1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• nanoreactor because there is an acceleration of the dimerization by two orders of magnitude and the turnover of the catalyst was demonstrated. The synthesis of cyclic carbonates from epoxides and CO2 is an efficient method for CO2 fixation. The development of an effective chiral catalyst for the efficient

• binaphthyl system and the Lewis acidic metal center facilitated the enantioselective synthesis of cyclic carbonates from epoxides. Various catalyst was screened by changing the linker length (n = 4 to 8) and nucleophilic counter anion (X = I, Cl, Br), and 16c was found to be the best catalyst for the

• of the substrate scope showed that various epoxides reacted under the optimized conditions to yield optically active cyclic carbonates and epoxides [63]. 4. pH sensitive 1,2,3-triazolium macrocycles Various macrocycles show remarkable response to the pH of the environment. In the following section

Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

• Sora Park and
• Jeung Gon Kim

Beilstein J. Org. Chem. 2019, 15, 963–970, doi:10.3762/bjoc.15.93

• polymerization of cyclic carbonates, such as trimethylene carbonate (TMC) and its derivatives have been used for the controlled synthesis of high-molecular weight polymers. Among many catalysts, organocatalysts have attracted considerable attention, since the use of nontoxic catalysts warrants a safe use in

• biomedical applications [24]. The amidine base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is one of the best studied and most popular organocatalysts for ring-opening polymerizations of cyclic carbonates and lactones [25][26][27]. In contrast to the high activity of lactone polymerization, cyclic carbonate

• lactides and cyclic carbonates [27][33]. As expected, TBD effectively promoted the polymerization of trimethylene carbonate both, in solution and under solvent-free ball-milling conditions. Nearly quantitative conversions into polymer were achieved within only 5 min (Table 4). Interestingly, TBD-based ball

Systematic synthetic study of four diastereomerically distinct limonene-1,2-diols and their corresponding cyclic carbonates

• Hiroshi Morikawa,
• Jun-ichi Yamaguchi,
• Shun-ichi Sugimura,
• Masato Minamoto,
• Yuuta Gorou,
• Hisatoyo Morinaga and
• Suguru Motokucho

Beilstein J. Org. Chem. 2019, 15, 130–136, doi:10.3762/bjoc.15.13

• oxide) and conditions, the desired diastereomers were synthesised in moderate to high yields with, in most cases, high stereoselectivity. Comparison of the NMR data of the obtained diols and carbonates revealed that the four different diastereomers of each compound could be distinguished by reference to

• , syntheses of five-membered cyclic carbonates (5CCs) have been intensively investigated [5][6][7] in terms of utilisation of CO2 and the further reactions to produce functional chemicals such as oxazolizin-2-ones [8] and polyurethanes [9]. For (R)-limonene-derived 5CC (LM5CC), four diastereomers are

• that this carbonation reaction maintains the stereochemical configuration of the original diol [30][31]. Accordingly, the reactions of 2a and 2d with triphosgene successfully afforded 1a and 1d, respectively, in this study (Scheme 3). The two carbonates obtained from the diols and triphosgene were

DABCO- and DBU-promoted one-pot reaction of N-sulfonyl ketimines with Morita–Baylis–Hillman carbonates: a sequential approach to (2-hydroxyaryl)nicotinate derivatives

• Soumitra Guin,
• Raman Gupta,
• Debashis Majee and
• Sampak Samanta

Beilstein J. Org. Chem. 2018, 14, 2771–2778, doi:10.3762/bjoc.14.254

• -Michael reaction between MBH carbonates derived from an acrylate/acrylonitrile and N-sulfonyl ketimines as C,N-binucleophiles catalyzed by DABCO, followed by elimination of SO2 under the influence of base and subsequent aromatization in an open atmosphere. Keywords: MBH carbonates; metal-free; N-sulfonyl

• on the above experimental results as well as our previous report on DABCO-catalyzed reactions of cyclic sulfamidate imines with MBH carbonates of isatins [75], a plausible mechanism is presented and depicted in Scheme 2. For the first step, the nucleophilic Lewis base DABCO reacts with 2a in an SN2

• generality and scope of the reaction by reacting several aryl/heteroaryl-substituted MBH carbonates derived from acrylates 2a–j and 4-methyl-N-sulfonyl ketimines 1a–e under present sequential reaction conditions. The results are incorporated in Scheme 3. The regioselective allylic alkylation/aromatization

Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• , owing to its NH acidity with a pKa of 8.3, thus offering the opportunity for the synthesis of N-glycosides of the N-glycosylimide type [83]. However, along with the formation of N-glycosylphthalimides, a side-reaction takes place, producing both glycosyl carbonates and N-glycosyl-1,2

Direct electrochemical generation of organic carbonates by dehydrogenative coupling

• Tile Gieshoff,
• Vinh Trieu,
• Jan Heijl and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2018, 14, 1578–1582, doi:10.3762/bjoc.14.135

• Leverkusen, Germany Covestro NV, Haven 507 - Scheldelaan 420, 2040 Antwerpen, Belgium 10.3762/bjoc.14.135 Abstract Organic carbonates are an important source for polycarbonate synthesis. However, their synthesis generally requires phosgene, sophisticated catalysts, harsh reaction conditions, or other highly

• ; dehydrogenative coupling; electrochemistry; organic carbonates; Introduction Polycarbonates are high-performance polymeric materials with versatile applications in various fields with economic impact, e.g., construction, food, and pharmaceutical industry [1]. For their technical large-scale production, organic

• carbonates like diphenyl carbonate (DPC) or dimethyl carbonate (DMC) are key intermediates. Processes for the carbonate generation have been investigated since the 1950s [2]. Although the use of these starting materials is straightforward and unobjectionable at first sight, their generation usually requires

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• electrophiles such as epichlorohydrin [6], organic carbonates [7][8][9] or bis-isocyanates [10], in variable ratios depending on the required degree of reticulation. The process, of course, exploits the nucleophilic reactivity of the hydroxy groups of the macrocycle oligosaccharide unit. In general, CyNSs

Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• mild and efficient C–H alkenylation of N-pyrimidylindoles and pyrroles with alkenyl acetates using a cobalt–NHC catalyst (Scheme 1a) [17]. The same catalytic system also promoted the alkenylation using alkenyl carbamates, carbonates, and phosphates. More recently, we have achieved an N-arylimine

Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds

• Alexey Yu. Dubovtsev,
• Maksim V. Dmitriev,
• Аndrey N. Maslivets and
• Michael Rubin

Beilstein J. Org. Chem. 2017, 13, 2179–2185, doi:10.3762/bjoc.13.218

• (vinylogous carbonates and carbamates) normally requires more forcing conditions, but usually can be facilitated by addition of catalytic amounts of organic base (Scheme 2) [43]. Interestingly, we figured out that the presence of heteroatom X in the structure of enol 6 is important for the normal course of

• -catalyzed spirocyclization of enoles (vinylogous carbonates and carbamates) with 5-methoxycarbonyl-1H-pyrrolediones. Acid-catalyzed spirocyclization of enoles (vinylogous carboxylates) with 5-alkoxycarbonyl-1H-pyrrolediones. Formation of mono-imines and mono-hydrazones of 1,3-cyclohexanediones and

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

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

• developed to provide the enhanced facial selectivity for the acceptor attack [38][39][40][41]. Beyond early intramolecular glycosylations achieved via the orthoester rearrangement by Lindberg [42] and Kochetkov [43], as well as the decarboxylation of glycosyl carbonates by Ishido [44], Barresi and Hindsgaul

• glycosylation was based on the 1,2-orthoester rearrangement by Lindberg [42] and Kochetkov [43], as well as the decarboxylation of glycosyl carbonates by Ishido [44]. Intramolecular glycosylations where the glycosyl acceptor was purposefully attached directly to the leaving group of the glycosyl donor have been

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• thiacalix[4]arene variously substituted at the lower rim form 1,2-, 1,3-di- and trisubstituted macrocycles [42], depending on the nature of the alkali metal carbonates and solvent. In this paper, we describe the regioselective synthesis of p-tert-butylthiacalix[4]arene monosubstituted at the lower rim by N

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

• ) technique for the synthesis of dialkyl carbonates [90]. Using potassium carbonate, alkyl halide and 2 equiv of phase-transfer catalyst 18-crown-6 yielded dialkyl carbonate in 74%. However, in absence of 18-crown-6 the yield was only 2% at 17 h (Scheme 20). Transesterification is a synthetic approach mostly

• dialkyl carbonates [90]. Mechanochemical transesterification reaction using basic Al2O3 [91]. Mechanochemical carbamate synthesis [92]. Mechanochemical bromination reaction using NaBr and oxone [96]. Mechanochemical aryl halogenation reactions using NaX and oxone [97]. Mechanochemical halogenation

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

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

• -state LAG ball milling approach. Mack et al. looked into the formation of a dialkylurea from the parent urea in the context of the mechanochemical formation of dialkyl carbonates from metal carbonates [46]. Whereas urea is normally considered as unreactive compound, the authors succeeded to activate it

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• ], Ullmann coupling [13][14], Buchwald–Hartwig amination [15] or N-alkylation of carbazole in the presence of alkali metal carbonates under MW irradiation [16]. In our case, the N-arylation was realized under phase transfer conditions using triethylbenzylammonium chloride (TEBA) as a catalyst [17][18

Adsorption of RNA on mineral surfaces and mineral precipitates

• Elisa Biondi,
• Yoshihiro Furukawa,
• Jun Kawai and
• Steven A. Benner

Beilstein J. Org. Chem. 2017, 13, 393–404, doi:10.3762/bjoc.13.42

• aragonite. These have relevance to the prebiotic stabilization of RNA, where such carbonate minerals are expected to have been abundant, as they appear to be today on Mars. Keywords: carbonates; natural minerals; origins of life; RNA adsorption; synthetic minerals; Introduction It has been nearly 70 years

• partition of radiolabel RNA between the two is measured. This strategy then asks whether the trend in radiolabeled RNA adsorption is consistent across their various forms and presentations, especially within a set of minerals having a common anion (for example, all carbonates) but differing in their

• . Further, we speculate that these trends can be accounted for by the changing size of the mineral lattice resulting from different ionic radii of different elements in a Periodic Table series. Results Carbonates We examined first various binary carbonate minerals with Group II (alkaline earth) cations

First DMAP-mediated direct conversion of Morita–Baylis–Hillman alcohols into γ-ketoallylphosphonates: Synthesis of γ-aminoallylphosphonates

• Marwa Ayadi,
• Haitham Elleuch,
• Emmanuel Vrancken and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2906–2915, doi:10.3762/bjoc.12.290

• , without any additive, provided, after thermal Arbuzov rearrangement, a variety of diethyl allylphosphonates (Scheme 1, reaction 3) [18]. Moreover, the asymmetric allylic substitution of MBH carbonates with diphenyl phosphonate using chiral thiourea phosphite as catalyst, afforded the related

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• Tsuji–Trost reaction involving, as substrates, allyl carboxylates [2], carbonates [3], and phosphates [4]. Obviously, the direct nucleophilic allylic substitution of allyl alcohols is a more attractive process especially from an economical and environmental point of view [5], as water, generated by this

Isosorbide and dimethyl carbonate: a green match

• Fabio Aricò and
• Pietro Tundo

Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218

• presence of the nitrogen bicyclic base DBU. It has been, in fact, reported that organic carbonates are activated by DBU via formation of an N-alkoxycarbonyl DBU derivative [67][68][69][70][71]. However, in this case study, DBU most probably promotes the formation of the methoxycarbonyl reaction

• temperature in the presence of potassium carbonate (Table 3) [84]. Under these conditions, due to the presence of four chiral centres in the isosorbide backbone, three products can be formed, the wanted dicarboxymethyl carbonate (DCI) and two monocarboxymethyl carbonates MCI-1 and MCI-2 (Scheme 3). When

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• with a large substrate scope. Keywords: carbonates; DBN; DBU; lactams; p-nitrophenyl; Introduction Among various organic bases, amidines such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) having an imino group attached to the α-carbon of the amine are

• behavior of DBU towards imidazolides providing ε-caprolactam-derived carbamates and amides [17]. Here, in this report we present the results obtained by the reaction of DBU and DBN with highly electrophilic p-nitrophenyl carbonates leading to ε-caprolactam and γ-lactam carbamates. p-Nitrophenyl carbonates

• are highly reactive compounds that are usually treated with alcohols or amines to give either a new carbonate or a carbamate-linked compound depending on the nucleophile. In one of our earlier reports, polycarbamate nucleic acids were synthesized from p-nitrophenyl carbonates with amines of nucleic

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

• reactions, specifically for the conversion of nontoxic compounds such as dialkyl carbonates to both linear mono-transesterification products or alkylene carbonates. An introductory survey compares pros and cons of classic catalysts based on both acidic and basic systems, to ionic liquids. Then, innovative

• /nucleophilic) activation of reactants. Keywords: ionic liquids; transesterification; organocatalysts; organic carbonates; Review Introduction Transesterification catalysts The transesterification is one of the classical organic reactions that has found numerous applications in laboratory practice as well as

• popular catalytic systems [3]. These include both acids such as sulfuric, sulfonic, phosphoric, and hydrochloric, and bases such as metal alkoxides, acetates, oxides, and carbonates. It is worth mentioning, that transesterification reactions are frequently carried out over solid (heterogeneous) catalysts

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• yield a 4,5-dihydro-1H-ketopyrrole 121 (Scheme 36) [289]. 1.2 Criegee rearrangement The Criegee rearrangement involves the transformation of a peroxide, mainly peroxyesters B, into carbonates, esters, or ketones C and alcohols D through an oxygen insertion or consecutive oxygen insertions. The

• of triarylmethanols 159a–d [299]. The successive insertion of oxygen atoms gave rise to diaryl carbonates 160a–d in good yields (Scheme 47). In the last years, new enantiospecific approaches for the synthesis of sesquiterpenes 162 from ketone 161 were developed [301][302][303][304][305][306][307]. In

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• carbonates (Scheme 19) to afford compounds 90–99in general with good yields, diastereomeric ratios and enantioselectivities. Aliphatic carbonates are also good substrates for this reaction but the corresponding adducts are obtained in lower diastereoselectivity. This work demonstrates that the selectivity of

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• by photolysis of 1a, the reaction was performed in different solvents in the absence or presence of a base. As solvents, alcohols and aqueous organic solvent mixtures were tested and alkali metal hydroxides, carbonates or acetates were screened as the base. All reactions were carried out by

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• ; elimination of the catalyst then generates the exo-methylene adduct. For example, Lu and co-workers have used β-ICPD to react isatin-derived MBH carbonates 18 with nitroalkanes 19 [29]. The resulting adducts 20 could be converted to the corresponding spiroxindole 21 via a Zn/HOAc mediated reduction of the

• nitro functionality (Scheme 5). Similarly, Kesavan and co-workers reacted 3-O-Boc-oxindoles 23 with MBH carbonates 22 to generate a range of spirocyclic scaffolds containing α-exo-methylene-γ-butyrolactone 24 – again using β-ICPD (Scheme 6) [30]. Nazarov cyclization An asymmetric Nazarov cyclization has

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• catalysts induced the formation of cyclic carbonates under mild reaction conditions (25–35 °C; 1–10 bar carbon dioxide pressure). However, with cyclohexene oxide under the same reaction conditions, the same catalysts induced the formation of polycarbonate. The catalysts could be recovered from the reaction

• achieving this goal is to produce cyclic carbonates or polycarbonates from carbon dioxide and the corresponding epoxides (Scheme 1). Cyclic carbonates are an important class of solvents [2] and starting materials in organic synthesis [3][4][5][6]. Although a significant array of catalysts have been

• developed for the production of cyclic carbonates [7][8][9] and polycarbonates [10][11] from carbon dioxide and epoxides, the most developed and privileged set of catalysts are based on Lewis acidic metal–salen complexes. In particular, cobalt(III) and chromium(III) complexes were found to be highly