A convenient enantioselective decarboxylative aldol reaction to access chiral α-hydroxy esters using β-keto acids

• Zhiqiang Duan,
• Jianlin Han,
• Ping Qian,
• Zirui Zhang,
• Yi Wang and
• Yi Pan

Beilstein J. Org. Chem. 2014, 10, 969–974, doi:10.3762/bjoc.10.95

• ). Trace amount of side product acetophenone was formed through decarboxylative protonation of β-keto acid 1a, which was commonly observed in the case of chiral organic base catalysed decarboxylative additions. Further optimisation of the reaction conditions showed that CHCl3 was the best solvent choice in

Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine

• Fei Wang,
• Lingchun Li,
• Chuanfa Ni and
• Jinbo Hu

Beilstein J. Org. Chem. 2014, 10, 344–351, doi:10.3762/bjoc.10.32

• . Although a non-activated ketone such as acetophenone is unreactive under similar conditions, activated ketones could undergo this Wittig olefination reaction. Representative results for the olefination at a slightly elevated temperature (80 °C) are shown in Figure 2. A range of aryl trifluoromethyl (6a–d

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• , H2N–NH2 and OH−(H2O)7. Here, ketones are acetone and acetophenone. While routes of the ketone → hydrazone → diimine are similar, those from the diimines are different. From the isopropyl diimine, the N2 extrusion and the C–H bond formation takes place concomitantly. The concomitance leads to the

• product. For both ketone substrates, the diimines undergoing E2 reactions were found to be key intermediates. Keywords: acetone; acetophenone; DFT calculations; diimine intermediate; reduction reaction; transition states; Wolff–Kishner; Introduction The Wolff–Kishner (W-K) reduction is an organic

• mechanism variant or invariant with respect to the substrate, ketone or aldehyde? We addressed these questions by DFT calculations, which were carried out for two substrates, acetone and acetophenone. Reaction paths including proton transfers [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31

New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions

• Helge Klare,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2014, 10, 224–236, doi:10.3762/bjoc.10.18

• ; Chakravarty et al. [24] tested an ansa-bridged BINOL-based PV-cyclodiphosphazane in the asymmetric reduction of acetophenone with BH3 (5–8% ee), while Gade et al. [25] recently introduced BINOL-based PIII-cyclodiphosphazane ligands to transition-metal catalysis (up to 84% ee). We anticipated that by

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• reaction products were separated by column chromatography. 1-Hydroxy-1-phenylpentan-3-one (42) was isolated as a by-product in 16% yield [248]. The peroxidation of 1,4-dienes 43a,b with the Co(modp)2/Et3SiH/O2 system according to a similar reaction scheme gave dioxolanes 44a,b. Acetophenone (45) was

Efficient synthesis of dihydropyrimidinones via a three-component Biginelli-type reaction of urea, alkylaldehyde and arylaldehyde

• Haijun Qu,
• Xuejian Li,
• Fan Mo and
• Xufeng Lin

Beilstein J. Org. Chem. 2013, 9, 2846–2851, doi:10.3762/bjoc.9.320

• chemistry [5][6][7][8]. Recently, many one-pot variants of Biginelli-type reactions for the preparation of novel DHPMs using various active methylene compounds [9][10][11][12][13][14][15], such as enaminone, cyclic β-diketones, acetophenone, benzocyclic ketones and β-oxodithioesters etc., have also been

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• materials; for instance, anisole and chloro- or iodobenzene gave an ortho > para ≈ meta preferential order of substitution, while toluene, acetophenone, N,N-dimethylaniline or nitrobenzene afforded the para-substituted compound as the major product. The reaction could be monitored by EPR, which showed an

Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes

• Ana M. Sanjuán,
• Alberto Martínez,
• Patricia García-García,
• Manuel A. Fernández-Rodríguez and
• Roberto Sanz

Beilstein J. Org. Chem. 2013, 9, 2242–2249, doi:10.3762/bjoc.9.263

• )phenyllithium with geranyl bromide and 1n by two Wittig reactions from 2’-(phenylethynyl)acetophenone (see Supporting Information File 1). First, the hydroxycyclization of 1m, as a pure E isomer, under the previously established conditions afforded the dihydronaphthalene derivative 7m as a single isomer (Scheme

Regioselective carbon–carbon bond formation of 5,5,5-trifluoro-1-phenylpent-3-en-1-yne

• Motoki Naka,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2013, 9, 2182–2188, doi:10.3762/bjoc.9.256

• . Their proportion seemed to be affected by the bulky substituent and pivalaldehyde attained the higher ratio of 88%. Although 5 and 6 were obtained in 50 to 70% combined yields by the reaction with aldehydes, lower reactivity was displayed by the less electrophilic and more hindered acetophenone

An investigation of the observed, but counter-intuitive, stereoselectivity noted during chiral amine synthesis via N-chiral-ketimines

• Thomas C. Nugent,
• Richard Vaughan Williams,
• Andrei Dragan,
• Alejandro Alvarado Méndez and
• Andrei V. Iosub

Beilstein J. Org. Chem. 2013, 9, 2103–2112, doi:10.3762/bjoc.9.247

• hydrogenation catalyst or not), the cis/trans-imine ratios were found to be static in the aprotic reaction solvents we measured them in. Reduction of imines 2 The reported cis/trans ratio (5:95) for imine 2a [55][63][64], from acetophenone (1a), is very similar to our own measurement (6:94). (Regarding the

• ratio assessment is to compare the two down field quartets originating from the PEA auxiliary. See the 1H NMR data for imine 4a (Table 1) of ref [47]. Hogeveen reduced the (S)-N-phenylethylimine of acetophenone with Pd-C/H2 and recorded a 70% de. This is much lower than what we and others have observed

Raman spectroscopy as a tool for monitoring mesoscale continuous-flow organic synthesis: Equipment interface and assessment in four medicinally-relevant reactions

• Trevor A. Hamlin and
• Nicholas E. Leadbeater

Beilstein J. Org. Chem. 2013, 9, 1843–1852, doi:10.3762/bjoc.9.215

• effect on the outcome of the reaction (Table 2, entries 3 and 4). The Claisen–Schmidt condensation We moved next to study the Claisen–Schmidt condensation of benzaldehyde with acetophenone to yield chalcone (Scheme 3). Chalcones display interesting biological properties such as antioxidant, cytotoxic

• (CH), 129.74 (CH), 130.93 (CH), 133.17 (C), 134.88 (C), 141.48 (CH), 168.00 (C), 194.87 (C) [54]. Typical procedure for monitoring the Claisen–Schmidt reaction Into a 50 mL volumetric flask was added 4-fluorobenzaldehyde (1.551 g, 12.5 mmol, 1 equiv) and acetophenone (1.637 g, 12.5 mmol, 1 equiv

• = 10 s). Monitoring the conversion of benzaldehyde with acetophenone to chalcone, 3a, across a range of reaction conditions (scan time = 15 s, integration = 10 s). Monitoring the conversion of benzaldehyde, ethyl acetoacetate, and urea to 5-ethoxycarbonyl-6-methyl-4-phenyl-3,4-dihydropyrimidin-2(1H

Total synthesis of ochnaflavone

• Monica M. Ndoile and
• Fanie R. van Heerden

Beilstein J. Org. Chem. 2013, 9, 1346–1351, doi:10.3762/bjoc.9.152

• formation of the chalcone by an aldol condensation reaction with a suitably substituted acetophenone. Selective methylation of 2,4,6-trihydroxyacetophenone with methyl iodide yielded 2'-hydroxy-4',6'-dimethoxyacetophenone (5) in moderate yield. The Claisen–Schmidt condensation of 5 with diaryl ether 4 under

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• acetophenone [33]. Among the different AQ derivatives that were tested, 1,4-diamino-2,3-dichloro-antraquinone (DADCAQ) was the most effective in terms of both conversion and selectivity of the ketone product. The potential of this catalytic system was proved by extending its application, in the absence of

• hydrocarbons, Xu and co-workers developed other redox initiators in addition to the NHPI/quinone systems previously described. In 2005 they reported the selective oxygenation of ethylbenzene to the corresponding acetophenone by means of a NHPI/o-phenanthroline-mediated organocatalytic system, in the presence

• described above led to the formation of acetophenone as the major product of ethylbenzene oxidation. A different result was achieved by Fierro et al. who, in the same year, reported the ethylbenzene oxidation to its hydroperoxide by operating in the presence of NHPI (or other NHIs, i.e., N

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• and [11C]-labeled chalcones 19a and 19b were synthesized using similar methods, and a representative synthesis of 19a is shown (Scheme 2B). Aldol condensation between the appropriate acetophenone 22 and benzaldehyde 23 afforded the chalcone backbone, which was subsequently pegylated to give 24 and

Enantioselective reduction of ketoimines promoted by easily available (S)-proline derivatives

• Martina Bonsignore,
• Maurizio Benaglia,
• Laura Raimondi,
• Manuel Orlandi and
• Giuseppe Celentano

Beilstein J. Org. Chem. 2013, 9, 633–640, doi:10.3762/bjoc.9.71

• testing the commercially available N-Boc-L-proline (1) as catalyst in the reduction of ketimines with trichlorosilane. The imines were typically prepared with a microwave-promoted reaction between acetophenone and the aromatic amine in toluene in the presence of K10 clay as activator. The first screening

• thionyl chloride under reflux for 4 hours. The catalytic efficiency of these catalysts was evaluated in the stereoselective reduction of the N-phenyl imine of acetophenone (Table 2). After running the reaction in dichloromethane at 0 °C for 18 hours, all the catalysts afforded the desired product in

• substituted imines (Table 3). Catalyst 5 showed a good chemical activity, promoting the enantioselective reduction in yields up to 88%, except when a very bulky protecting group was used (Table 3, entry 4). In the reaction of both N-Ph and N-PMP imines derived from acetophenone a discrete level of

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• . The enolates and their equivalents involved in the reactions discussed in this article were derived from ketones, nitroalkanes, malononitrile and α,β-unsaturated compounds. Keywords: acetophenone; chromane; enolates; malononitrile; Michael addition; salicylaldehyde; Introduction The chromane

• from acetophenone (7) has been employed by a number of chemists in the synthesis of flavans and flavones. Flavans are chromane derivatives with a C-2 phenyl substituent while flavones are chromane derivatives with a carbonyl functional group at C-4, a carbon–carbon double bond between C-2 and C-3, and

• a C-2 phenyl substituent. The synthesis of flavans and flavones generally involves treatment of acetophenone (7) with a base to give enolate 8, which undergoes a Knoevenagel condensation with salicylaldehyde (5) to yield a chalcone 9. These chalcone derivatives are then cyclized by using various

Design and synthesis of quasi-diastereomeric molecules with unchanging central, regenerating axial and switchable helical chirality via cleavage and formation of Ni(II)–O and Ni(II)–N coordination bonds

• Vadim A. Soloshonok,
• José Luis Aceña,
• Hisanori Ueki and
• Jianlin Han

Beilstein J. Org. Chem. 2012, 8, 1920–1928, doi:10.3762/bjoc.8.223

• of target complexes 19/20. It is interesting to note that the acetophenone module-derived compound 14a gave the expected enolate 16a; however, its further oxidation lead mostly to decomposition, suggesting higher instability of intermediate derivatives of type 17 and 18 [48]. Also, the benzophenone

Palladium-catalyzed substitution of (coumarinyl)methyl acetates with C-, N-, and S-nucleophiles

• Kalicharan Chattopadhyay,
• Erik Fenster,
• Alexander J. Grenning and
• Jon A. Tunge

Beilstein J. Org. Chem. 2012, 8, 1200–1207, doi:10.3762/bjoc.8.133

• conditions (5 mol % Pd(PPh3)4, MeCN, rt, Table 1, entry 3), a variety of enolate nucleophiles could be selectively coupled with coumarin electrophiles (Scheme 2). For example, acetone, acetophenone and 1,1,1-trimethylacetone enolates can all be generated and coupled with the coumarin electrophile

Volatile organic compounds produced by the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria 85-10

• Teresa Weise,
• Marco Kai,
• Anja Gummesson,
• Armin Troeger,
• Stephan von Reuß,
• Silvia Piepenborn,
• Francine Kosterka,
• Martin Sklorz,
• Ralf Zimmermann,
• Wittko Francke and
• Birgit Piechulla

Beilstein J. Org. Chem. 2012, 8, 579–596, doi:10.3762/bjoc.8.65

• -methylbutyl propionate (14), and the corresponding 2-methylbutyl esters 5 and 13 as well as 3-methylbutyl 3-methylbutyrate (19) could be identified. Trace amounts of benzylalcohol (18), acetophenone (20) and 2-phenylethanol (23) and its acetate (29) along with the three alkylated pyrazines 8, 16, 33 were the

Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

• M. Isabel Burguete,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159

• reported by Poliakoff and Sheldon involving two sequential reactions (Scheme 8) [94]. In that case, the first step was the continuous hydrogenation of acetophenone to afford the racemic phenylethanol with Pd supported on SiO2/Al2O3 as the catalyst and scCO2 as the reaction medium (150–200 °C, 10 MPa, 1.1

• . Enantioselective hydroformylation of styrene. Enantioselective hydrovinylation of styrene. Enantioselective cyclopropanation of styrene catalyzed by supported Cu–BOX, Cu–PyOX and Rh–PyBOX catalysts. Continuous hydrogenation of acetophenone coupled with the kinetic resolution of the product. Kinetic resolution of

Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine, histidine and tryptophan

• Axel G. Griesbeck,
• Jörg Neudörfl and
• Alan de Kiff

Beilstein J. Org. Chem. 2011, 7, 518–524, doi:10.3762/bjoc.7.60

• temperature and in ethanol at low temperatures are known: Triplet acetone, acetophenone and xanthone in acetonitrile are quenched by 1 via energy transfer; the rate constant is almost diffusion-controlled and somewhat smaller for benzophenone. The sole product from the photolysis of 1 is the double hydrogen

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

• of aci-nitroethane 1 (Scheme 1). The reaction of acetylacetaldehyde with hydroxylamine gave 7b, exclusively. 3,5-Diphenylisoxazole (7f) was prepared from acetophenone and methyl benzoate, followed by cyclization of the resulting diketone 4 with hydroxylamine. 5-Methoxy-3-phenylisoxazole (7g) and 5

• , CH3), 20.9 (1C, CH3), 12.2 (1C, CH3). 1H NMR (300 MHz, CDCl3): 3.59 (q, 1H, 3J = 7.2 Hz, CH), 2.06 (s, 6H, 2 × CH3), 1.97 (s, 3H, CH3), 1.70 (s, 1.5H, CH3), 1.19–1.16 (d, 3H, 3J = 6.9 Hz, CH3). 1,3-Diphenylpropane-1,3-dione (4). A mixture of acetophenone (30.04 g, 0.25 mol, 29.2 mL), methyl benzoate

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• , 354.1287. 4-(2-Triphenylenylethynyl)acetophenone (1d). The crude product was purified by column chromatography with a mixture of hexane and dichloromethane (4:1, v/v) as eluant to yield 1d as a colorless solid (0.506 g, 72%), mp 181–183 °C; IR (neat) 3067, 2218, 1669 cm−1; 1H NMR (CDCl3, 400 MHz) δH = 8.86

Systematic investigations on the reduction of 4-aryl-4-oxoesters to 1-aryl-1,4-butanediols with methanolic sodium borohydride

• Subrata Kumar Chaudhuri,
• Manabendra Saha,
• Amit Saha and
• Sanjay Bhar

Beilstein J. Org. Chem. 2010, 6, 748–755, doi:10.3762/bjoc.6.94

• protic polar co-solvents with different product distributions depending upon the nature of the co-solvent (Table 2). Compounds 1a, 3, acetophenone and butyrophenone were individually subjected to reduction in ether (Table 3) in the presence of MeOH (2 equiv) for a limited period of time (1 h). It was

Concise methods for the synthesis of chiral polyoxazolines and their application in asymmetric hydrosilylation

• Wei Jie Li,
• Zun Le Xu and
• Sheng Xiang Qiu

Beilstein J. Org. Chem. 2010, 6, No. 29, doi:10.3762/bjoc.6.29

• explored (Table 2 and Table 3). The reduction of acetophenone was first examined, since this is often used as the standard ketone in investigations of asymmetric hydrosilylation. The reaction of acetophenone with diphenylsilane in the presence of polyoxazolines 1–7 and [Rh(COD)Cl]2 was studied (Table 2

• temperature was raised to −5 °C, the acetophenone disappeared completely within 72 h to afford 1-phenylethanol in a yield of 86% with 89% ee (entry 2). As the temperature was raised to room temperature, the reaction was accelerated further, but the ee was slightly lower (entry 3). Therefore, the reaction

• , exceeding that observed in either CCl4 or CH3OH (entries 2, 4 and 5). Catalyst concentrations were generally employed at 2 mol %, relative to acetophenone (entry 2), although loadings as low as 0.5 mol % could be used, a longer reaction time was required (entry 8). However, whereas a higher catalyst loading