Historically, single-metal organometallic species such as organolithium compounds have been the reagents of choice in synthetic organic chemistry for performing deprotonation reactions. Over the past few years, a complementary new class of metalating agents has started to emerge. Owing to a variable central metal (magnesium, zinc, or aluminum), variable ligands (both in their nature and number), and a variable second metallic center (an alkali metal such as lithium or sodium), "ate" complexes are highly versatile bases that exhibit a synergic chemistry which cannot be replicated by the homometallic magnesium, zinc, or aluminum compounds on their own. Deprotonation accomplished by using these organometallic ate complexes has opened up new perspectives in organic chemistry with unprecedented reactivities and sometimes unusual and unpredictable regioselectivities.

Deprotonative metalation using ate compounds: synergy, synthesis, and structure building

(1980). Reverse Turns in Peptides and Protein. Critical Reviews in Biochemistry: Vol. 8, No. 4, pp. 315-399.

Reverse turns in peptides and proteins.

The article discusses the mechanisms and the applications in organic synthesis, materials, supramolecular, and polymer synthesis of most organic reactions mediated by single electron transfer. Each reaction or class of reactions will be discussed by starting with the original discovery publication, followed by a summary of all or most review articles published in the field, and a discussion of the mechanism(s) and of the most important methodologic and synthetic developments since the most recent review was published. The mechanisms of most organic reactions are considered to proceed by two-electron transfer pathways, even though both biology and radical chemistry rely extensively on one-electron transfer processes. Radicals generated by homolytic cleavage at high temperature were traditionally employed in the industrial production of polymers and to a lesser extent in the synthesis of organic molecules.

Single electron transfer in radical ion and radical-mediated organic, materials and polymer synthesis.

The primary alcohols 1a−e and ethers 4a−d were effectively reduced to the corresponding hydrocarbons 2 by HSiEt3 in the presence of catalytic amounts of B(C6F5)3. To the best of our knowledge, this is the first example of catalytic use of Lewis acid in the reduction of alcohols and ethers with hydrosilanes. The secondary alkyl ethers 4j,k enabled cleavage and/or reduction under similar reaction conditions to produce either the silyl ethers 3m−n or the corresponding alcohol 5a upon subsequent deprotection with TBAF. It was found that the secondary alcohols 1g−i and tertiary alcohol 1j, as well as the tertiary alkyl ether 4l, did not react with HSiEt3/(B(C6F5)3 reducing reagent at all. The following relative reactivity order of substrates was found:  primary ≫ secondary > tertiary. A plausible mechanism for this nontraditional Lewis acid catalyzed reaction is proposed.

A Novel B(C6F5)3-Catalyzed Reduction of Alcohols and Cleavage of Aryl and Alkyl Ethers with Hydrosilanes†

Halogen-magnesium exchange of various aryl halides is achieved with a magnesium ate complex at low temperatures. Tributylmagnesate (nBu3MgLi) induces facile iodine-magnesium exchange at -78 degrees C. Dibutylisopropylmagnesate (iPr(n)Bu2MgLi) is more reactive than nBu3MgLi, and this reagent accomplishes selective bromine-magnesium exchange at -78 degrees C. This procedure is utilized for the preparation of various polyfunctionalized arylmagnesium species. The exchange of alkenyl halides using this method proceeds with retention of configuration of the double bond.

Selective halogen-magnesium exchange reaction via organomagnesium ate complex

Mechanisms of Grignard reagent addition to ketones

Stereoselective organometallic alkylation reactions. III. Ate complex addition to cyclic and bicyclic ketones

Mechanisms of organometallic alkylation reactions. II. Kinetics of trimethylaluminum addition to benzophenone inn benzene. An example of a change in mechanism with stoichiometry

Stereoselective organometallic alkylation reactions. II. Organomagnesium and organoaluminum addition to ketones having varied steric requirements. New concept of stereochemical control

J. Laemmle

Papers

Mechanisms of Grignard reagent addition to ketones

Stereoselective organometallic alkylation reactions. III. Ate complex addition to cyclic and bicyclic ketones

Mechanisms of organometallic alkylation reactions. II. Kinetics of trimethylaluminum addition to benzophenone inn benzene. An example of a change in mechanism with stoichiometry

Stereoselective organometallic alkylation reactions. II. Organomagnesium and organoaluminum addition to ketones having varied steric requirements. New concept of stereochemical control

Organometallic reaction mechanisms. VIII. Detailed description of the mechanism of methylmagnesium bromide addition to 2-methylbenzophenone