- Facile Synthesis of α-Haloketones by Aerobic Oxidation of Olefins Using KX as Nonhazardous Halogen Source
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An operationally simple and safe synthesis of α-haloketones using KBr and KCl as nonhazardous halogen sources is reported. It involves an iron-catalysed reaction of alkenes with KBr/KCl using O2 as terminal oxidant under the irradiation of visible-light. This strategy avoids the risks associated with handling halo-contained electrophiles (Cl2, Br2, NCS, NBS). The process is tolerant to several functional groups, and extended to a range of substituted styrenes in up to 89% yield. A radical reaction pathway is proposed based on control experiments and spectroscopy studies.
- Luo, Zhibin,Meng, Yunge,Gong, Xinchi,Wu, Jie,Zhang, Yulan,Ye, Long-Wu,Zhu, Chunyin
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supporting information
p. 173 - 177
(2020/01/02)
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- One-Pot Preparation of Aromatic Amides, 4-Arylthiazoles, and 4-Arylimidazoles from Arenes
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Simple treatment of arenes with α-bromoacetyl chloride and AlCl3, followed by the reaction with molecular iodine and aq. NH3, thioamides, or amidines gave the corresponding primary aromatic amides, 4-arylthiazoles, or 4-arylimidazoles in good yields, respectively. Aryl α-bromomethyl ketones are the key intermediates in those reactions. Primary aromatic amides were formed from arenes through the reaction of aryl α-bromomethyl ketones with molecular iodine and aq. NH3, and 4-arylthiazoles and 4-arylimidazoles were formed from arenes through the reactions of aryl α-bromomethyl ketones with thioamides and amidines, respectively, in one pot under transition-metal-free conditions.
- Yamamoto, Takahiro,Togo, Hideo
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p. 4187 - 4196
(2018/08/21)
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- Deacetalization by photoinduced electron transfer with a pyrylium salt: Effect of limiting the amounts of water, oxygen and sensitizer
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The photodeacetalization of 4-(p-isopropylphenyl)-2-nonyl-1,3-dioxolane 1 using 2,4,6-triphenylpyrylium tetrafluoroborate (TPT) as sensitizer has been studied to explore the possibility of achieving a slow sunlight-controlled release of polymer-bound carbonyl functionalized semiochemicals. This reaction has been found to produce mainly n-decanal and p-isopropylbenzaldehyde, together with lower amounts of the corresponding acids. The degree of conversion and the product distribution depended on the presence of water or oxygen and the amount of photosensitizer. The results are justified through generation of the radical cation 1+., followed by ring opening and trapping of the radical/cationic sites by oxygen or water. The delocalized 1,3-radical cations III and the ozonides IV appear to be involved as key intermediates. Formation of n-nonanal as a minor product is explained through cleavage of the C2-nonyl bond of 1+..
- Gavina, Pablo,Lopez Lavernia, Natividad,Mestres, Ramon,Miranda, Miguel A.
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p. 4911 - 4916
(2007/10/03)
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