557-20-0Relevant articles and documents
ZINC ENOLATES: C- OR O-METALLATION?
Dekker, Jan,Schouten, Abraham,Budzelaar, Peter H. M.,Boersma, Jaap,Van Der Kerk, Gerrit J. M.,et al.
, p. 1 - 12 (1987)
Two methods have been used for the generation of zinc enolates: the reaction of EtZnOMe with enol acetates, and that of lithium enolates with zinc chloride.Most of the zinc compounds prepared proved to be very reactive towards carbonyl functions, and so they cannot be isolated from the EtZnOMe/enol acetate system.The final products of these reactions are polymerisation and self-condensation products and β-diketonates, the latter being formed by condensation reactions of the zinc enolates with an acetate molecule.The structure of 2 HPac=pivaloylacetone, (CH3)3CCOCH2COCH3), isolated in 20percent yield from the reaction of EtZnOMe with CH3COOC(t-Bu)=CH2, was determined by X-ray diffraction analysis.The compound forms monoclinic crystals, space group P21/c, with two dimers in a cell of dimensions a 11.677(4), b 18.299(9) and c 12.719(5) Angstroem and β 117.26(3) deg.The structure closely resembles that of the known complex 2.The complications involving reactions of zinc enolates with enol acetates were avoided by treating lithium enolates with zinc chloride.Polimeryzation and self-condensation could be prevented by using the very bulky enolate LiOC(t-Bu)=CMe2.In this way, the corresponding stable zinc enolate RZnCl*THF was obtained as a dissociating dimer.No replacement of the second chlorine atom by an enolate group occurred even when a large excess of lithium enolate was used.The reactivity of the zinc enolates suggest that they contain both zinc-carbon and zinc-oxygen bonds.They are assumed to have a cyclic structure which resembles that of the Reformatsky reagent.
ULTRASONIC IRRADIATION IN ONE-POT SYNTHESIS OF TRIETHYLALUMINUM ETHERATE AND ITS CONVERSION INTO OTHER ORGANOMETALLIC COMPOUNDS
Lin, Yih-tsung
, p. 277 - 284 (1986)
A mixture of ethyl bromide, aluminum and magnesium powders was irradiated with ultrasound and ethylaluminum sesquibromide(I) formed at room temperature.As soon as diethyl ether was introduced into the reaction medium, ethylmagnesium bromide(II) was formed in situ and subsequently treated with I to give the etherate of triethylaluminum (III, TEA * OEt2) in satisfactory yield (82percent) and purity (98percent).III, thus obtained, could react with triethyl borate or zinc chloride to give triethylborane (90percent) and diethylzinc (82percent) respectively.
Dinuclear Zinc-AzePhenol Catalyzed Asymmetric Aza-Henry Reaction of N-Boc Imines and Nitroalkanes under Ambient Conditions
Liu, Shanshan,Gao, Wen-Chao,Miao, Yu-Hang,Wang, Min-Can
, p. 2652 - 2659 (2019/02/26)
The asymmetric aza-Henry reaction of N-Boc imines and nitroalkanes was realized in the presence of 10 mol % dinuclear zinc-AzePhenol catalysts under ambient conditions. A variety of nitroamines were obtained in good yields (up to 97%) with excellent enantioselectivities (up to 99% ee) and high diasteroselectivity (up to 14:1 dr). Our protocol combined the operational simplicity and mild reaction conditions, thus making the process amenable for technical applications.
Iron-catalyzed chain growth of ethylene: In situ regeneration of ZnEt2 by tandem catalysis
Cariou, Renan,Shabaker, John W.
, p. 4363 - 4367 (2015/11/11)
A dual catalyst system to implement in situ regeneration of ZnEt2, the Chain Transfer Agent (CTA) in Catalyzed Chain Growth of ethylene (CCG), has been demonstrated. As in typical CCG systems, an Fe homogeneous catalyst is used to grow oligomeric chains that transfer rapidly to ZnEt2. However, rather than liberating alkane products and destroying the expensive chain transfer agent via acid hydrolysis workup, a second Fe-alkyl catalyst, (BiPy)2FeEt2, has been introduced to regenerate ZnEt2 via ethyl/alkyl exchange and liberate the oligomer chains as α-olefins via ss-hydride elimination. This improvement reduces the ZnEt2 loading and leaves the chain growth catalyst competent, in contrast to Ni(acac)2 shown to be unsuitable for in situ tandem catalysis. These findings greatly enhance the industrial viability of the chemistry.