On Reuben G. Jones synthesis of 2-hydroxypyrazines

• Pierre Legrand and
• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 935–943, doi:10.3762/bjoc.18.93

• text describes some insights and improvements, such as the unprecedented use of tetraalkylammonium hydroxide, in the reaction parameters affecting the regioselectivity and yield when starting from phenylglyoxal and two α-aminoamides. We also suggest a mechanism explaining the counterintuitive

• occurrence of 3,5-substituted-2-hydroxypyrazine as the major reaction product. Keywords: α-aminoamide; condensation; hydroxypyrazine; methylglyoxal; phenylglyoxal; Introduction In a recent report [1], the many ways a pyrazine nucleus is able to interact with proteins were reviewed. In this text, it was

• 2-hydroxypyrazines 3 and/or 4 [5][6]. This discovery, possibly inspired by the contemporary base-promoted condensation between phenylglyoxal and aminoguanidine to give 3-amino-1,2,4-triazines [7][8]. remains on paper, the easiest access to 2-hydroxypyrazines [9][10][11][12]. Moreover, this synthesis

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• components (Scheme 2). The product 8a obtained from benzoic acid, phenylglyoxal, benzylamine, and tert-butyl isocyanide was selected for the screening of the reaction parameters (Table 3). The overall process was conducted in a two-step one-pot fashion as was originally designed by Shibata. In the first step

Asymmetric synthesis of CF₂-functionalized aziridines by combined strong Brønsted acid catalysis

• Xing-Fa Tan,
• Fa-Guang Zhang and
• Jun-An Ma

Beilstein J. Org. Chem. 2020, 16, 638–644, doi:10.3762/bjoc.16.60

• hinges upon the discovery of a combined strong Brønsted acid system comprised of a chiral disulfonimide and 2-carboxyphenylboronic acid. Results and Discussion We commenced the desired one-pot transformation by conducting the model reaction between phenylglyoxal monohydrate (1a), 4-methoxyaniline (2a

• dr values, including alkyl or halogen-substituted phenyl and 2-naphthyl ketones (Scheme 2). Unfortunately, phenylglyoxal monohydrates bearing strong electron-withdrawing groups were not compatible with the current conditions. X-ray analysis of aziridine 4a confirmed the absolute configuration of the

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• explored for tetrasubstituted imidazole synthesis from primary amines, aromatic aldehydes, ammonium acetate, and phenylglyoxal. The TFE-modified SMSM had better behavior than others. To highlight the catalytic activity of the RFOH/SBA-15-Pr-SO3H, the reaction was also carried out with non-RFOH

Iodine-mediated synthesis of 3-acylbenzothiadiazine 1,1-dioxides

• Long-Yi Xi,
• Ruo-Yi Zhang,
• Lei Shi,
• Shan-Yong Chen and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2016, 12, 1072–1078, doi:10.3762/bjoc.12.101

• ). To shed light on the mechanism of this reaction, a control experiment was conducted. It is known that acetophenones can undergo halogenation and further Kornblum oxidation to give phenylglyoxal in a I2/DMSO system [33][34]. We isolated the product in 85% yield by heating phenylglyoxal and 2a in DMSO

• at 110 °C for 24 h without I2 (Scheme 6). To further probe the reaction process, we monitored the reaction system at 80 °C by 1H NMR spectroscopic studies. A signal appeared at 9.63 ppm, which was assigned to phenylglyoxal [35] (see Supporting Information File 1). Moreover, intermediate D was

• isolated after stirring 12 h at 80 °C. On the basis of this experiment described above and literature [13][35][36], a possible mechanism was proposed in Scheme 7. The halogenation of 1a with iodine results in the formation of compound A, which, via Kornblum oxidation, provides phenylglyoxal B. The

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels–Alder reactions

• Salah Fadel,
• Youssef Hajbi,
• Mostafa Khouili,
• Said Lazar,
• Franck Suzenet and
• Gérald Guillaumet

Beilstein J. Org. Chem. 2014, 10, 282–286, doi:10.3762/bjoc.10.24

• Paudler [34][50], i.e., the phenylglyoxal was condensed with the S-methylthiosemicarbazide followed by an oxidation reaction with MCPBA. Synthesis of N-substituted pent-4-ynamides N-Alkyl or N-aryl-pent-4-ynamides were prepared by amide coupling reactions between pent-4-ynoic acid and various amines in

• ) phenylglyoxal, Na2CO3, H2O, 5 °C, 6 h (96%); (c) MCPBA, CH2Cl2, rt, 4 h (82%). Coupling of pent-4-ynoic acid with different amines. Conditions: (a) EDCI, DMAP, THF, rt, 36 h. Reaction of triazine 1 with different pent-4-ynamides. Conditions: n-BuLi, THF, −30 °C, 2 h. Reaction of triazines 6–9 under microwave