Homolytic substitution at phosphorus for C–P bond formation in organic synthesis

• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 1269–1277, doi:10.3762/bjoc.9.143

• more reactive than a phenyltelluranyl radical. Substitution of halides (X), carboxys (COOR), or carboxylates (OCOR) with phosphorus After scattered research efforts into the uncontrolled radical C–H phosphination under harsh reaction conditions [40], Barton elegantly devised radical decarboxylative

Use of 3-[¹⁸F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides

• Reik Löser,
• Steffen Fischer,
• Achim Hiller,
• Martin Köckerling,
• Uta Funke,
• Aurélie Maisonial,
• Peter Brust and
• Jörg Steinbach

Beilstein J. Org. Chem. 2013, 9, 1002–1011, doi:10.3762/bjoc.9.115

• corresponding potassium carboxylates under mild anhydrous conditions [37]. Its successful use for the acceleration of O-sulfonylations was recently described by Musachio et al. [38]. Conversion of [18F]10 with 4-nitroaniline in the presence of potassium trimethylsilanolate led to the formation of the desired

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

• Astrid Hoppe,
• Faten Sadaka,
• Claire-Hélène Brachais,
• Gilles Boni,
• Jean-Pierre Couvercelle and
• Laurent Plasseraud

Beilstein J. Org. Chem. 2013, 9, 647–654, doi:10.3762/bjoc.9.73

• under vacuo (method A) or by addition of NaBPh4 (method B). Possible catalytic and deactivation mechanisms are proposed. Keywords: aliphatic polyesters; green polymerization reaction; imidazolium-2-carboxylates; N-heterocarbene precursor; organocatalysis; Introduction Poly(ε-caprolactone) (PCL) and

• . In this quest and encouraged by our previous results, we chose to explore the potential of zwitterionic 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2, Figure 1). Indeed, methylimidazolium-2-carboxylates can be easily synthesized with high yields by the one-pot reaction of dimethyl carbonate

• concept was extended to the synthesis of aliphatic polycarbonates, involving the transesterification of DMC with linear alkane diols under solvent-free conditions, and based on a two-step polymerization process [50]. The high reactivity of imidazolium-2-carboxylates can be explained by their facile

A computational study of base-catalyzed reactions of cyclic 1,2-diones: cyclobutane-1,2-dione

• Nargis Sultana and
• Walter M. F. Fabian

Beilstein J. Org. Chem. 2013, 9, 594–601, doi:10.3762/bjoc.9.64

• bicyclic intermediate Int4 was found (Figure 4). Furthermore, this intermediate did not react to product P3 but instead through a concerted ring opening and proton transfer to P3a. The anticipated product P3 of path C is a γ-oxocarboxylate. Such γ-oxocarboxylic acids or carboxylates are prone to ring–chain

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate

• Mohammad Piltan,
• Loghman Moradi,
• Golaleh Abasi and
• Seyed Amir Zarei

Beilstein J. Org. Chem. 2013, 9, 510–515, doi:10.3762/bjoc.9.55

• ][26]. Ma and Yuan have reported the synthesis of pyrrolo[1,2-a]quinoxalin-4(5H)-ones by CuI/L-proline-catalyzed coupling of N-trifluoroacetyl-2-haloanilines with methyl pyrrole-2-carboxylates [27]. The development of more efficient methods for the preparation of these compounds is still an active

The multicomponent approach to N-methyl peptides: total synthesis of antibacterial (–)-viridic acid and analogues

• Ricardo A. W. Neves Filho,
• Sebastian Stark,
• Bernhard Westermann and
• Ludger A. Wessjohann

Beilstein J. Org. Chem. 2012, 8, 2085–2090, doi:10.3762/bjoc.8.234

• -terminus, which bears a N,N-dimethyl anthranilic amide moiety of still unknown biosynthetic origin. The previously reported synthetic strategy toward 1 was based upon a series of peptide couplings employing DCC reagent [5]. The necessity of difficult-to-perform peptide couplings with phenyl carboxylates

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• acetone-sensitised photodecarboxylation chemistry initially developed by Griesbeck [58] under batch conditions was suggested as being ideally suited to microflow conditions [59][60]. The chemistry involves the decarboxylative addition of potassium carboxylates to phthalimides, thus offering an alternative

• interest is the addition of carboxylates 46 to phthalimides 45 shown in Scheme 16. This reaction has also been compared for microflow and batch reactors for a number of substrates [61][62], and again, although residence times are lower under microflow conditions, productivity is higher for the batch

• completion [61]. In an extension of the above reactions, it was shown that α-thioalkyl-substituted carboxylates 50 could be added to phthalimides 45 in a microflow reactor (Scheme 16). Although the flow reaction proved successful, the final ratio of the desired product 51 to the unwanted reductive dimer 52

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Facile synthesis of functionalized tetrahydroquinolines via domino Povarov reactions of arylamines, methyl propiolate and aromatic aldehydes

• Jing Sun,
• Hong Gao,
• Qun Wu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2012, 8, 1839–1843, doi:10.3762/bjoc.8.211

• propiolates, and successfully established the imino Diels–Alder reaction with β-enamino ester as dienophile. This reaction provides a convenient and stereoselective procedure for the preparation of 2-aryl-4-arylamino-1,2,3,4-tetrahydroquinoline-3-carboxylates in satisfactory yields. Furthermore, we

Synthesis and ring openings of cinnamate-derived N-unfunctionalised aziridines

• Alan Armstrong and
• Alexandra Ferguson

Beilstein J. Org. Chem. 2012, 8, 1747–1752, doi:10.3762/bjoc.8.199

• -opening protocols have been developed, synthesis of the starting NH-aziridine-2-carboxylates is multistep and low-yielding. Synthetic routes include Gabriel–Cromwell addition of ammonia to an enoate [16][17]; epoxide opening with azide, followed by ring closure [19]; and a sequence of olefin

• aziridination methodology to access NH-aziridine-2-carboxylates in a single step from enoates. To the best of our knowledge, there exist only three examples of this transformation. Furukawa used diphenyl sulfilimine to form NH-aziridines from fumarate esters [32], and O-mesitylenesulfonylhydroxylamine (MSH) was

• moderate. Nonetheless, it is worth noting that this single-step transformation provides NH-aziridine-2-carboxylates in competitive or superior yields to alternative multistep methodologies. Having explored the scope of the aziridination, we were keen to investigate the susceptibility of our unactivated NH

Synthesis of conformationally restricted glutamate and glutamine derivatives from carbonylation of orthopalladated phenylglycine derivatives

• Esteban P. Urriolabeitia,
• Eduardo Laga and
• Carlos Cativiela

Beilstein J. Org. Chem. 2012, 8, 1569–1575, doi:10.3762/bjoc.8.179

• phenyl ring, and the corresponding synthesis of a new family of orthopalladated complexes [12]. The carbonylation of these compounds allows for a general synthesis of methyl (1H)-isoindolin-1-one-3-carboxylates under very mild reaction conditions, regardless of whether the substituents at the aryl ring

• reactivity found for 1, and shown in Scheme 3, when compared to related Pd complexes previously reported by us [12], resumed in Scheme 1. Therefore, the synthesis of the methyl (1H)-isoindolin-1-one-3-carboxylates by carbonylation of [Pd(μ-Cl)(C6H4CH(CO2Me)NH2-2)]2 occurs by C–N coupling, irrespective of the

• carbonylation reaction. Synthesis of methyl (1H)-isoindolin-1-one-3-carboxylates by carbonylation of phenylglycine derivatives [12]. Synthesis and NMR characterization of orthometallated complex 3. Carbonylation of 1 to afford glutamate and glutamine derivatives 2a–j. Reaction of 1 and CO in CH2Cl2 [18

Synthesis of diverse indole libraries on polystyrene resin – Scope and limitations of an organometallic reaction on solid supports

• Kerstin Knepper,
• Sylvia Vanderheiden and
• Stefan Bräse

Beilstein J. Org. Chem. 2012, 8, 1191–1199, doi:10.3762/bjoc.8.132

• 10.3762/bjoc.8.132 Abstract The synthesis of diverse substituted indole structures on solid supports is described. The immobilization of nitrobenzoic acid onto Merrifield resin and the subsequent treatment with alkenyl Grignard reagents delivered indole carboxylates bound to solid supports. In contrast to

Synthesis and anion recognition properties of shape-persistent binaphthyl-containing chiral macrocyclic amides

• Marco Caricato,
• Nerea Jordana Leza,
• Claudia Gargiulli,
• Giuseppe Gattuso,
• Daniele Dondi and
• Dario Pasini

Beilstein J. Org. Chem. 2012, 8, 967–976, doi:10.3762/bjoc.8.109

• difunctional carboxylates. We deemed it to be very interesting to increase the availability of hydrogen-bond donors within the macrocycle cavity, and to unlock the hydrogen-bonding capability of the amide NHs to their full potential for anion recognition. The former could in principle be achieved by unmasking

• insertion of either glutarate or succinate. In fact, the calculated dimensions of the two carboxylates are 5.3 Å for succinate and 6.5 Å for glutarate, considering their fully extended conformation. These data rationalize the preference shown in the case of macrocycle 12 for succinate; in detail, they

Cyanoethylation of the glucans dextran and pullulan: Substitution pattern and formation of nanostructures and entrapment of magnetic nanoparticles

• Kathrin Fiege,
• Heinrich Lünsdorf,
• Sevil Atarijabarzadeh and
• Petra Mischnick

Beilstein J. Org. Chem. 2012, 8, 551–566, doi:10.3762/bjoc.8.63

• ) decreased, with the maximum being shifted to higher wavenumbers (→ less hydrogen bonding). No side products, such as amides or carboxylates (as hydrolysis products of nitrile groups), or only traces thereof, were observed [21]. ATR–IR spectra of native dextran and the cyanoethyl ethers are shown in Figure 2

• isolated yields in the range from 72 to 86% were achieved (Table 1). The DS values strongly increased upon the addition of acetone as a solubility mediator (CED-2 and CEP-2). No side products, such as amides or carboxylates, or only traces thereof, were detectable for the CE glucans, as proved by IR and

N-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis

• Rob De Vreese and
• Matthias D’hooghe

Beilstein J. Org. Chem. 2012, 8, 398–402, doi:10.3762/bjoc.8.43

• reaction was performed by using a rather strong base (KHMDS, Et3N) to deprotonate the carbene precursor, which led to the formation of a weak Brønsted acid with low yields and poor selectivities as a consequence. The use of weaker bases (carboxylates) resulted in stronger conjugate acids capable of

Syntheses and applications of furanyl-functionalised 2,2’:6’,2’’-terpyridines

• Jérôme Husson and
• Michael Knorr

Beilstein J. Org. Chem. 2012, 8, 379–389, doi:10.3762/bjoc.8.41

• fact, the furan ring can readily undergo oxidative cleavage under various conditions, thus providing an interesting route to carboxylates [35]. In the case of tpys, oxidation of the furanyl ring was performed by using potassium permanganate in a basic reaction medium, followed by acidification to

NMR studies of anion-induced conformational changes in diindolylureas and diindolylthioureas

• Damjan Makuc,
• Jennifer R. Hiscock,
• Mark E. Light,
• Philip A. Gale and
• Janez Plavec

Beilstein J. Org. Chem. 2011, 7, 1205–1214, doi:10.3762/bjoc.7.140

• . Interestingly, negligible deshielding of H2β in 3 was observed and this suggests that the amide protons do not participate in the interaction with acetate and benzoate (Figure 7b). The observed Δδ values support the idea that carboxylates were strongly bound to the urea H7α protons which prevented interaction

• of chloride anions (Figure 7c). Considerable deshielding of H7α protons in 4 by up to 2.3 ppm in the 4·AcO− and 4·BzO− complexes suggested that the major interactions between carboxylates and receptor 4 occurred at the ureido functionality (Figure 7c). The conformational properties of the 4·AcO– and

Microphotochemistry: 4,4'-Dimethoxybenzophenone mediated photodecarboxylation reactions involving phthalimides

• Oksana Shvydkiv,
• Kieran Nolan and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2011, 7, 1055–1063, doi:10.3762/bjoc.7.121

• photostable and could be reisolated almost quantitatively during chromatography. Photodecarboxylative additions Phthalimides can be efficiently alkylated by photodecarboxylation of carboxylates and this methodology has emerged as a powerful alternative to Grignard additions [46][47][48]. In contrast to the

• . Alternatively, back electron transfer (BET) and protonation generates the simple decarboxylation products 2 and 5. Path A thus mirrors the mechanism proposed for acetone sensitization [43]. In contrast to carboxylates (for MeCO2− calc. EOx = 1.54 V in MeCN versus SCE), thioethers (for Me2S: EOx = 1.23 V versus

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• ]. This made the methodology useful for the synthesis of enantiomerically pure trans- and cis-1,3-dimethylisochromans starting from a single planar chiral chromium complex. 2.3 Carboxylates as nucleophiles Seraya has reported the gold-catalyzed rearrangement of cyclopropenylmethyl acetates as a route to

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• into the angular triquinane ventricosene in six steps (Scheme 23). 6 Ring expansions involving propargyl acyloxy rearrangements Propargyl carboxylates 80 can be π-activated by gold towards 1,2-acyloxy migration and/or [3,3]-sigmatropic rearrangement. Two different, but mechanistically related

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• proceed through ring-opening and intramolecular Friedel–Crafts cyclization have been studied using 3-aryl-cyclopropene-3-carboxylates. However, for these latter substrates, the carbonyl group can also play the role of a nucleophile and compete with the aryl group. Nucleophilic addition of carbonyl groups

• in competition with Friedel–Crafts reactions Besides the gold-catalyzed intermolecular addition of alcohols to cyclopropenes, Lee et al. investigated the behaviour of methyl 3-arylcyclopropen-2-yl carboxylates to ascertain whether the organogold species resulting from the ring-opening in the presence

• (MeCN)2 as catalysts [34]. Rearrangement of cyclopropenylmethyl acetates Propargylic carboxylates have proven to be particularly interesting substrates in gold-catalyzed reactions that have led to the development of useful synthetic processes relying on 1,3- or 1,2-acyloxy migration as the key step

Regioselective ester cleavage during the preparation of bisphosphonate methacrylate monomers

• Kamel Chougrani,
• Gilles Niel,
• Bernard Boutevin and
• Ghislain David

Beilstein J. Org. Chem. 2011, 7, 364–368, doi:10.3762/bjoc.7.46

• residual HBr. The next challenge was to cleave the trimethylsilyl phosphonates selectively, without affecting alkyl carboxylates, under controlled conditions of both temperature and solvent [23] since alkyl esters including acrylate or methacrylate esters are sensitive to hydrolytic conditions [29

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• . Direct irradiation of the ureido-substituted derivative induces a di-π-methane rearrangement to the corresponding dibenzosemibullvalene derivative, whereas the thioureido-substituted derivative is almost photoinert. Complexes of the latter derivative with chloride, carboxylates, or sulfonate anions

• 4, self-quenching can only take place in a bimolecular process, which is negligible at the low concentration employed in these experiments. It was demonstrated that the complexation of chiral carboxylates by the ureido substituents of the dibenzobarrelene derivative 1h may be employed, in principle

• the association of chiral carboxylates with 1h induces a stereoselective DPM rearrangement. So far, the selectivities are very low; however, these observations demonstrate that anion-controlled stereoselective DPM rearrangements may be accomplished in principle. Therefore, it is proposed that this

Fluorometric recognition of both dihydrogen phosphate and iodide by a new flexible anthracene linked benzimidazolium-based receptor

• Kumaresh Ghosh and
• Debasis Kar

Beilstein J. Org. Chem. 2011, 7, 254–264, doi:10.3762/bjoc.7.34

• [22] groups are well established. In addition, the use of the benzimidazolium motif [23][24] in anion recognition is also known. During the course of our work on anion recognition, we used this motif along with the other functionalities for selective recognition of carboxylates, and dihydrogen

Olefin metathesis in nano-sized systems

• Didier Astruc,
• Abdou K. Diallo,
• Sylvain Gatard,
• Liyuan Liang,
• Cátia Ornelas,
• Victor Martinez,
• Denise Méry and
• Jaime Ruiz

Beilstein J. Org. Chem. 2011, 7, 94–103, doi:10.3762/bjoc.7.13

• produce dendrimers whose tethers were terminated by carboxylic acid groups (Scheme 4 and Scheme 5). The corresponding carboxylates are water-soluble. Higher-generation dendrimers with carboxylic acid termini have been synthesized similarly [43][44]. Other attempts have been reported in the literature for