From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• “coated” with water-solubilizing carboxylic acids/carboxylates to bestow good water solubility under basic conditions, and; 2) possessed a rim of hydrophobicity around the entrance to its interior hydrophobic pocket. We envisioned that driven by the hydrophobic effect this host would readily form 1:1

• carboxylates have proven to be one of the most reliable approaches to date, it is not the only approach. For example, working with Scott Grayson across town at Tulane University we successfully formed the dendrimer–coated host shown in Figure 8 [36], as well as wide series of polymer coated derivatives coupled

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

• -scale operation. On the other hand, economical and useful perfluoroalkylated carboxylic acid derivatives, such as perfluoroalkylated carboxylates (CnF2n+1CO2Na or CnF2n+1CO2K), halodifluoroacetates (XCF2CO2R), perfluoroalkyl carboxylates (CnF2n+1CO2R), perfluoroalkyl ketones (CnF2n+1COR), and

Biocatalysis for the application of CO₂ as a chemical feedstock

• Apostolos Alissandratos and
• Christopher J. Easton

Beilstein J. Org. Chem. 2015, 11, 2370–2387, doi:10.3762/bjoc.11.259

• Pyrococcus furiosus does not interfere. Decarboxylases A number of enzymes are capable of catalysing the reversible interconversion of lipophilic aromatics and the more polar respective carboxylates [12]. It is thought these reactions may proceed in the carboxylation direction as a detoxification mechanism

Convenient preparation of high molecular weight poly(dimethylsiloxane) using thermally latent NHC-catalysis: a structure-activity correlation

• Stefan Naumann,
• Johannes Klein,
• Dongren Wang and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 2261–2266, doi:10.3762/bjoc.11.246

• literature procedures (see Supporting Information File 1). Compounds 7-Neo-CO2, 7-iPr-CO2 and 5Cl-Me-CO2 have not been described before and full characterization can be found in the experimental part (Supporting Information File 1). In accordance with previous findings [17][27], these NHC-carboxylates were

• thermally labile pre-catalysts both practically feasible and advantageous. Conclusion In conclusion, we have demonstrated the first polymerization of D4 using NHC-carboxylates. Sterically non-hindered, highly nucleophilic protected NHCs like 5Me-Me-CO2 offer access to an “on demand”, metal-free and

• 5Me-Me-CO2. Note that the fivefold monomer excess was used in case of BnOH being present. Thermal activation of a 5Me-Me-CO2/BnOH/D4 (1:5:500) composition after a latency period of 72 h. NHC-carboxylates part of this study (top) and polymerization scheme with initial thermal decarboxylation and final

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• -wheel” of copper(II)–carboxylate complexes [28], a structure in which the two copper(II) ions are bridged by four carboxylates in a syn–syn configuration (dCu···Cu 2.613 Å), whilst two THF molecules occupy axial coordination sites. Complex 1 displays a monomeric structure with a distorted square

• molecules being most probably bound to the copper ions in aqueous solution, while in THF, the carboxylates interact more tightly with the copper ions. This is in agreement with the 1H NMR spectra of 1, which showed well resolved peaks for the benzophenone protons in D2O, while in THF-d8 broad resonances

Synthesis of quinoline-3-carboxylates by a Rh(II)-catalyzed cyclopropanation-ring expansion reaction of indoles with halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2015, 11, 1944–1949, doi:10.3762/bjoc.11.210

• Magnus Morten Martin Hennum Tore Bonge-Hansen Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo, Norway 10.3762/bjoc.11.210 Abstract In this letter, we report a novel synthesis of ethyl quinoline-3-carboxylates from reactions between a series of indoles and

• efficient method for the synthesis of ethyl quinoline-3-carboxylates from reactions between indoles and ethyl halodiazoacetates. The reaction propably follows a cyclopropanation-ring expansion pathway. Indoles with substituents in the 3,4,5 and 6 positions were good substrates for the reaction, but a

• commercially available indoles in combination with the scope of the reaction makes the cyclopropanation-ring expansion an attractive method for an efficient synthesis of quinolone-3-carboxylates. Experimental Detailed experimental procedures and analytical data for the compounds are available in Supporting

Fe(II)/Et₃N-Relay-catalyzed domino reaction of isoxazoles with imidazolium salts in the synthesis of methyl 4-imidazolylpyrrole-2-carboxylates, its ylide and betaine derivatives

• Ekaterina E. Galenko,
• Olesya A. Tomashenko,
• Alexander F. Khlebnikov,
• Mikhail S. Novikov and
• Taras L. Panikorovskii

Beilstein J. Org. Chem. 2015, 11, 1732–1740, doi:10.3762/bjoc.11.189

• Emb. 7/9, 199034, St. Petersburg, Russia 10.3762/bjoc.11.189 Abstract A simple approach was developed for the synthesis of methyl 4-imidazolylpyrrole-2-carboxylates from easily available compounds, 5-methoxyisoxazoles and phenacylimidazolium salts under hybrid Fe(II)/Et3N relay catalysis. The

• alkyl 2H-azirine-2-carboxylates can be prepared by isomerization of 5-alkoxyisoxazoles under Fe(II)-salt catalysis [30]. Quite recently this isomerization has been used for the preparation of substituted pyrrole-2-carboxylic acid derivatives by the domino reaction of 3-aryl-5-methoxyisoxazoles with 1,3

• ammonium formate as a source of hydrogen, to give the corresponding methyl 4-(1H-imidazol-1-yl)-1H-pyrrole-2-carboxylates 12 in high yields (Scheme 3). The reaction of aq KOH with imidazolium bromides 1 at room temperature afforded the corresponding stable ylides 2 (Table 2) in high yields without

Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

• Maximilian Koy,
• Hagen J. Altmann,
• Benjamin Autenrieth,
• Wolfgang Frey and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178

• –alkylidene-triggered metathesis-based polymerizations, Ru contamination was very low (<2.5 ppm) and even outrivals earlier reported systems bearing two pyridinium carboxylates by at least a factor of 10 [14]. Clearly, both the initiator and any Ru-containing decomposition products selectively stay in the IL

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• diesters More recently, symmetric diesters have been synthetized exploiting both the activated extremities of divinyl carboxylates. C6-dicarboxylic acid diesters derivatives of the thiazoline of N-acetylglucosamine (NAG-thiazoline, 10a,b, Figure 2) were prepared and their inhibitor activities towards

• . The formed diol was mixed with an equal molar amount of divinyl sebacate and lipase as a catalyst, after some time methoxypoly(ethylene glycol) was added to react with the remaining vinyl carboxylates to give an amphiphilic polymer. This product self-assembled into nanometer-scale-sized particles in

Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

• Franziska Klitsche,
• Julian Ramcke,
• Julia Migenda,
• Andreas Hensel,
• Tobias Vossmeyer,
• Horst Weller,
• Silvia Gross and
• Wolfgang Maison

Beilstein J. Org. Chem. 2015, 11, 678–686, doi:10.3762/bjoc.11.77

• ], carboxylates [5] and phosphates [6] as well as phosphonates [7] for metal and metal oxide surfaces. In addition, bifunctional catechols like dopamine or DOPA (L-3,4-dihydroxyphenylalanine, Figure 1B), have received considerable interest as anchor groups for important metal surfaces such as titanium oxide, iron

The reactions of 2-ethoxymethylidene-3-oxo esters and their analogues with 5-aminotetrazole as a way to novel azaheterocycles

• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess and
• Viktor I. Saloutin

Beilstein J. Org. Chem. 2015, 11, 385–391, doi:10.3762/bjoc.11.44

• -oxo esters and their analogues with 5-aminotetrazole is an efficient synthetic approach to novel azaheterocycles. 2-Ethoxymethylidene-3-oxo esters bearing alkyl substituents react with 5-aminotetrazole to form ethyl 2-azido-4-alkylpyrimidine-5-carboxylates which are capable of subsequent nucleophilic

• amounts of sodium acetate in the reaction of fluorinated esters 1a,b with 5-AT in 1,4-dioxane under reflux leads to the formation of ethyl 2-amino-4-(polyfluoroalkyl)pyrimidine-5-carboxylates 4a,b (Scheme 2). In the case of 1a (R = CF3), ethyl 2-(1H-tetrazol-5-ylamino)-4-(trifluoromethyl)-pyrimidine-5

Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• azadienes onto the keto group, provides a rapid access to non-fused 2H-1,4-oxazine-5-carboxylates 4, a new type of non-spirocyclic 1,4-oxazine photochromes [15]. In the search for new compounds with useful photochromic characteristics and a high fatigue resistance we focused on 5-unsubstituted, 5-aryl-, and

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• carboxylates affords compounds 33a–c in moderate to good yields, whereas the reaction with NaN3 provided the ω,ω’-diazide 34. The latter compound served as interface for labelling with various alkyne-functionalized compounds. As proof-of-concept we successfully coupled 34 with the perylene derivative 35 to

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• metal cations (Mg2+, Al3+), which rapidly are coordinated by the carboxylate anions formed at the cathode. Finally, the corresponding metal carboxylates can be precipitated from organic solvents allowing easy product isolation. Alongside all the benefits that are associated with these sacrificial anodes

• generated carboxylates, make the use of a membrane redundant, enabling the use of a simple undivided cell [44]. Moreover, the use of membranes in non-aqueous or aprotic environments is unsatisfactory as they become poorly conducting [44]. This procedure was patented and extended to various other substrates

Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• investigated by Howdle et al. [90]. When the PFPE polymers were in their carboxylic acid form no microemulsions were formed, however, upon the conversion of the headgroups to ammonium carboxylates w/c microemulsions were observed. The length of the polymer tail was also shown to affect the ability to form

Triazol-substituted titanocenes by strain-driven 1,3-dipolar cycloadditions

• Andreas Gansäuer,
• Andreas Okkel,
• Lukas Schwach,
• Laura Wagner,
• Anja Selig and
• Aram Prokop

Beilstein J. Org. Chem. 2014, 10, 1630–1637, doi:10.3762/bjoc.10.169

• structural feature [31]. The gelation ability of the neutral ester-substituted titanocenes critically depends on the steric demand of the substituents on the cyclopentadienyl ligands. The carboxylates are valuable complexes for mediating highly chemoselective Barbier type allylations [32][33]. These findings

• started our investigation with the preparation of azide-substituted cationic titanocenes. To this end, the titanocene carboxylates 1–3 shown in Figure 1 were employed as substrates because their substitution pattern should allow a first simple assessment of structure–activity relationships. The compounds

• A–D shown in Figure 2 were used as amino-substituted azides. They are readily obtained from the corresponding diazides through a Staudinger reaction (see Supporting Information File 1 for details) [45][46]. As for the carboxylates the different tether lengths and substitution patterns of the arene

Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

• Bernd Schmidt and
• Sylvia Hauke

Beilstein J. Org. Chem. 2014, 10, 1023–1031, doi:10.3762/bjoc.10.102

• furanose 17. Facile migration of carboxylates upon TBAF-mediated desilylation of a vicinal alcohol has previously been observed by us in a different context [68]. We assume that this process starts with a nucleophilic attack of the alkoxylate 18 at the ester carbon, giving a five membered intermediate 19

Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

• Zong Guan,
• Jan C. Namyslo,
• Martin H. H. Drafz,
• Martin Nieger and
• Andreas Schmidt

Beilstein J. Org. Chem. 2014, 10, 832–840, doi:10.3762/bjoc.10.79

• indazole 3 has been generated by thermal decarboxylation of indazolium-3-carboxylates 1 [20] which belong to the class of pseudo-cross-conjugated heterocyclic mesomeric betaines (Scheme 1). Its properties have been calculated [20][21] and examined by means of vibrational spectroscopy [21]. It was shown

• aforementioned class of pseudo-cross-conjugated heterocyclic mesomeric betaines. Thus the intermediates III are related to indazolium-3-carboxylates, -amidates, and -thioamidates shown in Scheme 1 and Scheme 2. The neutralization of the charges in cross-conjugated as well as in pseudo-cross-conjugated mesomeric

Use of activated enol ethers in the synthesis of pyrazoles: reactions with hydrazine and a study of pyrazole tautomerism

• Denisa Tarabová,
• Stanislava Šoralová,
• Martin Breza,
• Marek Fronc,
• Wolfgang Holzer and
• Viktor Milata

Beilstein J. Org. Chem. 2014, 10, 752–760, doi:10.3762/bjoc.10.70

• -1H-pyrazole-4-carbonitrile (5a), alkyl 3-hydroxypyrazole-4-carboxylates 5b, 5c or 1-(3-methyl-1H-pyrazol-4-yl)ethanone (5d). The reversed addition of the enol ethers to hydrazine hydrate the formation of bis-enehydrazine 6 product was observed in two tautomeric forms: with symmetrical and

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones

• Murat Kucukdisli,
• Dorota Ferenc,
• Marcel Heinz,
• Christine Wiebe and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 466–470, doi:10.3762/bjoc.10.44

• products and 3,5-disubstituted pyrrole-2-carbonitriles 10 are obtained. Tsuge et al. reported the oxidation of pyrroline-3-carboxylates with chloranil [45] while pyrrole-2-carboxylates were obtained from the oxidation of pyrroline-2-carboxylate with chloranil [46][47] or DDQ [48]. Different oxidants were

Organobase-catalyzed three-component reactions for the synthesis of 4H-2-aminopyrans, condensed pyrans and polysubstituted benzenes

• Moustafa Sherief Moustafa,
• Saleh Mohammed Al-Mousawi,
• Maghraby Ali Selim,
• Ahmed Mohamed Mosallam and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2014, 10, 141–149, doi:10.3762/bjoc.10.11

• the products. Finally, these compounds were used for the efficient synthesis of 6-amino-5-cyanonicotinic acid ester derivatives 31a,b, ethyl 4-amino-5H-pyrano[2,3-d]pyrimidine-6-carboxylates 33a,b, 4-amino-6H-pyrrolo[3,4-g]quinazoline-9-carbonitrile 39, and 1,7-diamino-6-(N'-hydroxycarbamimidoyl)-3

• acid derivatives 31a,b, ethyl 4-amino-5H-pyrano[2,3-d]pyrimidine-6-carboxylates 33a,b, 4-amino-6H-pyrrolo[3,4-g]quinazoline-9-carbonitrile 39, and 1,7-diamino-6-(N'-hydroxycarbamimidoyl)-3-oxo-5-phenyl-3H-isoindole-4-carboxylate 40. X-ray crystal structure of 9. X-ray crystal structure of 13a. X-ray

Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C₂-symmetric building block: a strategy for the synthesis of decanolide natural products

• Bernd Schmidt and
• Oliver Kunz

Beilstein J. Org. Chem. 2013, 9, 2544–2555, doi:10.3762/bjoc.9.289

• electrocyclic ring opening to carboxylates 6 [25], although a non-concerted pathway can not be excluded (Scheme 1). To the best of our knowledge, metathesis/non-metathesis one flask sequences have not been used before for the two directional elaboration or desymmetrization of C2-symmetric building blocks. In

Gold-catalyzed regioselective oxidation of propargylic carboxylates: a reliable access to α-carboxy-α,β-unsaturated ketones/aldehydes

• Kegong Ji,
• Jonathan Nelson and
• Liming Zhang

Beilstein J. Org. Chem. 2013, 9, 1925–1930, doi:10.3762/bjoc.9.227

• Kegong Ji Jonathan Nelson Liming Zhang Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, 93106, USA 10.3762/bjoc.9.227 Abstract Gold-catalyzed intermolecular oxidation of carboxylates of primary or secondary propargylic alcohols are realized with

• regioselectivities of this oxidation with different types of internal alkynes, we examined propargylic carboxylates, which have served as a versatile platform for the development of a diverse range of gold catalysis [21]. Herein we report our findings and the development of a reliable synthesis of α-carboxy α,β

• following observations and considerations: a) propargylic carboxylates of type 4a with an internal C–C triple bond typically undergo facile 3,3-rearrangements [26][27][28][29][30] instead of 1,2-acyloxy migrations. The former process would eventually lead to the formation of the enones 6 [31]. Due to

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives via radical pathways

• Eietsu Hasegawa,
• Minami Tateyama,
• Ryosuke Nagumo,
• Eiji Tayama and
• Hajime Iwamoto

Beilstein J. Org. Chem. 2013, 9, 1397–1406, doi:10.3762/bjoc.9.156

• hexanoic acid > acetylacetone [53][54], it is possible to assign Cu(acac)2, which is ineffective in promoting the reaction, as the weakest oxidant. On the other hand, CuCl2 and Cu(OTf)2 induce reactions that follow a different pathway from those promoted by copper(II) carboxylates. These observations

• suggest that a rapid equilibrium does indeed exist between isomeric radical intermediates 9 and 10 (Scheme 7) and that the thermodynamically less stable isomer 9 undergoes fast hexenyl-radical cyclization leading to the formation of 11 in reactions promoted by copper(II) carboxylates. On the other hand, a