β‐Silyl Diorganozinc Compounds—A New Class of Useful Zinc Reagents

Berger, Stefan; Langer, Falk; Lutz, Christian; Knöchel, Paul; Mobley, T. Andrew; Reddy, Ch. Kishan

doi:10.1002/anie.199714961

“…This intermediate, which is thought to have the dimeric structure (EtZnOH) 2 , is very unstable and reacts further to give polymers of the form Et(ZnO) n (equation 19). Some of these products exhibit a good catalytic activity for the polymerization of lactones and cyclic ethers.…”

Section: 131mentioning

confidence: 97%

Zinc: Organometallic ChemistryBased in part on the article Zinc: Organometallic Chemistry by Gerard Parkin which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Gr��vy¹

2005

Encyclopedia of Inorganic Chemistry

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Since the discovery of the first organozinc compounds by Sir Edward Frankland in 1849, the organometallic chemistry of zinc made remarkable advances and organozinc species have become essential tools for organic chemists. During the past decade, numerous new and modified procedures for the preparation of the title compounds have been published, rendering their synthesis easier, faster, and less expensive and giving higher yields. The coordination chemistry of organozinc derivatives has been subject of further interest and various intra‐ and intermolecular complexes with different donor ligands have been structurally characterized by X‐ray crystallography and spectroscopic methods. The accumulation of molecular structures, physicochemical studies, and computational calculations has led to a better understanding of the organozinc chemistry, and consequently to the design of new derivatives for specific applications. Even if the development of areas like the chemistry of organozinc anions and cations is still in its early stage, these compounds, which exhibit properties different than those of the parent organometallic species, appear to have promising applications in synthesis and catalytic reactions. During the past ten years, the chemistry of organo‐ gem ‐dizincio derivatives has also been the subject of much interest and progress. These reagents can form two carbon–carbon bonds in a one‐pot reaction and with high stereoselectivity. They became key reagents for organic chemists who want to combine multiple transformations in one operation. The importance of organometallic compounds of zinc can be seen in the growing number of their applications in synthesis. They are used in many reactions such as substitutions, additions to carbonyl compounds and unsaturated systems, cyclopropanations, and polymerizations. Furthermore, as a result of their low reactivity, they tolerate a wide variety of functionalities and perform most of the transformations with high regio‐ and enantioselectivity. After spending more than half a century in the shade of Grignard and organolithium reagents, organozinc reagents are becoming more and more important in modern chemistry.

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“…This reaction takes place only between dialkylzincs and alkyl iodides; however, in comparison with the few other methods described for the preparation of mixed diorganozincs, this procedure represents a fantastic enhancement for alkyl group exchange (R-Zn-R ). 19 …”

Section: Iodine -Zinc Exchangementioning

confidence: 99%

“…Nevertheless, cryoscopic studies carried out on the controlled hydrolysis of diethylzinc show the formation of organozinc hydroxide EtZnOH as intermediate. 130,131 This intermediate, which is thought to have the dimeric structure (EtZnOH) 2 , is very unstable and reacts further to give polymers of the form Et(ZnO) n (equation 19). Some of these products exhibit a good catalytic activity for the polymerization of lactones and cyclic ethers.…”

Section: Other Organozinc Compounds Containing Oxygenmentioning

confidence: 99%

Zinc: Organometallic ChemistryBased in part on the article Zinc: Organometallic Chemistry by Gerard Parkin which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Grévy

¹

2005

Encyclopedia of Inorganic and Bioinorganic Chemistry

View full text Add to dashboard Cite

Since the discovery of the first organozinc compounds by Sir Edward Frankland in 1849, the organometallic chemistry of zinc made remarkable advances and organozinc species have become essential tools for organic chemists. During the past decade, numerous new and modified procedures for the preparation of the title compounds have been published, rendering their synthesis easier, faster, and less expensive and giving higher yields. The coordination chemistry of organozinc derivatives has been subject of further interest and various intra‐ and intermolecular complexes with different donor ligands have been structurally characterized by X‐ray crystallography and spectroscopic methods. The accumulation of molecular structures, physicochemical studies, and computational calculations has led to a better understanding of the organozinc chemistry, and consequently to the design of new derivatives for specific applications. Even if the development of areas like the chemistry of organozinc anions and cations is still in its early stage, these compounds, which exhibit properties different than those of the parent organometallic species, appear to have promising applications in synthesis and catalytic reactions. During the past ten years, the chemistry of organo‐ gem ‐dizincio derivatives has also been the subject of much interest and progress. These reagents can form two carbon–carbon bonds in a one‐pot reaction and with high stereoselectivity. They became key reagents for organic chemists who want to combine multiple transformations in one operation. The importance of organometallic compounds of zinc can be seen in the growing number of their applications in synthesis. They are used in many reactions such as substitutions, additions to carbonyl compounds and unsaturated systems, cyclopropanations, and polymerizations. Furthermore, as a result of their low reactivity, they tolerate a wide variety of functionalities and perform most of the transformations with high regio‐ and enantioselectivity. After spending more than half a century in the shade of Grignard and organolithium reagents, organozinc reagents are becoming more and more important in modern chemistry.

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“…Knochel found that trimethylsilylmethyl, Me 3 SiCH 2 group [19], and also neopentyl, t-BuCH 2 and neophyl PhMe 2 CCH 2 groups [20], act as excellent residual groups. Mixed diorganozincs of the type R R R T Zn and R R (FG-R T )Zn have been used advantageously for the enantioselective addition to aldehydes [19][20][21] and to imines [22], for the addition to various Michael acceptors [23][24][25][26] and for the Ni catalyzed substitution with prim-alkyl halides [27] and CuCN mediated substitution with allylic phosphates [28].…”

Section: Introductionmentioning

confidence: 99%