Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Oligomerization of optically active N-(4-hydroxyphenyl)mandelamide in the presence of β-cyclodextrin and the minor role of chirality

• Helmut Ritter,
• Antonia Stöhr and
• Philippe Favresse

Beilstein J. Org. Chem. 2014, 10, 2361–2366, doi:10.3762/bjoc.10.246

• The chiral N-(4-hydroxyphenyl)mandelamide (1) was synthesized through condensation of p-aminophenol with (R)- or (S)-mandelic acid, respectively in presence of dicyclohexylcarbodiimide as condensing agent. For oligomerization of 1 via oxidative coupling laccase from Pleurotus ostreatus, peroxidase

• converted with both enzymes. However this preference is very low in all cases. Experimental Materials Horseradish peroxidase practical grade I (370,2 U/mg) was purchased from Appli Chem and Laccase from pleurotus ostreatus (9,4 U/mg) from Sigma-Aldrich. p-Aminophenol was bought from Grüssing, N,N

• acetone and cooled in an ice–water bath. Subsequently, a suspension of 10.32 g (50 mmol) dicyclohexylcarbodiimide in 50 mL acetone was added and the reaction mixture stirred for 2.5 hours at 0 °C. After that, 5.46 g (50 mmol) p-aminophenol was added and the ice bath was removed. The reaction mixture was

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p

• -nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of

• was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid. Keywords: catalytic tubular reactor; flow chemistry; formic acid; hydrogenation; p-aminophenol; p-nitrophenol; Introduction The flow reaction process enables

An aniline dication-like transition state in the Bamberger rearrangement

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

Beilstein J. Org. Chem. 2013, 9, 1073–1082, doi:10.3762/bjoc.9.119

• p-aminophenol was investigated by DFT calculations for the first time. The nitrenium ion, C6H5–NH+, suggested and seemingly established as an intermediate was calculated to be absent owing to the high nucleophilicity of the water cluster around it. First, a reaction of the monoprotonated system, Ph

• protonated p-aminophenol could not be obtained, probably owing to the limited size of the reaction system. TS2(I, 3H2O) and TS2(I, [1,3]-shift) were also obtained and are shown at the end of Figure S3. Here, TS2(I, 2H2O), TS2(I, 3H2O) and TS2(I, [1,3]-shift) correspond to three TS2s in Figure S2

• basis that treatment of 1 in H2[18O]H2SO4 provides an [18O]-incorporated p-aminophenol, 2a. A reaction of N-ethyl-N-phenylhydroxylamine, which demonstrates that the Bamberger rearrangement does not take the route of the direct [1,5]-OH shift. A mechanism involving the nitrenium-ion intermediate 7. 8a is

Synthesis and characterization of new diiodocoumarin derivatives with promising antimicrobial activities

• Hany M. Mohamed,
• Ashraf H. F. Abd EL-Wahab,
• Ahmed M. EL-Agrody,
• Ahmed H. Bedair,
• Fathy A. Eid,
• Mostafa M. Khafagy and
• Kamal A. Abd-EL-Rehem

Beilstein J. Org. Chem. 2011, 7, 1688–1696, doi:10.3762/bjoc.7.199

• compounds 3 and 7 showed the corresponding molecular ion peaks at m/z 460 (M+, 2.6%) and m/z 469 (M+, 18.5%). The fragmentation pattern of compounds 3 and 7 are illustrated in Scheme 2. Reactions of 3 with 4-aminophenylethanol or p-aminophenol, or with potentially bifunctional amino acids (anthranilic acid

• –11 To a well-stirred solution of 3 (0.46 g, 1 mmol) in dry dichloromethane (DCM) containing a few drops of triethylamine (TEA) an equivalent amount of an ambient nucleophile [4-aminophenylethanol, p-aminophenol, anthranilic acid and p-aminophenylacetic acid (1.2 mmol)] was added. The reaction mixture