- Facile Synthesis of Polysubstituted 2-Pyrones via TfOH-Mediated Ring Expansion of 2-Acylcyclopropane-1-carboxylates
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A facile route to polysubstituted 2-pyrones from readily available 2-acylcyclopropane-1-aryl-1-carboxylates mediated by TfOH is reported. The strongly donating 1-aryl group is important for directing the C-C bond cleavage of the donor-acceptor cyclopropane ring, which then leads to the formation of the 2-pyrone ring through lactonization.
- Shao, Jiru,An, Caiyun,Wang, Sunewang R.
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p. 4030 - 4041
(2021/07/19)
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- Enzyme-catalyzed domino reaction: Efficient construction of spirocyclic oxindole skeleton using porcine pepsin
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Pepsin from porcine gastric mucosa was used as a sustainable and environmentally friendly biocatalyst in the domino Knoevenagel/Michael/Michael reaction for the synthesis of spirooxindole derivatives in methanol. A wide range of isatins and α,β-unsaturated ketones reacting with malononitrile provided the corresponding products in yields of up to 99% with diastereoselectivities of up to >99:1 dr. This pepsin-catalyzed domino reaction provided a novel case of enzyme catalytic promiscuity.
- He, Yan-Hong,He, Tao,Guo, Jun-Tao,Li, Rui,Xiang, Yang,Yang, Da-Cheng,Guan, Zhi
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p. 2239 - 2248
(2016/04/26)
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- Sequential aldol Condensation-Transition metal-Catalyzed addition reactions of aldehydes, methyl ketones, and arylboronic acids
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Sequential aldol condensation of aldehydes with methyl ketones followed by transition metal-catalyzed addition reactions of arylboronic acids to form β-substituted ketones is described. By using the 1,1′;-spirobiindane- 7,7′;-diol (SPINOL)-based phosphite, an asymmetric version of this type of sequential reaction, with up to 92% ee, was also realized. Our study provided an efficient method to access β-substituted ketones and might lead to the development of other sequential/tandem reactions with transition metal-catalyzed addition reactions as the key step.
- Liao, Yuan-Xi,Xing, Chun-Hui,Israel, Matthew,Hu, Qiao-Sheng
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supporting information; experimental part
p. 2058 - 2061
(2011/06/19)
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- Reaction behavior of cyclopropylmethyl cations derived 1-phenylselenocyclopropylmethanols with acids
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The 1-phenylselenocyclopropylmethyl cations are generated by the reaction of the corresponding cyclopropylmethanols 1 with TsOH. The reaction in methanol proceeds to afford the homoallylic ethers 2, ring-enlargement products 3, 4, and ring opening product
- Honda, Mitsunori,Nishizawa, Toshiaki,Nishii, Yuko,Fujinami, Shuhei,Segi, Masahito
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experimental part
p. 9403 - 9411
(2009/12/28)
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- Process for separating zinc salts from zinc alcoholates or zinc amides containing non-aqueous synthesis solvents
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A process for the removal of zinc from organic solutions containing zinc alcoholates or zinc amides comprises addition of an alkylating, arylating, acylating or silylating agent in the presence of a precipitating agent having at least two nitrogen donors followed by separation of the precipitated solid.
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Page/Page column 9-12
(2010/02/06)
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- A Convenient and Efficient Unsymmetrical Ketone Synthesis from Acid Chlorides and Alkyl Iodides Catalyzed by Palladium
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Unsymmetrical ketones are prepared in good or excellent yields by a palladium catalyzed coupling reaction of acid chlorides and alkyl iodides meditated by Zn-Cu couple.
- Tamaru, Yoshinao,Ochiai, Hirofumi,Sanda, Fumio,Yoshida, Zen-ichi
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p. 5529 - 5532
(2007/10/02)
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- ALDOL CONDENSATIONS WITH METAL(II) COMPLEX CATALYSTS.
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Aldol condensations of aldehydes with ketones catalyzed by the first-row transition metal(II) complexes have been widely studied. Complexes of Co(II), Ni(II), Cu(II), and Zn(II) acetates with 2,2 prime -bypyridine were effective catalysts to afford cross-aldol condensation products, alpha , beta ,-unsaturated ketones, in high yields without any self-condensation products. The reaction of 2-butanone, unsymmetrical aliphatic ketone, with benzaldehyde took place regioselectively to give base-catalyzed-type products.
- Irie,Watanabe
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p. 1366 - 1371
(2007/10/02)
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