Quinone-catalyzed oxidative deformylation: synthesis of imines from amino alcohols

• Xinyun Liu,
• Johnny H. Phan,
• Benjamin J. Haugeberg,
• Shrikant S. Londhe and
• Michael D. Clift

Beilstein J. Org. Chem. 2017, 13, 2895–2901, doi:10.3762/bjoc.13.282

• deformylation of 2-phenylglycinol (1a) to deliver N-PMP imine 7a (Table 1). We selected quinone catalysts (2a−c) that have previously been utilized in amine oxidation reactions [21][32][40][41], and began with reaction conditions similar to those developed for our quinone-catalyzed oxidative decarboxylation

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• excess amounts to suppress competing ‘simple’ decarboxylation (-CO2− ↔ -H exchange) reactions to the corresponding toluene derivatives [25]. Following the established protocol and utilizing a 1:1 acetone/water mixture as reaction medium [27][30], irradiations with UVB light (300 ± 30 nm) for 4 hours

• one of the N-ethyl groups of the side chain. The mechanism of the photodecarboxylation is well established (Scheme 7) and involves triplet sensitization by acetone and electron transfer between the phenylacetate and the excited phthalimide [55][56][57]. Subsequent decarboxylation, radical combination

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• CF3SO2Na (Scheme 56) [81]. The authors used basically the same protocol as Sanford and Molander but observed that a more diluted reaction medium gave improved reaction yields. Trifluoromethylation of alkenes by decarboxylation: Liu and co-workers were the first to describe the copper-catalysed

A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• affording 2a after protonation and thus regenerating the catalyst intermediate 3. 1H NMR analysis using CD3CN showed high levels of HCCl3, which could be form after decarboxylation of the basic species. In an attempt to obtain a better understanding at this dimerization reaction and to give new insights

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• (thermodynamically controlled) Mannich-type adduct B, followed by rapid irreversible decarboxylation of B into compound 4a. Contrastingly, in a high-polar solvent, the intermediate A is so labile that it undergoes decarboxylation to product 5a rather than rearrangement to B. The proposed reaction mechanism is

• supported by the known effect of solvent polarity on the decarboxylation rate of malonic acid derivatives which was claimed to be faster in polar media [40]. To study the substrate scope of the regioselective additions of malonic acid, we introduced substituted pyrimidones 2b–m in the reaction and performed

• the Michael-type adduct, phenyl 2-(3-methyl-2-oxo-6-trifluoromethyl-1,2,3,4-tetrahydropyrimidin-4-yl)acetate (6a). The presence of DBU caused substantial decarboxylation of starting reagent 1a (Table 3, entry 3). This unwanted process necessitated using of up to 6 equivalents of 1a to reach a

Comparative profiling of well-defined copper reagents and precursors for the trifluoromethylation of aryl iodides

• Peter T. Kaplan,
• Jessica A. Lloyd,
• Mason T. Chin and
• David A. Vicic

Beilstein J. Org. Chem. 2017, 13, 2297–2303, doi:10.3762/bjoc.13.225

• trifluoromethylation ‘catalysis’ using copper have been observed [4][5][6][7][8][9], but these reactions typically only work for aryl iodides and have a low substrate scope, low turn-over values, and/or involve decarboxylation reactions at high temperatures. Stoichiometric trifluoromethylating agents are therefore

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

Iodoarene-catalyzed cyclizations of N-propargylamides and β-amidoketones: synthesis of 2-oxazolines

• Somaia Kamouka and
• Wesley J. Moran

Beilstein J. Org. Chem. 2017, 13, 1823–1827, doi:10.3762/bjoc.13.177

• 2-oxazoline formation through the iodoarene-catalyzed cyclization of β-amidoketones 5. These are readily prepared by alkylation of the corresponding β-ketoester followed by decarboxylation (Scheme 4) [40][41]. The cyclization of β-amidoketones 5 was successful with the same conditions as

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• tryptophan derivatives with appropriate aldehydes. A hypervalent iodine reagent, iodobenzene diacetate was used in stoichiometric quantities to facilitate both oxidative decarboxylation/dehydrogenation of 108–110 to afford the desired natural products 111–113 (Scheme 42). Conclusion Substantial amount of

Synthesis and metal binding properties of N-alkylcarboxyspiropyrans

• Alexis Perry and
• Christina J. Kousseff

Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154

• yields from 60–82% (Table 1, entries 3, 7, and 9–11). This protocol was ineffective for the synthesis of C2SP (n = 1) and C4SP (n = 3). In the former case, the intermediate N-ethanoate indolium salt 3a underwent thermal decarboxylation to give N-methylindolium salt 7, in a similar manner to that

• previously reported [28]. Presumably, this reaction proceeds via azomethine ylid 6 (Scheme 3); analogous indolium ylids have been used synthetically in 1,3-dipolar cycloadditions [29] and mechanistic studies have been published on the related decarboxylation of pyridinium 2-carboxylates [30]. Fortunately, α

• , it is ineffective with bromoacetic acid and bromobutyric acid, where decarboxylation and intramolecular lactonisation respectively compete with N-alkylation. In these cases, we have developed alternative, though lower-yielding procedures. N-Alkylcarboxyspiropyrans can function as colourimetric

Sustainable synthesis of 3-substituted phthalides via a catalytic one-pot cascade strategy from 2-formylbenzoic acid with β-keto acids in glycerol

• Lina Jia and
• Fuzhong Han

Beilstein J. Org. Chem. 2017, 13, 1425–1429, doi:10.3762/bjoc.13.139

• phthalides in good to excellent yields. Conclusion: A concise and efficient synthesis strategy of 3-substituted phthalides from 2-formylbenzoic acid and β-keto acids via a catalytic one-pot cascade reaction in glycerol has been accomplished. Keywords: β-keto acid; decarboxylation; glycerol; one-pot cascade

• -formylbenzoic acid (1a) is attacked preferably by benzoylacetic acid (2a) in the presence of a base to afford the aldol intermediate A. Next, the subsequent facile decarboxylation and lactonization of intermediate A leads to 3-phenacylphthalide (3a). Conclusion In summary, we have accomplished a sustainable and

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• formation of HPA dimer 11 and product of its decarboxylation 12 (Scheme 1). The formation of these two products (observed by 1H NMR) was recently reported by Knapp et al. [35] as a result from the treatment of HPA with a strong base (which was absent in our case). The failure to activate sterically hindered

• fate of Mannich adduct 13e. Mechanistic rationale for the 13e→ syn/anti-10e conversion. Decarboxylation of anti/syn-10h. Indolo[1,2-b]isoquinolonic acids 10 obtained via the CCR of indolenines 9. Supporting Information Supporting Information File 338: Detailed experimental procedures, analytical data

Total syntheses of the archazolids: an emerging class of novel anticancer drugs

• Stephan Scheeff and
• Dirk Menche

Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108

• stereoselective elimination and decarboxylation in situ. The corresponding aldehyde 22 was then homologated by an Abiko–Masamune anti-aldol addition [74] with ephedrine-derived ester 23, which proceeded with excellent yield and stereoselectivity. However, the subsequent removal of the sterically hindered chiral

New tricks of well-known aminoazoles in isocyanide-based multicomponent reactions and antibacterial activity of the compounds synthesized

• Maryna V. Murlykina,
• Maryna N. Kornet,
• Sergey M. Desenko,
• Svetlana V. Shishkina,
• Oleg V. Shishkin,
• Aleksander A. Brazhko,
• Vladimir I. Musatov,
• Erik V. Van der Eycken and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2017, 13, 1050–1063, doi:10.3762/bjoc.13.104

• basic. DMF increases solubility of imines 5, while the application of strong acid (HClO4) promotes Shiff bases protonation. Phenylpyruvic acid (1') was also applied as carbonyl component in GBB-3CR to obtain imidazopyrazoles having a carboxylic group. However, the process of decarboxylation took place

Synthesis and enzymatic ketonization of the 5-(halo)-2-hydroxymuconates and 5-(halo)-2-hydroxy-2,4-pentadienoates

• Tyler M. M. Stack,
• William H. Johnson Jr. and
• Christian P. Whitman

Beilstein J. Org. Chem. 2017, 13, 1022–1031, doi:10.3762/bjoc.13.101

• 4-oxalocrotonate tautomerase (4-OT) [8]. Decarboxylation of 4a by the metal-dependent 4-oxalocrotonate decarboxylase (4-OD) generates 2-hydroxy-2,4-pentadienoate (5a) [9][10][11]. 4-OD functions in a complex with the next enzyme in the pathway, a metal-dependent vinylpyruvate hydratase (VPH) [7

• -chloro derivative). The enzymatic synthesis relies on the actions of the 4-OT and 4-OD/E106QVPH (both from P. putida mt-2), which carry out ketonization and decarboxylation, respectively, of 3c and 3d [11]. (The 4-OD/E106QVPH retains full decarboxylase activity, but has very little hydratase activity [10

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• this case, activation of the Csp–COOH occurs via decarboxylation followed by the coupling with an iminium electrophile to produce the propargylamine. Although the strategy is interesting, functionalized acetylene carboxylic acids are difficultly accessible and the reaction is less 'atom economic

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• decarboxylation (Flow III and Flow IV) led to the target (S)-rolipram in 50% overall yield. The systems was designed in order to keep the level of the palladium in solution as low as possible (<0.01 ppm). Another outstanding proof of concept, which demonstrates the potential of flow chemistry for sustainable

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