- From Dimethylamine to Pyrrolidine: The Development of an Improved Nickel Pincer Complex for Cross-Coupling of Nonactivated Secondary Alkyl Halides
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Replacement of a dimethyl amino group of the amidobis(amine) nickel(II) pincer complex (1), [(MeN2N)Ni-Cl], by a pyrrolidino group resulted in a new nickel(II) pincer complex (2), [(PyrNMeNN)Ni-Cl]. Complex 2 is an efficient catalyst for Kumada and Suzuki-Miyaura cross-coupling of nonactivated secondary alkyl halides, while complex 1 is largely inactive. The significant activity difference is tentatively attributed to a minimal structural difference, which leads to a more hemilabile ligand.
- Perez Garcia, Pablo M.,Di Franco, Thomas,Epenoy, Alexandre,Scopelliti, Rosario,Hu, Xile
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p. 258 - 261
(2016/01/12)
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- IONIC ALKYLATION OF TERTIARY ALKYL HALIDES WITH TETRAALKYLSILANES
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In the reaction of tertiary alkyl halides with tetraethyl-, tetrapropyl-, tetrabutyl-, and tetraamylsilane in the presence of AlX3 the halogen atom is substituted by the alkyl group with the formation of the corresponding saturated hydrocarbons containing a quaternary carbon atom.As a result of the hydride mobility of the β-hydrogen atom in the tetraalkylsilane ionic hydrogenolysis of the substrate occurs in addition to alkylation, and the degree of hydrogenolysis depends on the alkyl substituent in the silane.
- Bolestova, G. I.,Parnes, Z. N.
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- Lewis Acid Mediated Reactions of Organocopper Reagents. Entrainment in the Conjugate Addition to α,β-Unsaturated Ketones, Esters, and Acids via the RCu*BF3 System
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Lewis acid mediated reactions of organocopper reagents with various kinds of α,β-unsaturated carbonyl derivatives are described.RCu*BF3, as well as RCu-other Lewis acid systems, is useful for the conjugate addition to the α,β-unsaturated ketones and esters, whose double bonds are sterically crowded.Certain α,β-unsaturated carboxylic acids also undergo a 1,4-addition through this reagent.Methyl sorbate undergos a 1,4-addition via BuCu*BF3, while undergoing a 1,6-α,δ-addition via Bu2CuLi.BuCu*BF3 reacts more readily with an aldehyde than with a ketone; the degree of chemoselectivity is greater than that of Bu2CuLi, BuLi, or BuMgBr.The R2CuLi-BF3 system is useful for the double alkylation of α,β-unsaturated esters at the β-position and the carbonyl center.Stereochemical aspects of these new copper reagents are also reported.
- Yamamoto, Yoshinori,Yamamoto, Sinichi,Yatagai, Hidetaka,Ishihara, Yuji,Maruyama, Kazuhiro
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p. 119 - 126
(2007/10/02)
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