- Zinc(ii)-catalyzed Grignard additions to ketones with RMgBr and RMgI
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Highly efficient alkylations and arylations of ketones with Grignard reagents (RMgBr and RMgI) have been developed using catalytic ZnCl2, Me3SiCH2MgCl, and LiCl. Tertiary alcohols were obtained in high yields with high chemoselectivities, while minimizing undesired side products produced by reduction and enolization.
- Hatano, Manabu,Ito, Orie,Suzuki, Shinji,Ishihara, Kazuaki
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scheme or table
p. 2674 - 2676
(2010/07/08)
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- Highly efficient alkylation to ketones and aldimines with Grignard reagents catalyzed by zinc(II) chloride
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A highly efficient alkylation to ketones and aldimines with Grignard reagents in the presence of catalytic trialkylzinc(II) ate complexes derived from ZnCl2 (10 mol %) in situ was developed. This simple Zn(II)-catalyzed alkylation could minimize the well-known but serious problems with the use of only Grignard reagents, which leads to reduction and aldol side products, and the yield of desired alkylation products could be improved. Copyright
- Hatano, Manabu,Suzuki, Shinji,Ishihara, Kazuaki
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p. 9998 - 9999
(2007/10/03)
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- Highly alkyl-selective addition to ketones with magnesium ate complexes derived from Gignard reagents
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(Chemical Equation Presented) A highly efficient alkyl-selective addition to ketones with magnesium ate complexes derived from Grignard reagents and alkyllithiums is described. The nucleophilicity of R in R3MgLi is remarkably increased compared to that of the original RLi or RMgX, while the basicity of R3MgLi is decreased. Furthermore, a highly R-selective addition to ketones is demonstrated using RMe2MgLi in place of R 3MgLi.
- Hatano, Manabu,Matsumura, Tokihiko,Ishihara, Kazuaki
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p. 573 - 576
(2007/10/03)
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- Reactions of Et3ZnLi with ketones: Electronic and steric effects
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Toluene solutions of composition Et3ZnLi react rapidly with aldehydes and ketones to form addition products. Et3ZnNa and Et3ZnK solutions react readily with the same substrates although metalation, as well as addition, is significant with substrates having α-hydrogens. The Et3ZnM solutions react with 2-cyclohexenone to give mainly the 1,4-addition product. Relative rates of addition of Et3ZnLi to substituted acetophenones give a Hammett ρ of 2.78. Addition of Et3ZnLi to acetophenone is slowed significantly by α and ortho methyl substituents; relative rates of addition to acetophenone, o-methylacetophenone, and tert-butyl phenyl ketone are 1.00, 0.012, and 0.003.
- Musser,Richey Jr.
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p. 7750 - 7756
(2007/10/03)
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- Direct Transformation of Trialkyl Phosphates into Organolithium Compounds by a DTBB-Catalysed Lithiation
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The reaction of different alkylic or phenylic phosphates 1 with an excess of lithium powder and a catalytic amount of DTBB (5 mol percent) in the presence of an electrophile -Barbier-type reaction conditions- in THF at -30 deg C leads to the formation of the expected products 2, resulting from the reaction of the in situ generated organolithium compound with the corresponding electrophile.
- Guijarro, David,Mancheno, Balbino,Yus, Miguel
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p. 8551 - 8558
(2007/10/02)
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