Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• rhodium(II) complex 220 followed by the carboxylic methyl ester hydrolysis/decarboxylation in DMSO/H2O at 120 °C with up to 72% enantiomeric excess (Scheme 60) [89]. 1.7 From epoxides and cyclopropanes The chalcone epoxides 221 ring opening catalyzed by indium(III) chloride, followed by a intramolecular

Decarboxylative and dehydrative coupling of dienoic acids and pentadienyl alcohols to form 1,3,6,8-tetraenes

• Ghina’a I. Abu Deiab,
• Mohammed H. Al-Huniti,
• I. F. Dempsey Hyatt,
• Emma E. Nagy,
• Kristen E. Gettys,
• Sommayah S. Sayed,
• Christine M. Joliat,
• Paige E. Daniel,
• Rupa M. Vummalaneni,
• Andrew T. Morehead Jr,
• Andrew L. Sargent and
• Mitchell P. Croatt

Beilstein J. Org. Chem. 2017, 13, 384–392, doi:10.3762/bjoc.13.41

• this reaction, substitutions at every unique position of both coupling partners was examined and two potential mechanisms are presented. Keywords: decarboxylation; diene; dienoate; palladium; pentadienyl; tetraene; Introduction The construction of sp2–sp3 carbon–carbon bonds remains a difficult and

• , entries 2–8). The use of equimolar amounts of methanol and water as a proton source allowed for decarboxylation to take place but with a low yield (Table 1, entry 9) and the reaction run in TFE as a solvent did not result in any decarboxylation (Table 1, entry 10). In addition to the requirement for water

• yield for decarboxylation with sorbate 13, the initial attempt used inexpensive sorbic acid as the dienoic acid. Gratifyingly, this reaction was successful and it was again determined that no isomerization to the fully conjugated system was observed (Table 2, entry 1). Other bis-allylic leaving groups

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• biosynthetic cycle is KS-catalyzed chain extension. This reaction occurs by nucleophilic attack of an enolate generated by decarboxylation of an ACP-bound extender unit onto the starter unit or chain extension intermediate attached to the active site cysteine of the KS domain. The face of the enolate which is

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• cyanoacetates (α-cyanoesters). These compounds are particularly versatile reagents in organic synthesis including multicomponent reactions [109][110][111][112][113]. However, like decarboxylation for related malonic ester or acetoacetates, an easy access to the removal of the cyano group should encourage future

• reductive decyanation Among the other procedures mentioned in our previous review [9], the base [129][130] or acid-induced [131][132][133][134] hydrolysis–decarboxylation sequence appears as a classical pathway (Scheme 28). In the particular case of diphenylacetonitriles, an addition–elimination mechanism

Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

• Matthias C. Letzel,
• Hans J. Schäfer and
• Roland Fröhlich

Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5

• anodic decarboxylation of five malonic acid derivatives. These were prepared from benzyl malonates and four menthol auxiliaries. Coelectrolyses with 3,3-dimethylbutanoic acid in methanol at platinum electrodes in an undivided cell afforded hetero-coupling products in 22–69% yield with a

• . Keywords: anodic decarboxylation; diastereoselectivity; Kolbe electrolysis; radical hetero-coupling; radical homo-coupling; Introduction Intermolecular radical additions with high diastereoselectivity have been described for a number of cases [1][2][3][4][5][6][7][8][9]. There are much fewer reports on

• ], and in intermolecular coupling of radicals generated by anodic decarboxylation of carboxylic acids [15][16]. At the anode radicals can be generated by anodic decarboxylation of carboxylic acids in molar quantities, in a simple procedure, unaffected by cage effects and in large diversity. For that

A new paradigm for designing ring construction strategies for green organic synthesis: implications for the discovery of multicomponent reactions to build molecules containing a single ring

• John Andraos

Beilstein J. Org. Chem. 2016, 12, 2420–2442, doi:10.3762/bjoc.12.236

• ], or malonate diesters via Claisen condensations followed by hydrolysis and decarboxylation. The greenest routes appear in the [4 + 2] strategy. The three-step route beginning with photochemical ring opening of cyclobutenone to give vinylketene, followed by Diels–Alder addition to ethylene leading to

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

• that the decarboxylation of glycerol carbonate increased with increasing catalyst concentration in solution and thus, the high basicity of the catalyst was not the sole reason for the high activity. This implied that both, the presence of a basic (anionic) center and an electrophilic (cationic) center

• (conversion >99% and yield >90%) with respect to conventional organic and inorganic bases. In addition, the reactions proceed without decarboxylation even at high temperatures (T > 150 °C), as opposed to the outcome using both solid bases and zeolites, that generate large amounts of CO2. The

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• . The corresponding pyrrolidinylphosphonates 300 were isolated in 43–86% yields under refluxing in toluene (Scheme 61) [99]. The reaction was proposed to proceed through the condensation of proline with an aldehyde under formation of oxazolidin-5-ones 298 followed by decarboxylation to give the

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• oxidatively decarboxylated cysteine residue onto a Dha residue derived from serine (Figure 5A). Extensive in vitro experiments indicate that decarboxylation of cysteine precedes 1,4-addition and is catalysed by a flavoprotein (EpiD) in epidermin biosynthesis [66][67], which uses flavin mononucleotide (FMN) to

• oxidise the cysteine. A mechanistic proposal based on structural data involves the oxidation of the thiol to a thioaldehyde, which then functions as an electron sink to facilitate decarboxylation to generate the double bond between Cα and Cβ [66] (Figure 5A). The functional characterisation of EpiD led to

• the identification of homologous bacterial flavoproteins (Dfp) that catalyse the decarboxylation of 4’-phospho-N-pantothenoylcysteine to 4’-phosphopantetheine, which is essential for coenzyme A biosynthesis [68] (Figure 5B). This demonstrates how the mechanistic analysis of secondary metabolism can

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• enantioselectivities (up to 99% ee, Scheme 10) [26]. The reaction involved a decarboxylation and an Yb(OTf)3/PyBox (L6)-catalyzed aldol addition. 4 Å Molecular sieves were found to be able to enhance the stereoselectivity. Steric hindrance between substituents and the metal/ligand complex slightly decreased the ee

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• carboxylate complexes in their homochiral form (Table 1) [39]. Modest enantiomeric excesses were provided by the three tested catalysts. The reactions carried out with complex 17a and 17b show very similar stereoselectivity, forming the R-enantiomer of compound 16 as the main product after decarboxylation

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

• M. Fernanda N. N. Carvalho,
• M. João Ferreira,
• Ana S. O. Knittel,
• Maria da Conceição Oliveira,
• João Costa Pessoa,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

• Supporting Information File 3. From these calculations we can draw the following conclusions: i) imines formed by reaction of amino acids with carbonyl compounds have the tendency to lose CO2 upon deprotonation of the carboxyl group. Without a negative charge at the carboxyl group, decarboxylation is

• difficult; ii) whether the deprotonation is followed by a decarboxylation or not, depends on the ability of the remaining molecule to accommodate the negative charge; iii) the best way to achieve this accommodation is by “delocalization” over one or more double bonds. Because of this, imines of 1,2

• -dicarbonyl compounds (like glyoxal and ninhydrin) are particularly well-suited for decarboxylation. When such an imine can establish a zwitterionic structure with a deprotonated carboxyl and a protonated carbonyl oxygen or imine nitrogen, decarboxylation is fast and efficient. When trying to optimize the

Antibiotics from predatory bacteria

• Juliane Korp,
• María S. Vela Gurovic and
• Markus Nett

Beilstein J. Org. Chem. 2016, 12, 594–607, doi:10.3762/bjoc.12.58

• , which is responsible for the production of auriculamide. According to the current biosynthetic model, the scaffold of auriculamide is assembled on an NRPS/PKS enzyme complex. A decarboxylation reaction was proposed to shorten the off-loaded carboxylic acid and to give rise to the unusual end group of

Synthesis and reactivity of aliphatic sulfur pentafluorides from substituted (pentafluorosulfanyl)benzenes

• Norbert Vida,
• Jiří Václavík and
• Petr Beier

Beilstein J. Org. Chem. 2016, 12, 110–116, doi:10.3762/bjoc.12.12

• -benzoquinone with cyclopentadiene afforded the Diels–Alder adducts. Decomposition of 3-(pentafluorosulfanyl)muconolactone in acidic, neutral and basic aqueous media was investigated and the decarboxylation of 2-(pentafluorosulfanyl)maleic acid provided 3-(pentafluorosulfanyl)acrylic acid. Keywords

• : dearomatization; decarboxylation; Diels–Alder reaction; oxidation; pentafluorosulfanyl group; Introduction Fluorinated organic compounds have been one of the foci of chemical industry for the last several decades. The unique properties of fluorine atoms and fluorinated groups have been exploited in various

• aqueous sodium carbonate. However, it underwent decarboxylation in DMSO-d6. Monitoring by NMR showed decarboxylation even at room temperature. After 90 h at ambient temperature the starting compound 4 disappeared and 3-(pentafluorosulfanyl)prop-2-enoic acid (23) was formed. At 65 °C the starting material

A convergent, umpoled synthesis of 2-(1-amidoalkyl)pyridines

• Tarn C. Johnson and
• Stephen P. Marsden

Beilstein J. Org. Chem. 2016, 12, 1–4, doi:10.3762/bjoc.12.1

• the reaction of alanine-derived azlactone 6 with 4-methylpyridine N-oxide (7) we found that when water (in the form of 1 M HCl) was employed as a nucleophile, the product isolated was in fact the 2-(1-benzamidoethyl)-4-methylpyridine (8a), formed by facile decarboxylation of the intermediate

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

• reactions at high temperature (150–200 °C) or under basic conditions to generate fluoroalkyl anion sources for the formation of fluoroalkylcopper species. The fluoroalkylation reactions, which proceed through decarboxylation or tetrahedral intermediates, are useful protocols for the synthesis of

• fluoroalkylated aromatics. Keywords: β-carbon elimination; carbon–carbon bond cleavage; decarboxylation; tetrahedral intermediate; trifluoroacetate; fluoral; trifluoromethylation; Introduction Organofluorine compounds attract attention because of their applicability in various fields, such as medicine

• hemiaminals derived from fluoral (CF3C(OSiMe3)NR2), can generate CnF2n+1Cu via carbon–carbon bond cleavage. Herein we focus on Cu-mediated perfluoroalkylation reactions through which carbon dioxide, the esters, or the N-formylamines are eliminated from the perfluoroalkyl reagents. Review Decarboxylation of

Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

• Antonia Di Mola,
• Maximilian Tiffner,
• Francesco Scorzelli,
• Laura Palombi,
• Rosanna Filosa,
• Paolo De Caprariis,
• Mario Waser and
• Antonio Massa

Beilstein J. Org. Chem. 2015, 11, 2591–2599, doi:10.3762/bjoc.11.279

• to obtain both the enantiomers of chiral bioactive compounds. In this case, we focused on (R,R)-8a, which afforded the required (S)-7 (the absolute configuration has been previously determined by vibrational circular dichroism) [31]. Asymmetric synthesis of 9 by decarboxylation of (S)-7 Although

• poor enantioselectivity (ee <10%) [9], while racemic analogues of 9 were resolved in the past in very low yields [4]. This disappointing picture prompted us to find a viable access route to enantioenriched 9. We thus investigated the decarboxylation of the chiral dimethyl 2-(S)-(1-oxoisoindolin-3-yl

• )malonate ((S)-7), according to Scheme 2. We firstly focused on two well-known mild procedures in order to avoid the classical harsh acidic conditions. Disappointingly, modifications of the Krapcho decarboxylation performed with a LiCl/H2O/DMF mixture under reflux [36][37] led to partial racemization of the

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• of ethyl (phenylsulfonyl)acetate, a methylsulfonyl anion equivalent, to cyclobutene ester 49 followed by a sequence consisting of saponification, regioselective decarboxylation and reesterification to afford methyl ester 50. The ester group was reduced with lithium aluminum hydride and the resulting

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• incorporation pattern in the tricyclic aromatic moiety suggests a normal PKS assembly line. Moreover, a decarboxylation step is indicated by incorporation of the acetate methyl carbon atom into C-18. In contrast, the origins of C-13 to C-17 remained unclear because of low incorporation of acetate into this part

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

• decarboxylation. In some autotrophs this pathway is known to operate in the reverse (reductive) direction resulting in CO2 fixation through carboxylation [52]. Autotrophic fixation through the reductive TCA cycle was first described by Arnon and Buchanan [53], and hence is also referred to as the Arnon–Buchanan

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

• 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

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• compounds. At the same time, the related molecular system of 1,3-tropolone has been insufficiently investigated. Therefore, the development of methods for the synthesis of 1,3-tropolones and the study of their properties is of considerable interest. The parent compound was first obtained via decarboxylation

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• -component annulation intermediate 60 which led to the formation of indolizine 61 via oxidative decarboxylation. And the bromination of 61 took place in situ to give products 59 via an unprecedented dehydrogenative bromination (Scheme 19). By making use of the copper-mediated arene C–H bond halogenation

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• both solution [38][54][55], and solid state studies [62]. This decarboxylation is favorable for precursors that generate stabilized RXCH2• radicals, thus explaining the superior yields and conversions recorded. Radical stabilization from the simple aliphatic acids of Scheme 5 (top) is minimal; so back

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• , 1,3-cyclododecadiene (337) was reacted with maleic anhydride to give the DA product 338 (21%). Later, the DA adduct 338 was heated under reflux in 10% aq tetrahydrofuran to afford the diacid, which on decarboxylation in the presence of lead tetraacetate in a toluene/pyridine mixture delivered compound