required

Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations

• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1170–1177, doi:10.3762/bjoc.12.112

• prepared by the methods described above are excellent and versatile precursors for transition-metal-catalyzed coupling reactions [32][53][54][55][56][57]. Standard conditions for a Suzuki coupling smoothly transform compound 5a and a boronic acid derivative into the expected 4-tolyl-substituted derivative

• 9 and the higher substituted precursor 5b was converted into compound 10 by employing an acetyl-substituted boronic acid derivate in very good yield (Scheme 5). Compound 10 was prepared in order to investigate its capability to form a C3-symmetric star-shaped product by cyclocondensation of the

The role of alkyl substituents in deazaadenine-based diarylethene photoswitches

• Christopher Sarter,
• Michael Heimes and
• Andres Jäschke

Beilstein J. Org. Chem. 2016, 12, 1103–1110, doi:10.3762/bjoc.12.106

• benzenesulfonyl chloride, resulting in a four-fold increased yield of 6 compared to the original route. The other part of the diarylethene, namely the cyclopentenyl bridge with the attached substituted thiophene ring was furnished as shown in Scheme 3 and activated as boronic acid pinacolate ester. Suzuki

• of the closed ring form was measured over 1 h. Synthesis of 7-deaza-2’-deoxyadenosine photoswitches with one and two methyl groups via Suzuki cross-coupling [45]. Optimized route for synthesis of 7-deaza-7-iodo-8-methyl-2’deoxyadenosine (9). Synthesis of the boronic acid pinacolate esters. Absorption

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• gave excellent selectivity at room temperature (Scheme 5). When this substrate was subjected to optimized conditions for the boronic acid C–H coupling, the corresponding singly ortho-arylated product was obtained in 97% yield solely as the 2-aryl isomer, as confirmed by 1H NMR and X-ray crystallography

• acidity of the metal center. This is a noteworthy advantage associated with the use of cationic palladium(II) catalysts. Finally, BQ oxidizes the Pd(0) that is reductively eliminated from the HPd(II)+BF4− formed to regenerate the active cationic palladium species Pd2+(BF4)2−. C–H boronic acid coupling

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

• Dariusz Błachut,
• Joanna Szawkało and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2016, 12, 835–845, doi:10.3762/bjoc.12.82

• %) as a co-solvent with toluene. On the other hand, the attempted coupling of compound 41 with 2-nitrophenylboronic acid and (2-chloro-6-methoxyphenyl)boronic acid failed. Despite more drastic conditions (xylene, DMF, 145 °C, 48 h, 8 mol % Pd(OAc)2/16 mol % S-Phos) any amount of 3,5-bis(2-nitrophenyl

• (41) and (2-methylphenyl)boronic acid (37) in dioxane in the presence of PdCl2(dppf) × CH2Cl2, K3PO4, at 65 °C, provided only a mixture of debrominated and dechloro/debrominated phenylpyridines with only little quantities of the desired products 70, and 68 (<5%), respectively (estimated by GC–MS

Iridium/N-heterocyclic carbene-catalyzed C–H borylation of arenes by diisopropylaminoborane

• Mamoru Tobisu,
• Takuya Igarashi and
• Naoto Chatani

Beilstein J. Org. Chem. 2016, 12, 654–661, doi:10.3762/bjoc.12.65

• ) complex with 1,3-dicyclohexylimidazol-2-ylidene is found to efficiently catalyze the borylation of arenes and heteroarenes. The resulting aminoborylated products can be converted to the corresponding boronic acid derivatives simply by treatment with suitable diols or diamines. Keywords: boronic acid; C–H

Self and directed assembly: people and molecules

• Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

• Supramolecular Chemistry was through the self-assembly of phospholipid membranes to form vesicles for which we were developing unimolecular and self-assembling transporter molecules. The next stage of my development as a scientist was in Japan with Seiji Shinkai where in a “Eureka” moment, the boronic acid

• of Victoria, I knew very little about Japan and almost-nothing about the Japanese Language. (Karate had taught me to count from 1 to 10). Having just finished a project with a lot of multistep synthesis, I was immediately drawn to projects as part of the boronic acid research group. The boronic acid

• fluorescent photoinduced electron transfer (PET) pH sensors developed by A. P. De Silva (Figure 3) [17] in order to develop a fluorescence sensor for saccharides [18]. Thus creating a system where the neighbouring nitrogen lowered the working pH of the boronic acid and provided a fluorescence signalling

Art, auto-mechanics, and supramolecular chemistry. A merging of hobbies and career

• Eric V. Anslyn

Beilstein J. Org. Chem. 2016, 12, 362–376, doi:10.3762/bjoc.12.40

• Inouye and Shinkai [60][61]. IDAs are now one of a handful of standard approaches to creating optical sensors [62]. Our group optimized the citrate receptor design by incorporating a single boronic acid (11) [63] and measured citrate in soda pops [64], vodkas [65], and most recently showed that such

• the boronic acid in a spatial manner to best complement the citrate “key” to the receptor “lock” (11). In other studies, using a lock and key design approach led to very selective and high affinity receptors for heparin [68][69] and 2,3-bisphosphoglycerate [70]. Although reading the label of a Fresca

N-Methylphthalimide-substituted benzimidazolium salts and PEPPSI Pd–NHC complexes: synthesis, characterization and catalytic activity in carbon–carbon bond-forming reactions

• Senem Akkoç,
• Yetkin Gök,
• İlhan Özer İlhan and
• Veysel Kayser

Beilstein J. Org. Chem. 2016, 12, 81–88, doi:10.3762/bjoc.12.9

• -butylphenylboronic acid which is a derivative of phenylboronic acid (Table 3, entries 5–8). All compounds were found to be very effective for this coupling reaction and the product yield was between 94–100%. The C–C bond formation of thianaphthene-2-boronic acid with 4-chloronitrobenzene using an in situ formed Pd

• demonstrated low activity in the coupling of thianaphthene-2-boronic acid with 4-chloronitrobenzene (Table 3, entries 9–12; Table 4, entries 9–12). In C–C bond-forming reactions of different substrates with 2,5-dimethoxyphenylboronic acid and thianaphthene-2-boronic acid, complex 7 was found to be a good

• bromidesa,b. Suzuki–Miyaura cross-coupling reaction of phenylboronic acid with aryl chloridesa,b. Suzuki–Miyaura cross-coupling reaction of boronic acid derivatives with aryl halidesa,b. Suzuki–Miyaura cross-coupling reaction of boronic acid derivatives with aryl chloridesa,b. Supporting Information

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• of CnFn+1Cu reagent were used. dPinacolboronate ester (Bpin) was used instead of boronic acid. eYield was determined by 19F NMR analysis using BTF as an internal standard. Trifluoromethylation with silylated hemiaminal of fluoral. Catalytic trifluoromethylation with a fluoral derivative. The scope of

Assembly of synthetic Aβ miniamyloids on polyol templates

• Sebastian Nils Fischer and
• Armin Geyer

Beilstein J. Org. Chem. 2015, 11, 2646–2653, doi:10.3762/bjoc.11.284

• ; boronic acid; miniamyloids; NMR spectroscopy; peptides; Introduction Aβ peptides spontaneously form amyloid fibrils which are a major component of Alzheimer plaques [1]. The cooperative thermodynamically-driven process of fibril formation has an induction period which depends on the conditions of amyloid

• concept of tailoring the length of the peptide boronic acid and a polyol template is shown in Figure 2. Results and Discussion The shortest known functional expansion of the amyloidogenic Aβ-peptide is the β-amyloid (17–21) Leu-Val-Phe-Phe-Ala [20] which was investigated as both a C-terminal 1 and as an N

• -terminal boronic acid 2. Peptide boronic acids of type 1 were synthesized on polymer-bound diethanolamine (PS-DEAM resin), according to the protocol in Supporting Information File 1, Figure S1 [21]. The electron-poor boronic acid 2, which was expected to be more reactive in boronic ester formation, was

Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides

• Hang Ren,
• Haoyun An,
• Paul J. Hatala,
• William C. Stevens Jr,
• Jingchao Tao and
• Baicheng He

Beilstein J. Org. Chem. 2015, 11, 2509–2520, doi:10.3762/bjoc.11.272

• . Suzuki coupling efficiency in DMF (entries 2 and 3, Table 1) was not as high as Stille coupling (entry 1, Table 1). Suzuki coupling of intermediate 26 with 1-naphthylboronic acid, pyridine-4-boronic acid, pyridine-3-boronic acid and 5-propynylpyridine-3-boronic acid (Method II) (entries 4, 6, 8, and 10

Comparison of the catalytic activity for the Suzuki–Miyaura reaction of (η⁵-Cp)Pd(IPr)Cl with (η³-cinnamyl)Pd(IPr)(Cl) and (η³-1-t-Bu-indenyl)Pd(IPr)(Cl)

• Patrick R. Melvin,
• Nilay Hazari,
• Hannah M. C. Lant,
• Ian L. Peczak and
• Hemali P. Shah

Beilstein J. Org. Chem. 2015, 11, 2476–2486, doi:10.3762/bjoc.11.269

• added 950 μL of a MeOH stock solution, containing 0.5263 M aryl chloride, 0.5525 M boronic acid, 0.5789 M KOt-Bu and 0.2632 M naphthalene. The vial was then heated using an aluminum block heater set to 25 °C. After thermal equilibration, the reaction was initiated via the addition of 50 μL of the

• needle. To the vial was added 950 μL of a MeOH stock solution, containing 0.5263 M aryl chloride, 0.5525 M boronic acid and 0.2632 M naphthalene. The vial was then heated using an aluminum block heater set to 25 °C. After thermal equilibration, the reaction was initiated via the addition of 50 μL of the

Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

• Takamichi Wakamatsu,
• Kazunori Nagao,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2015, 11, 2444–2450, doi:10.3762/bjoc.11.265

• acidic MeOH (vide infra). There was no reaction in the absence of a proton sourse. No hydroalkylation product at all could be found when alkyl-9-BBN 2a was replaced by (2-phenylethyl)boronic acid pinacolate ester; the substrates hardly reacted at all. A variety of β-disubstituted acrylates were

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF₅-substituted phenylboronic esters and iodobenzenes

• George Iakobson,
• Junyi Du,
• Alexandra M. Z. Slawin and
• Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

• %), LiOH·H2O (4 mmol), 1,4-dioxane (2 mL), water (1 mL), 3.5 h. Syntesis of boronic acid 8b and trifluoroborates 9. Reaction conditions for the synthesis of 8b: 2 (2 mmol), NaIO4 (8 mmol), THF (8 mL), H2O (2 mL), rt, 1 h. Reaction conditions for the synthesis of 9: 2 (2 mmol), KHF2 (10 mmol), MeOH (8 mL), H2O

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

• Clara Orofino-Pena,
• Diego Cortizo-Lacalle,
• Joseph Cameron,
• Muhammad T. Sajjad,
• Pavlos P. Manousiadis,
• Neil J. Findlay,
• Alexander L. Kanibolotsky,
• Dimali Amarasinghe,
• Peter J. Skabara,
• Tell Tuttle,
• Graham A. Turnbull and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2704–2714, doi:10.3762/bjoc.10.285

• . Finally, Suzuki coupling of the bromo compound T-B1Br with terfluorenyl boronic acid F3B was achieved in 21% yield. The boronic acid SiFB was synthesised using a previously published procedure [23]. The core precursor T-B0Br was synthesised in 63% yield by using NBS as the brominating reagent instead of

Exploration of C–H and N–H-bond functionalization towards 1-(1,2-diarylindol-3-yl)tetrahydroisoquinolines

• Michael Ghobrial,
• Marko D. Mihovilovic and
• Michael Schnürch

Beilstein J. Org. Chem. 2014, 10, 2186–2199, doi:10.3762/bjoc.10.226

• reaction. Formation of trimeric boronic acid anhydride was observed via GC–MS, a species less reactive in arylation reactions. When small amounts of water were added on purpose the reaction solution turned black immediately, most likely due to the formation of Pd black which is inactive in the present

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

• J. Alexander Willms,
• Rita Beel,
• Martin L. Schmidt,
• Christian Mundt and
• Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

• -bromophenol using a strategy reported by Diemer et al. [55]. Protection of the hydroxy group to yield 3 [56] was followed by Suzuki cross-coupling with commercial pyridine-4-boronic acid leading to 4. Subsequent deprotection led to 4-(pyridine-4-yl)phenol (5) (Scheme 2) [55]. The preparation of the charge

Clean and fast cross-coupling of aryl halides in one-pot

• Valerica Pandarus,
• Geneviève Gingras,
• François Béland,
• Rosaria Ciriminna and
• Mario Pagliaro

Beilstein J. Org. Chem. 2014, 10, 897–901, doi:10.3762/bjoc.10.87

• emerging as a promising tool for synthetic organic chemistry [9]. In this research context, we have recently described the heterogeneously catalyzed synthesis of boronic acid pinacol esters using a wide range of aryl chlorides, bromides and iodides and bis(pinacolato)diboron as borylating agent over the

• 0.2–0.3 mmol/g palladium loading, a high surface area and large accessible mesoporosity (300–650 m2/g, depending on the applied parameters of the sol–gel synthesis). The leach-proof and truly heterogeneous nature of SiliaCat DPP-Pd in the synthesis of boronic acid pinacol esters has been recently

• intermediate boronic acid pinacol ester. The overall process is described by Scheme 2. The SiliaCat DPP-Pd catalyst mediates the borylation and the subsequent Suzuki–Miyaura reaction in an elegant one-pot sequential synthesis. Hence, an aryl bromide is first converted into the boronic acid pinacol ester (step

Group-assisted purification (GAP) chemistry for the synthesis of Velcade via asymmetric borylation of N-phosphinylimines

• Jian-bo Xie,
• Jian Luo,
• Timothy R. Winn,
• David B. Cordes and
• Guigen Li

Beilstein J. Org. Chem. 2014, 10, 746–751, doi:10.3762/bjoc.10.69

• reported so far [14][15][16][17][18][19][20]. Among the resulting products from the above methods, (R)-(1-amino-3-methylbutyl)boronic acid served as the key mechanism-based pharmacophore in the anticancer drug Velcade, which was the first FDA approved proteasome inhibitor, and has been in clinical use for

• ) and the H-bonds between the molecules (right). Selected bond lengths [Å] and angle [o]: P1–O1 1.505, P1–N1 1.613, N1–H1, 0.957, B1–O2 1.368, the H-bond O1···H2 1.990; the angle of H bond N1–H1···O4 142.79. Previous work for (R)-(1-amino-3-methylbutyl)boronic acid synthesis. Synthesis of (R)-4 and

Synthesis of chiral N-phosphinyl α-imino esters and their application in asymmetric synthesis of α-amino esters by reduction

• Yiwen Xiong,
• Haibo Mei,
• Lingmin Wu,
• Jianlin Han,
• Yi Pan and
• Guigen Li

Beilstein J. Org. Chem. 2014, 10, 653–659, doi:10.3762/bjoc.10.57

• esters [6][7][8][9][10]. Up to now, a series of nucleophilic substrates have been reported to react with α-imino esters, such as enamine [11][12][13][14], carbamate ammonium ylide [15], 1,3-dipolar cycle [16], boronic acid [17], acetylide [18], proparygylic anion [19] and ketene silyl acetal [20]. These

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• . NaOMe reacts with the ligand precursor 26 and forms an N-heterocyclic carbene. The method was tested also with Garner’s aldehyde and two different boronic acid derived nucleophiles (R = Ph or 1-octenyl). High anti-selectivity was observed. With the in situ formed phenyl nucleophile the selectivity was

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• presence of arylboronic acid (iv and v). The latter evidence prompted the authors to conclude that the aryl group was transferred from the boronic acid and not from the gold complex (i.e. the phenyl group on the in situ formed PPh3AuPh complex acts as a spectator in the process). Based on such observations

• oxygen- and nitrogen-containing coupling partners [83][84]. Interestingly, due to the employment of Selectfluor as a stoichiometric exogenous oxidant, the addition of basic activators for silane reagents were not required. The ready availability of silane precursors, with respect to boronic acid