Organofluorine chemistry: Difluoromethylene motifs spaced 1,3 to each other imparts facial polarity to a cyclohexane ring

• Mathew J. Jones,
• Ricardo Callejo,
• Alexandra M. Z. Slawin,
• Michael Bühl and
• David O'Hagan

Beilstein J. Org. Chem. 2016, 12, 2823–2827, doi:10.3762/bjoc.12.281

• conformation. To the best of our knowledge, 2,2,6,6-tetrafluorocyclohexanol is the only derivative containing this feature reported so far. It was prepared in an eight step synthesis [22]. At the outset we explored a more direct synthesis of this arrangement based on deoxofluorination of 1,3-diketones 5 with

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

• traditional way this heterocycle is synthesized from urea, aldehydes, and 1,3-diketones. The method described in this work is quite general and can be applied to any monocyclic structure. The Supporting Information contains an atlas of target bond dissection maps applied to 27 kinds of heterocyclic structures

• 1,3-diketones, urea, and aldehydes. A full integer partitioning and target bond dissection mapping analysis for three-component couplings of this heterocycle, as shown in Figure 9, indicates that the chemical space consists of twelve [3 + 2 + 1], six [4 + 1 + 1], and two [2 + 2 + 2] possible

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

• of the MBH carboxylates with aliphatic 1,3-diketones in the presence of K2CO3. A drawback of these synthetic approaches is the need to first perform the acylation step of the corresponding allyl MBH alcohols. For this reason, we herein report an efficient direct method for the allylation of β

Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations

• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1170–1177, doi:10.3762/bjoc.12.112

• Paul Hommes Hans-Ulrich Reissig Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, D-14195 Berlin, Germany 10.3762/bjoc.12.112 Abstract The scope of a flexible route to unsymmetrically functionalized bipyridines is described. Starting from 1,3-diketones 1a–e, the

• we reported on a new pyridine synthesis starting from symmetrically substituted 1,3-diketones 1a and 1b, respectively, that were converted into the corresponding β-ketoenamines and subsequently by N-acylation into β-ketoenamides such as 3a or 3b [1]. Their cyclocondensation followed by O-alkylation

• available in excellent yields from the 1,3-diketones 1a and 1b employing aqueous ammonia in the presence of silica gel [21]. Compound 2c was prepared from 1c in 87% yield with ammonium formate [22][23]. Interestingly, treatment of 1c with aqueous ammonia/silica gel failed to give 2c, deacetylation to 1

Investigation on the reactivity of α-azidochalcones with carboxylic acids: Formation of α-amido-1,3-diketones and highly substituted 2-(trifluoromethyl)oxazoles

• Kandasamy Rajaguru,
• Arumugam Mariappan,
• Rajendran Suresh,
• Periasamy Manivannan and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2015, 11, 2021–2028, doi:10.3762/bjoc.11.219

• Abstract The reaction of α-azidochalcones with carboxylic acids has been investigated resulting in the formation of α-amido-1,3-diketones under microwave irradiation via in situ formation of 2H-azirine intermediates. An interesting reaction is described wherein, with trifluoroacetic acid at lower

• temperature, it affords highly substituted 2-(trifluoromethyl)oxazoles. These flexible transformations proceed under solvent free conditions in good to excellent yields without any catalyst. Keywords: α-amido-1,3-diketones; α-azidochalcones; carboxylic acids; 2H-azirines; oxazoles; Introduction α

• various substituted benzoic acids 2d–g as well and the resultant α-amido-1,3-diketones 3k–o are obtained in moderate to good yields (Figure 3). The mechanism for the formation of α-amido-1,3-diketone 3 is given in Scheme 2. Initially, by thermolysis, α-azidochalcone undergoes denitrogenative decomposition

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

• 5-acyl-substituted 2H-1,4-oxazines. They could, in principle, be prepared from azirines and α-diazo ketones or 2-diazo-1,3-diketones via ring opening across the N–C2 bond in the intermediate azirinium ylides to form 2-azabuta-1,3-dienes and subsequent cyclization of the latter into 2H-1,4-oxazines

• the mechanism of trapping of dihydroazireno[2,1-b]oxazole intermediates by acetyl(methyl)ketene were investigated by the DFT method. Results and Discussion Rhodium(II) carbenoids generated from α-diazoketones or 2-diazo-1,3-diketones react with various nitrogen-containing compounds, such as amines [16

• generated by thermolysis of 2-diazo-1,3-diketones [12] or 5-arylfuran-2,3-diones [13]. Therefore, the presence of compounds 8f,g among the reaction products provides evidence for the formation of some amounts of acetyl(methyl)ketene (12) under the reaction conditions, which, in turn, gives us insight to the

The unexpected influence of aryl substituents in N-aryl-3-oxobutanamides on the behavior of their multicomponent reactions with 5-amino-3-methylisoxazole and salicylaldehyde

• Volodymyr V. Tkachenko,
• Elena A. Muravyova,
• Sergey M. Desenko,
• Oleg V. Shishkin,
• Svetlana V. Shishkina,
• Dmytro O. Sysoiev,
• Thomas J. J. Müller and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2014, 10, 3019–3030, doi:10.3762/bjoc.10.320

• of the compounds 4–6a through the intermediate 7 (pathway A) as for cyclic 1,3-diketones [13][25] was excluded because the latter does not react with amide 3a under any comparable conditions. Most likely the formation of chroman-3-carboxamide 4a proceeds through imine 8 (pathway B) since the reaction

(CF₃CO)₂O/CF₃SO₃H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

• JungKeun Kim,
• Elvira Shokova,
• Victor Tafeenko and
• Vladimir Kovalev

Beilstein J. Org. Chem. 2014, 10, 2270–2278, doi:10.3762/bjoc.10.236

• application of the proposed protocol allowed for the synthesis of selected polysubstituted pyrazoles in a one-pot procedure directly from acids and ketones. Keywords: Claisen condensation; 1,3-diketones; heterocycles; triflic acid; trifluoroacetic acid anhydride; Introduction 1,3-Diketones represent one of

• synthesis of β-diketones from acids and ketones with an immediate activation of both carbonyl and methylene components in the course of the reaction. Herein, we would like to describe a direct and operationally simple TFAA/TfOH-mediated synthesis of 1,3-diketones from unmodified carboxylic acids and ketones

• simple and effective synthetic approach to 1,3-diketones based on the TFAA/TfOH-mediated acylation of ketones with carboxylic acids. Advantages of this approach are the ready availability of the starting materials, the simple operational procedure, and the possibility to realize the one-pot immediate

Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates

• Jan Szabo,
• Kerstin Karger,
• Nicolas Bucher and
• Gerhard Maas

Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234

• 1,3-diketones follow condensation/cyclization pathways resulting in unsymmetrical N-heterocyclic products [14][15]. Azidation of TAG-Cl with two equivalents of sodium nitrite in water afforded the highly shock- and friction-sensitive (5-azido-1H-tetrazol-1-yl)carbonimidoyl diazide rather than the

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• excellent ee (up to 96%). In subsequent transformations, the β-lactone products underwent various ring opening reactions to provide very useful derivatives, such as 1,3-diketones and enol esters, with good diastereoselectivity. 2.12 Annulations through domino aza-MBH/Michael reactions Because

A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H)-furanones

• Jubi John,
• Eliza Târcoveanu,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 1462–1470, doi:10.3762/bjoc.10.150

• [19][20][21][22][23][24][25][26]. Synthetic routes for the preparation of these compounds involve transformations of substituted α-hydroxy-1,3-diketones [15][17], substituted furans [27][28][29], cyclization of allenic hydroxyketones [30], transition metal-catalyzed strategies (Au [31][32][33], Pt [34

Secondary amine-initiated three-component synthesis of 3,4-dihydropyrimidinones and thiones involving alkynes, aldehydes and thiourea/urea

• Jie-Ping Wan,
• Yunfang Lin,
• Kaikai Hu and
• Yunyun Liu

Beilstein J. Org. Chem. 2014, 10, 287–292, doi:10.3762/bjoc.10.25

• ) [14] has been dominantly employed for DHPMs synthesis in both racemic [15][16][17][18] and asymmetric versions [19][20][21][22][23]. Despite of many recognized advantages of the Biginelli reaction, the product diversity suffered from limitations because β-ketoesters or 1,3-diketones are intrinsically

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• . 4.1 Alkylation of active methylene compounds Hydroalkylation of styrenes, indene and norbornene with 1,3-diketones was firstly reported in 2004 by using AuCl3 and AgOTf in 1:3 ratio as the catalyst (Scheme 15) [51]. The addition took place with Markovnikov selectivity in good yields, however optimal

• conditions suffered from severe limitations on 1,3-diketones as nucleophiles and unfunctionalized olefins. The same catalytic system was then employed with cyclic enols, dienes and trienes although lower yields were recorded [52]. Remarkably, the intramolecular [Au(I)]-catalyzed addition of β-keto amides to

• . Mechanistic proposal for the cooperative [Au(I)]/menthol catalysis for the enantioselective intramolecular hydroamination of dienes. [Au(III)]-catalyzed addition of 1,3-diketones to alkenes. [Au(I)]-catalyzed intramolecular addition of β-keto amides to alkenes. Intermolecular [Au(I)]-catalyzed addition of

Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

• Yumeng Xi,
• Boliang Dong and
• Xiaodong Shi

Beilstein J. Org. Chem. 2013, 9, 2537–2543, doi:10.3762/bjoc.9.288

• Yumeng Xi Boliang Dong Xiaodong Shi C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States 10.3762/bjoc.9.288 Abstract Gold-catalyzed O-vinylation of cyclic 1,3-diketones has been achieved for the first time, which provides direct

• 1,3-diketones with unactivated alkynes at ambient temperature. Results and Discussion As indicated in Scheme 1, the main challenge for the intermolecular O-nucleophile addition to alkynes is the competitive hydration side reaction. Although, theoretically, strictly anhydrous conditions shall prevent

• -cyclopentadione in DCM at room temperature. Finally and notably, all tested acyclic 1,3-diketones as well as 1,2-diketones gave no O-addition products under the current reaction conditions, likely caused by the intramolecular H-bonding. Conclusion In this letter, we report the first successful gold(I)-catalyzed

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

• Sudipta Pathak,
• Kamalesh Debnath and
• Animesh Pramanik

Beilstein J. Org. Chem. 2013, 9, 2344–2353, doi:10.3762/bjoc.9.269

• attention of synthetic as well as medicinal chemists [7][8][9]. Various methodologies for the synthesis of isocoumarins have been reported such as the reaction of o-halobenzoic acids and 1,3-diketones through a copper-catalyzed tandem sequential cyclization/addition/deacylation process [10][11], an iridium

Tandem dinucleophilic cyclization of cyclohexane-1,3-diones with pyridinium salts

• Mostafa Kiamehr,
• Firouz Matloubi Moghaddam,
• Satenik Mkrtchyan,
• Volodymyr Semeniuchenko,
• Linda Supe,
• Alexander Villinger,
• Peter Langer and
• Viktor O. Iaroshenko

Beilstein J. Org. Chem. 2013, 9, 1119–1126, doi:10.3762/bjoc.9.124

• afforded the desired products in good to excellent yields. It is worth mentioning that only cyclohexanediones were prone to reaction with the tested pyridinium salts with formation of the corresponding tetracyclic products 3, 4, 6 and 7. In the frame of the current project a variety of 1,3-diketones and

• CF3-containing 1,3-diketones were investigated, but these failed for all mentioned cases. For 3-cyanopyridinium salts a departure from the general trend was observed in terms of reaction conditions regarding the base used; here the highest efficiency was observed for NaHCO3, and the reaction took 4

• about reaction products is limited by the obscure structure of the real reaction product. In fact the reaction of pyridinium salt 2a with cyclic 1,3-diketones in the presence of either K2CO3 or DIPEA/KI yields an orange precipitate in acetonitrile. Redissolved in DMSO-d6, this precipitate gave rise to

Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

• Yan Sun,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 8–14, doi:10.3762/bjoc.9.2

• ] derivatives in moderate yields (Scheme 1a) [15]. In order to explore the generality of this four-component reaction, the reactivity of the other cyclic 1,3-diketones was also investigated. In an exploratory experiment, the four-component reaction of p-methoxyaniline, dimethyl acetylenedicarboxylate, 1-benzyl

• of spiro[dihydropyridine-oxindole] 1b. The two kinds of spiro compounds from reactions of isatins with arylamines and cyclic 1,3-diketones. Molecular structure of spiro[dihydropyridine-oxindole] 2f. Molecular structure of compound 3d. The four-component reactions containing dimedone (a) and

New efficient ligand for sub-mol % copper-catalyzed C–N cross-coupling reactions running under air

• Per-Fredrik Larsson,
• Peter Astvik and
• Per-Ola Norrby

Beilstein J. Org. Chem. 2012, 8, 1909–1915, doi:10.3762/bjoc.8.221

• when using higher catalytic loadings with secondary amine ligands [12][13]. Several classes of ligands have proved efficient in copper-catalyzed cross-coupling reactions, such as phenanthrolines, alpha-amino acids, 1,3-diketones, salicylamides, and imines, but DMEDA is one of the few that works well

Organic synthesis using (diacetoxyiodo)benzene (DIB): Unexpected and novel oxidation of 3-oxo-butanamides to 2,2-dihalo-N-phenylacetamides

• Wei-Bing Liu,
• Cui Chen,
• Qing Zhang and
• Zhi-Bo Zhu

Beilstein J. Org. Chem. 2012, 8, 344–348, doi:10.3762/bjoc.8.38

• acids can activate 1,3-diketones [40] to produce intermediate 5 and 6. This complexation not only increases the nucleophilicity of the methylene carbon atom, but also simultaneously increases the electrophilicity of the carbonyl carbon atom. Consequently, nucleophilic attack of the acetate ion on the

Regioselectivity in the multicomponent reaction of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal under controlled microwave heating

• Kamal Usef Sadek,
• Ramadan Ahmed Mekheimer,
• Tahany Mahmoud Mohamed,
• Moustafa Sherief Moustafa and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2012, 8, 18–24, doi:10.3762/bjoc.8.3

• investigation concerning the regioselectivity in multicomponent reactions of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal (DMFDMA) under controlled microwave heating. We began this study by treating 5-amino-3-methylpyrazole (1a) and dimedone (2a) with DMFDMA (3) in DMF under

• single-crystal X-ray diffraction [25][26] (Figure 1, Figure 2 and Table 1, Table 2, Table 3). With this result in hand, we went on to study the scope of such multicomponent reactions with several substituted 5-aminopyrazoles and cyclic 1,3-diketones. Thus, the reaction of 1b–f with 2a,b and 3, under the

• established by single-crystal X-ray diffraction of compounds 6e,g (Figure 3, Figure 4 and Table 3, Table 4) [27][28]. A proposed mechanism to account for the formation of products 6 is illustrated in Scheme 2. The base-catalyzed reaction of cyclic 1,3-diketones 2 with DMFDMA 3 gave the enaminone 7, which

Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination

• Jessica R. Breen,
• Graham Sandford,
• Dmitrii S. Yufit,
• Judith A. K. Howard,
• Jonathan Fray and
• Bhairavi Patel

Beilstein J. Org. Chem. 2011, 7, 1048–1054, doi:10.3762/bjoc.7.120

• derivatives were synthesised by sequential direct fluorination of appropriate 1,3-diketones and subsequent cyclisation of the in situ generated fluorodiketone with a hydrazine derivative. This represents the first example of a sequential, continuous flow gas/liquid–liquid/liquid process involving direct

• . Pyrazoles are also useful intermediates for many industrial products and it is, therefore, not surprising that many synthetic methods have been developed for the preparation of such heterocyclic systems, for example, through 1,3-dipolar cyclo-additions of diazo compounds and the direct condensation of 1,3

• -diketones and hydrazines [23]. However, the synthetic methodology for the preparation of the corresponding fluoropyrazole derivatives has not been developed to any great extent despite the potential use of such systems in life science applications. Recently, we explored direct fluorination of various

Photocycloaddition of aromatic and aliphatic aldehydes to isoxazoles: Cycloaddition reactivity and stability studies

• Axel G. Griesbeck,
• Marco Franke,
• Jörg Neudörfl and
• Hidehiro Kotaka

Beilstein J. Org. Chem. 2011, 7, 127–134, doi:10.3762/bjoc.7.18

• corresponding 1,3-diketones [13] or deaminated to yield Michael systems [14]. Thus, isoxazoles also appear to be important substrates for carbonyl–ene photocycloaddition due to possible applications in ring-opening transformations. Results and Discussion Synthesis of the isoxazole substrates The substrates

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• -substituted 1,3-diketones 17 and their derivatives are of great interest. Given that the alkylation typically requires stoichiometric amounts of a base and a toxic alkyl halide the development of an efficient environmentally benign route to 2-alkylated pentanediones 17a–c employing simply benzyl-, allyl- or

• formation of a quaternary carbon atom was possible. Although the product was isolated in lower yields (Scheme 17). Subsequently this method was expanded to other nucleophiles, such as 1,3-diketones [60]. Mirroring the Bi(OTf)3-catalyzed method, Hua et al. developed a BiCl3-catalyzed synthesis of 1,1