- Copper(i) pyrimidine-2-thiolate cluster-based polymers as bifunctional visible-light-photocatalysts for chemoselective transfer hydrogenation of α,β-unsaturated carbonyls
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The photoinduced chemoselective transfer hydrogenation of unsaturated carbonyls to allylic alcohols has been accomplished using cluster-based MOFs as bifunctional visible photocatalysts. Assemblies of hexanuclear clusters [Cu6(dmpymt)6] (1, Hdmpymt = 4,6-dimethylpyrimidine-2-thione) as metalloligands with CuI or (Ph3P)CuI yielded cluster-based metal organic frameworks (MOFs) {[Cu6(dmpymt)6]2[Cu2(μ-I)2]4(CuI)2}n (2), {[Cu6(dmpymt)6]2[Cu2(μ-I)2]4}n (3), respectively. Nanoparticles (NPs) of 2 and 3 served both as photosensitizers and photocatalysts for the highly chemoselective reduction of unsaturated carbonyl compounds to unsaturated alcohols with high catalytic activity under blue LED irradiation. The photocatalytic system could be reused for several cycles without any obvious loss of efficiency.
- Zhang, Meng Juan,Young, David James,Ma, Ji Long,Shao, Guo Quan
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p. 14899 - 14904
(2021/05/19)
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- Tuning the Product Selectivity of the α-Alkylation of Ketones with Primary Alcohols using Oxidized Titanium Nitride Photocatalysts and Visible Light
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The direct α-alkylation of ketones with alcohol to synthesize important α-alkylated ketones and enones is an attractive procedure for C-C bond formation. High reaction temperatures are always needed for heterogeneous catalysis using non-noble metals, and switching product selectivity in one catalysis system remains a great challenge. In the present study, a visible-light-driven procedure for this reaction is proposed, using oxidized TiN photocatalysts under mild conditions, whereby the product selectivity can be well-tuned. Oxidized TiN photocatalysts with tunable surface N/O ratios were successfully synthesized through the facile and flexible thermal oxidation treatment of low-cost TiN nanopowder. The α-alkylation of acetophenone with benzyl alcohol to form the two important compounds chalcone and dihydrochalcone occurred even at room temperature and almost complete conversion was achieved at 100 °C under visible light. The proportion of the two products can be well-tuned by switching the surface N/O ratio of the synthesized photocatalysts. Visible light is demonstrated to affect the surface N/O ratio of the photocatalysts and contribute to tuning the product selectivity. Light intensity and action spectrum study proves that the generation of energetic charge carriers results in the observed activities under visible light, based on interband transitions of TiN or the ligand-to-metal charge transfer (LMCT) effect of the surface complex formed on TiO2. Thermal energy can be coupled with light energy within this photocatalytic system, which will facilitate the full use of solar energy. Different sequential reaction mechanisms on TiN and TiO2 are proposed to be responsible for the tunable product selectivity. The wide reaction scope, the fine conversion at a low light intensity, and the favorable reusability of photocatalysts prove the great application potential of this visible-light-driven procedure for the α-alkylation of ketones with primary alcohols.
- Li, Peifeng,Su, Haijia,Xiao, Gang,Zhao, Yilin
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p. 3640 - 3649
(2020/04/09)
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- Lithium amidoborane, a highly chemoselective reagent for the reduction of α,β-unsaturated ketones to allylic alcohols
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Lithium amidoborane (LiNH2BH3, LiAB for short), is capable of chemoselectively reducing α,β-unsaturated ketones to the corresponding allylic alcohols at ambient temperature. A mechanistic study shows that the reduction is via a double hydrogen transfer process. The protic H(N) and hydridic H(B) in amidoborane add to the O and C sites of the carbonyl group, respectively.
- Xu, Weiliang,Zhou, Yonggui,Wang, Ruimin,Wu, Guotao,Chen, Ping
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experimental part
p. 367 - 371
(2012/01/13)
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- Oxidation of Alcohols with Dimethyl Selenide -N-Chlorosuccinimide Complex
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Dimethyl selenide reacts with N-chlorosuccinimide (NCS) to give a new complex, with which various alcohols are successfully oxidized to carbonyl compounds.Notably, this method is applicable to allylic alcohols without formation of allylic chlorides and rearranged products. β-Hydroxy selenide 8 is converted to β-oxo selenide 9 by treatment with NCS.On the other hand, facile deselenization occurs in the case of γ-hydroxy selenide 10 under similar conditions.A plausible mechanism of the reactions is also discussed.
- Takaki, Ken,Yasumura, Masateru,Negoro, Kenji
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- STEREOCHEMICAL INVESTIGATIONS. XXVII. CONFORMATIONAL EFFECT OF THE PREDOMINANCE OF THE AXIAL CONFORMER IN 2-SUBSTITUTED BENZYLIDENECYCLOHEXANES
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The conformational equilibrium in the compounds was investigated by dynamic PMR spectroscopy, and the effect of the polarity of the solvent was studied.A comparative analysis was made of the conformational behavior of the 2-substituted benzylidenecyclohex
- Zefirov, N. S.,Baranenkov, I. V.
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p. 2112 - 2118
(2007/10/02)
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