β-Amino functionalization of cinnamic Weinreb amides in ionic liquid

• Yi-Ning Wang,
• Guo-Xiang Sun and
• Gang Qi

Beilstein J. Org. Chem. 2016, 12, 2372–2377, doi:10.3762/bjoc.12.231

• , Grignard and organolithium reagents or ester enolates, the Weinreb amides can be easily converted into aldehydes, ketones, and β-keto esters, respectively [13][14][15][16][17][18][19][20]. Therefore, the transformation of β-amino Weinreb amides can provide a promising pathway towards the achievement of β

Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions

• José M. Andrés,
• Miriam Ceballos,
• Alicia Maestro,
• Isabel Sanz and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2016, 12, 628–635, doi:10.3762/bjoc.12.61

• -diketones. Reaction of nitrostyrenes with β-keto esters and β-dicarbonyl compounds. Reaction of nitrostyrenes with α-nitrocyclohexanone and ethyl α-nitropropionate. Screening of catalysts and optimization of the reaction conditions for the additions of diethyl malonate and ethyl 2-oxocyclopentanecarboxylate

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• chirally pure α-amino ketones formed in this reaction are valuable building blocks in organic synthesis [37]. The NHC generated from the bicyclic pentafluoro triazolium salt promoted the chemoselective cross aza-benzoin reaction of aldehydes with N-PMP-imino esters to afford α-amino-β-keto esters in good

Asymmetric α-amination of β-keto esters using a guanidine–bisurea bifunctional organocatalyst

• Minami Odagi,
• Yoshiharu Yamamoto and
• Kazuo Nagasawa

Beilstein J. Org. Chem. 2016, 12, 198–203, doi:10.3762/bjoc.12.22

• Minami Odagi Yoshiharu Yamamoto Kazuo Nagasawa Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei city, 184-8588, Tokyo, Japan 10.3762/bjoc.12.22 Abstract An asymmetric α-amination of β-keto esters with azodicarboxylate in the

• presence of a guanidine–bisurea bifunctional organocatalyst was investigated. The α-amination products were obtained in up to 99% yield with up to 94% ee. Keywords: α-amination; bifunctional catalyst; guanidine; hydrogen-bonding catalyst; urea; Introduction Asymmetric α-amination of β-keto esters is an

• particular, catalytic asymmetric α-amination of β-keto esters has been widely explored, using both metal catalysts and organocatalysts [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. We have developed a series of guanidine–bis(thio)urea bifunctional organocatalysts, and have used them in a variety of

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

• -workers [71] successfully achieved the selective mono-α-chlorination of β-keto esters/amides and 1,3-diketone 78 by employing an electrochemical synthesis via a catalysis by means of Cu(OTf)2. The synthesis of chlorinated carbonyl products 79 were acquired in a divided cell using aqueous HCl as chlorine

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• through a radical mechanism [194]. The Bu4NI/t-BuOOH system was employed also in the oxidative coupling of carboxylic acids with β-keto esters [195]. The cross-dehydrogenative C–O coupling of alcohols 201 and ketones 202 in the presence of the Bu4NI/t-BuOOH system was accomplished to prepare α-acyloxy

• , or copper) were performed with cyclohexanone, 2-methylcyclohexanone, cyclohexene, 1-octene, cumene, xylene, dimethylaniline, and dioxane [201]. The enantioselective oxidative coupling of 2,6-dialkylphenyl-β-keto esters and thioesters 215 with tert-butyl hydroxycarbamate 216 was performed using the Cu

• system; different β-keto esters and hydroxamic acid derivatives can be used [203]. The acetoxylation at the α’-position of α,β-unsaturated ketones with Mn(OAc)3 was studied in detail. It is suggested that manganese(III) acetate causes the generation of C-radicals from ketones followed by the

Organocatalytic asymmetric fluorination of α-chloroaldehydes involving kinetic resolution

• Kazutaka Shibatomi,
• Takuya Okimi,
• Yoshiyuki Abe,
• Akira Narayama,
• Nami Nakamura and
• Seiji Iwasa

Beilstein J. Org. Chem. 2014, 10, 323–331, doi:10.3762/bjoc.10.30

• α-chloro-α-fluoro-β-keto esters via the sequential chlorination–fluorination of β-keto esters with the Cu(II) complex of SPYMOX [9], a spiro chiral oxazoline ligand developed by our research group [9][10][11][12]. In that study, we succeeded in determining the absolute stereochemistry of the α

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

Asymmetric allylic alkylation of Morita–Baylis–Hillman carbonates with α-fluoro-β-keto esters

• Lin Yan,
• Zhiqiang Han,
• Bo Zhu,
• Caiyun Yang,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2013, 9, 1853–1857, doi:10.3762/bjoc.9.216

• and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 10.3762/bjoc.9.216 Abstract In the presence of a commercially available Cinchona alkaloid as catalyst, the asymmetric allylic alkylation of Morita–Baylis–Hillman carbonates, with α-fluoro-β-keto esters as

• ). Keywords: allylic alkylation; asymmetric catalysis; fluorine; fluoro-β-keto esters; Morita–Baylis–Hillman carbonates; natural product; Introduction Fluorine is the most electronegative element in the periodic table, resulting in a highly polar C–F bond. This gives fluoro-organic compounds unique

Ethyl diazoacetate synthesis in flow

• Mariëlle M. E. Delville,
• Jan C. M. van Hest and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2013, 9, 1813–1818, doi:10.3762/bjoc.9.211

• variety of reactions e.g. cyclopropanation, X–H insertion, cycloaddition and ylide formation [13][15], and more recently, in the synthesis of valuable compound classes such as β-keto esters [16] and β-hydroxy-α-diazocarbonyl compounds [17], we aimed to develop an inherently safe continuous-flow EDA

N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters

• Takuya Uno,
• Yusuke Kobayashi and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2012, 8, 1499–1504, doi:10.3762/bjoc.8.169

• Takuya Uno Yusuke Kobayashi Yoshiji Takemoto Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan 10.3762/bjoc.8.169 Abstract An efficient catalytic synthesis of α-amino-β-keto esters has been newly developed. Cross-coupling of various aldehydes

• with α-imino ester, catalyzed by N-heterocyclic carbene, leads chemoselectively to α-amino-β-keto esters in moderate to good yields with high atom efficiency. The reaction mechanism is discussed, and it is proposed that the α-amino-β-keto esters are formed under thermodynamic control. Keywords: α

• -amino-β-keto esters; cross-aza-benzoin; α-imino ester; N-heterocyclic carbenes; organocatalysis; umpolung reactions; Introduction α-Amino-β-keto ester derivatives are one of the fundamental structural subunits in natural products such as miuraenamides [1], and important building blocks for the

PEG-embedded KBr₃: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

• Sanny Verma,
• Suman L. Jain and
• Bir Sain

Beilstein J. Org. Chem. 2011, 7, 1334–1341, doi:10.3762/bjoc.7.157

• conditions (see Experimental). The reaction proceeded efficiently and afforded a high product yield under mild reaction conditions. These successful results prompted us to extend the scope of the reaction with a variety of aldehydes, substituted anilines and β-keto esters under identical reaction conditions

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• % yield [17]. In 2008–2009, we found that chiral nonracemic cinchona alkaloids and guanidines act as Brønsted bases to generate ammonium or guanidinium enolates for the enantioselective electrophilic trifluoromethylation of β-keto esters with Umemoto reagents with good enantioselectivities in the range 60

• with Ruppert’s reagent (Scheme 27) [33]. These reagents are shelf-stable, non-explosive under ambient conditions but should not be heated as solid materials. These new electrophilic trifluoromethylating reagents were initially evaluated in reactions with carbonyl compounds such as β-keto esters and α

• -nitro esters. In particular, reagent 37 was found to be an effective trifluoromethylating agent. Under phase-transfer catalysis the β-keto esters derived from indanone, tetralone and pentanone in the presence of 37 gave the corresponding trifluoromethylated product in 42–67% yields. The new reagents

DBFOX- Ph/metal complexes: Evaluation as catalysts for enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones

• Takehisa Ishimaru,
• Norio Shibata,
• Dhande Sudhakar Reddy,
• Takao Horikawa,
• Shuichi Nakamura and
• Takeshi Toru

Beilstein J. Org. Chem. 2008, 4, No. 16, doi:10.3762/bjoc.4.16

• fluorination of a wide range of substrates, including β-keto esters, β-keto phosphonates, oxindoles [38][40][43][51][53][56][57]. They have also recently reported the enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones with their extended catalytic system, NiCl2-BINAP/R3SiOTf-lutidine with high

• -thiazolidinones with N-fluorobenzenesulfonimide (NFSI) (Figure 1). Results and Discussion Our previous studies of the DBFOX-Ph/Ni(II)-catalyzed enantioselective fluorination of β-keto esters have shown that the optimal reaction conditions require NFSI as the fluorine source and a catalytic amount of Ni(ClO4)2