- Grubbs Metathesis Enabled by a Light-Driven gem-Hydrogenation of Internal Alkynes
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[(NHC)(cymene)RuCl2] (NHC=N-heterocyclic carbene) complexes instigate a light-driven gem-hydrogenation of internal alkynes with concomitant formation of discrete Grubbs-type ruthenium carbene species. This unorthodox reactivity mode is harnessed in the form of a “hydrogenative metathesis” reaction, which converts an enyne substrate into a cyclic alkene. The intervention of ruthenium carbenes formed in the actual gem-hydrogenation step was proven by the isolation and crystallographic characterization of a rather unusual representative of this series carrying an unconfined alkyl group on a disubstituted carbene center.
- Biberger, Tobias,Fürstner, Alois,Zachmann, Raphael J.
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supporting information
p. 18423 - 18429
(2020/08/25)
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- Regio- and enantioselective Baeyer-Villiger oxidation: Kinetic resolution of racemic 2-substituted cyclopentanones
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A kinetic resolution of racemic 2-substituted cyclopentanones via highly regio- and enantioselective Baeyer-Villiger oxidation has been successfully developed. The reaction could afford the normal 6-substituted δ-lactones in up to 98% ee and >19/1 regioselectivity. Meanwhile, the unreacted ketones were recovered in excellent ee values (up to 98%). It represents the best results of the kinetic resolution of racemic 2-substituted cyclopentanones via nonenzymic asymmetric BV oxidation.
- Zhou, Lin,Liu, Xiaohua,Ji, Jie,Zhang, Yuheng,Wu, Wangbin,Liu, Yangbin,Lin, Lili,Feng, Xiaoming
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p. 3938 - 3941
(2014/08/18)
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- Alder-ene reaction of aryne with olefins
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A novel intermolecular Alder-ene reaction based on aryne and olefins was developed. We performed this transformation under mild conditions such as at room temperature, and this reaction displayed high selectivity and good yields only in the presence of CsF. Hence, the intermolecular Alder-ene reaction of aryne with olefins provides an effective route to synthesize derivatives of olefins.
- Chen, Zhao,Liang, Jinhua,Yin, Jun,Yu, Guang-Ao,Liu, Sheng Hua
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supporting information
p. 5785 - 5787
(2013/10/01)
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- Stereoselective synthesis of δ-lactones from 5-oxoalkanals via one-pot sequential acetalization, tishchenko reaction, and lactonization by cooperative catalysis of samarium ion and mercaptan
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By the synergistic catalysis of samarium ion and mercaptan, a series of 5-oxoalkanals was converted to (substituted) δ-lactones in efficient and stereoselective manners. This one-pot procedure comprises a sequence of acetalization, Tishchenko reaction and lactonization. The deliberative use of mercaptan, by comparison with alcohol, is advantageous to facilitate the catalytic cycle. The reaction mechanism and stereochemistry are proposed and supported by some experimental evidence. Such samarium ion/mercaptan cocatalyzed reactions show the feature of remote control, which is applicable to the asymmetric synthesis of optically active δ-lactones. This study also demonstrates the synthesis of two insect pheromones, (2S,5R)-2-methylhexanolide and (R)-hexadecanolide, as examples of a new protocol for asymmetric reduction of long-chain aliphatic ketones.
- Hsu,Fang
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p. 8573 - 8584
(2007/10/03)
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- Ruthenium complex-catalyzed novel transformation of alkyl formates
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The following ruthenium-catalyzed novel transformations of alkyl formates have been developed: (1) selective decarbonylation of alkyl formates to the corresponding alcohols; (2) alkylation of arenes and alkenes using alkyl formates as an alkylating reagent via decarboxylation.Also the ruthenium-catalyzed addition of alcohols to alkenes has been developed as an appendant reaction, providing an effective method for the protection of alcohols.Keywords: Ruthenium; Catalysis; Alkyl; Arene; Alkene; Alcohol
- Kondo, Teruyuki,Kajiya, Satoshi,Tantayanon, Supawan,Watanabe, Yoshihisa
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- Stereoselective Epoxidation of 3-trans-Benzylideneisoborneol
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2-Benzylidenecyclopentanol (2) can be epoxidized stereoselectively to furnish 2-trans-benzylidene-1β-hydroxycylopentane β-oxide (4) with either t-butyl hydroperoxide in the presence of vanadium catalyst or m-chloroperoxybenzoic acid.Epoxidation of 3-trans
- Sanghvi, Y. S.,Rao, A. S.
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p. 317 - 320
(2007/10/02)
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- Synthesis of Olefins from α-Chlorocarbonyl Compounds
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Olefins or diolefins with the double bonds in predetermined positions are obtained in moderate to good yields by treatment of α-chlorocarbonyl compounds with Grignard reagents and lithium in a single process.
- Barluenga, Jose,Yus, Miguel,Concellon, Jose M.,Bernad, Pablo
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p. 677 - 692
(2007/10/02)
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