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An ate complex in chemistry is a salt formed by reaction of a Lewis acid with a base whereby the central atom increases itsvalence . (Note that in this definition the meaning of valence is equivalent to coordination number) Often in chemical nomenclature the phrase ate is suffixed to the element in question. For example, the ate complex of a boron compound is called a borate. Thus trimethylborane and methyllithium react to form the ate compound Me4B-Li+. This concept was introduced by Georg Wittig in 1958 The term is usually reserved for the metals of metals in groups 2, 11 and 12. Similarly, Lewis bases form onium salts
The reaction of an organolithium or an organomagnesium species with an electrophile is a cornerstone of organic synthesis and features in many commercial and development scale manufacturing processes.
Process chemists at Merck have reported* notable improvements in the robustness and scalability of such a reaction, by balancing the high reactivity of the organolithium with the stability of the analogous organomagnesium species via a magnesium "ate" intermediate:
The equivalent organolithium reaction (nBuLi, toluene, -78oC) requires cryogenic conditions and very tight control of stereochemistry. The corresponding Grignard reactions by the Knochel and Queguiner methodologies (iPrMgCl or iPr²Mg, THF, 25oC) give lower yields, are very sluggish and give side products. In contrast, the "ate" approach shown above can tolerate reasonable deviations in stoichiometry and temperature, and it scales up well.
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