High-speed C–H chlorination of ethylene carbonate using a new photoflow setup

• Takayoshi Kasakado,
• Takahide Fukuyama,
• Tomohiro Nakagawa,
• Shinji Taguchi and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2022, 18, 152–158, doi:10.3762/bjoc.18.16

• Research & Development Group, Nankai Chemical Co. Ltd., 1-1-38 Kozaika, Wakayama 641-0007, Japan Department of Applied Chemistry, National Yang Ming Chiao Tung University (NYCU), Hsinchu 30010, Taiwan 10.3762/bjoc.18.16 Abstract We report the high-speed C–H chlorination of ethylene carbonate, which gives

• ethylene carbonate was introduced to the reactor, the residence time was measured to be 15 or 30 s, depending on the slope of the reactor set at 15 or 5°, respectively. Such short time of exposition sufficed the photo C–H chlorination. The partial irradiation of the flow channels also sufficed for the C–H

• of ethylene carbonate such as 61%, the selectivity for monochlorinated ethylene carbonate over dichlorinated ethylene carbonate was 86%. We found that the substrate contamination with water negatively influenced the performance of the C–H chlorination. Keywords: C–H chlorination; chlorine gas

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• prepared a library of monobrominated compounds using this simple yet effective strategy. A plausible mechanism is shown in Figure 21. Chlorination of arenes with Mes-Acr-MeClO4 (2): Ohkubo et al. observed that only under aerobic photocatalytic conditions, C–H chlorination of trimethoxybenzene (TMB) occurs

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

• rate-limiting step. In 2011, Cheng and co-workers discovered an alternative route of a C–H chlorination protocol of 2-arylpyridines by employing acyl chlorides 6 as chlorinating reagents [33]. A range of mono-chlorinated 2-arylpridines 2 were obtained in the presence of Cu(OAc)2 and Li2CO3 under O2

• atmosphere (Scheme 2). In the same year, Shen and co-workers reported the Cu-catalyzed sp2 C–H chlorination of 2-arylpyridines by using the salt LiCl as a new chlorine source in the presence of CrO3 and Ac2O [34]. Due to the oxidizing potency of the CrO3, the application scope of the method was not broad

• since low selectivity between monochlorinated products 2 and dichlorinated products 7 was suffered (Scheme 3). Two years later, the same group developed a modified approach for this kind of C–H chlorination by employing lithium halide (LiCl or LiBr) as the source of halogen to react with 2-arylpyridine

Copper-catalyzed aerobic aliphatic C–H oxygenation with hydroperoxides

• Pei Chui Too,
• Ya Lin Tnay and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2013, 9, 1217–1225, doi:10.3762/bjoc.9.138

• envision employing hydroperoxides as precursors for O-radicals in the presence of Cu salts. The lower valent Cu(I) species could potentially undergo single-electron reduction of hydroperoxides to produce the corresponding O-radicals [10][11][12][13]. Ball recently reported CuCl-catalyzed aliphatic C–H

• chlorination using hydroperoxides as the O-radical source, in which the C-radicals generated by the 1,5-H radical shift were chlorinated (Scheme 2a) [14]. If reductive generation of the O-radicals from hydroperoxides could be achieved under an O2 atmosphere, the C-radicals generated by 1,5-H radical shift