Trace Amounts of Second Metal Elements Can Play a Key Role in the Generation of Organometallic Compounds

Abstract

). He has developed several synthetic methods using early transition metals such as chromium, titanium, and tantalum. Current research in his group is aimed towards the use of the complexes of group 7 metals as catalysts in organic synthesis and C-H activation initiated by insertion of transition metals into heteroatom-hydrogen bonds. AbstractDuring the development of new synthetic organic reactions by the use of group 47 metals, we twice encountered a reproducibility problem. The key factor was trace amounts of second metal elements that contaminated the first, main metals, i.e., nickel in chromium and lead in zinc. We had determined the standard procedures for these reactions and they were adopted in Organic Syntheses. The difference in the source of zinc, i.e., contamination by a catalytic amount of lead, proved to affect both the reactivity of the SimmonsSmith reaction and the formation of alkylzinc from the corresponding iodides. By using the concept of catalytic effects of the second metals, we developed a method to use manganese metal and applied this to sequential radical and anionic reactions. In addition, allylic aluminum species were prepared smoothly from allylic halides and aluminum by addition of an indium salt, the second element. In this account, I describe how the synthetic methods were discovered and developed, with an emphasis on the stories behind the communications and articles.

Solvent Effects on Heterogeneous Rate Constants for Indium Mediated Allylations

“…We plan to apply this technique to other reactions. For example, the formation of the zinc carbenoid in the Simmons/Smith reaction is very sensitive to the activation of the solid zinc surface . This effect is little understood, , and visualization of the surface during the reaction offers a powerful strategy to understand the mechanism …”

Catalytic Transformations of Sulfonium Salts via C‐S Bond Activation

“…[50] Very recently, Hintermann reported nickel(diimine)-catalyzed generation of arylzinc reagents from general aryl sulfonates. [51] These catalytic methods, as well as Takai's noted work, [52] promise the further prospect of catalytic zincinsertion reaction.…”

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

“…In these bond formations, organometallics play an essential role because they possess various reactivities depending on the central metal ions that they own. For example, carbon has strong nucleophilicity when bonded to metals with low electronegativity, as demonstrated in the reaction of organolithium, organomagnesium, organozinc, and organochromium A , to facilitate addition reactions of appropriate carbon electrophiles such as aldehydes ( Scheme 1 , top) [ 1 ]. In contrast, π-electrophilic carbon-connected late transition metals B facilitate the carbometalation of carbon–carbon multiple bonds, leading to multi-substituted carbon frameworks ( Scheme 1 , bottom) [ 2 – 3 ].…”