Photochemical Organocatalytic Aerobic Cleavage of C=C Bonds Enabled by Charge-Transfer Complex Formation
Yi-Xuan Chen, Jun-Tao He, Mei-Chun Wu, Zhi-Lin Liu, Kai Tang, Peng-Ju Xia, Kai Chen, Hao-Yue Xiang*, Xiao-Qing Chen* and Hua Yang*
*College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P.R.
China, Email: xianghaoyue
csu.edu.cn, xqchencsu.edu.cn,
hyangchemcsu.edu.cn
Y.-X. Chen, J.-T. He, M.-C. Wu, Z.-L. Liu, K. Tang, P.-J. Xia, K. Chen, H.-Y. Xiang, X.-Q. Chen, H. Yang, Org. Lett., 2022, 24, 3920-3925.
DOI: 10.1021/acs.orglett.2c01192
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Abstract
Sodium benzene sulfinate catalyzed a visible-light-driven aerobic oxidative cleavage of olefins to provide the corresponding aldehydes and ketones under transition-metal-free conditions. Notably, α-halo-substituted styrenes proceeded with photoinduced oxidation to finally afford α-halo-acetophenones with halogen migration.
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proposed mechanism
Details
The document describes a novel visible-light-driven organocatalytic protocol for the aerobic oxidative cleavage of olefins, facilitated by sodium benzene sulfinate. This method efficiently converts alkenes into aldehydes and ketones under transition-metal-free conditions, utilizing molecular oxygen as a clean and cost-effective oxidant. The key to this process is the formation of charge-transfer complexes between sodium benzene sulfinate and molecular O2, which generates sulfonyl radicals under mild conditions. The study highlights the method's broad substrate tolerance, including various substituted styrenes and vinyl halides, yielding the desired carbonyl compounds in moderate to excellent yields. The protocol avoids the use of expensive and toxic oxidants, aligning with sustainable chemistry principles. Mechanistic investigations suggest the involvement of radical species and the formation of a dioxetane intermediate. The method's practical applicability is demonstrated through scale-up reactions and its compatibility with complex molecules, including natural product derivatives and drug molecules. This work offers a promising, environmentally friendly alternative to traditional oxidative cleavage methods, with potential applications in synthetic chemistry and the chemical industry.
Key Words
aldehydes, ketones, α-bromoketones, α-iodoketones, organocatalysis, photochemistry, oxygen
ID: J54-Y2022
