Ate complex


Vatican City Courtyard in Rome  DRAG YOUR CURSOR FOR PANAROMIC VIEW






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

Improving the robustness and scalability of of organolithium and Grignard reactions 

DO THE REACTION AT MINUS 10 DEG CENTIGRADE

magnesium "ate" approach was originally described by Oshima et al (Angew. Chem. Int. Ed. Engl., 2000, 39, 2481


'ATE' IS PREPD AS FOLLOWS--N-BUMGCL-0.35M AND N-BULI-0.75 MOLES gives N-BU3MG+LI-

N-BU3MG+LI- reacts with Br GP in presence of DMF to give -CHO GP ----THIS WAS PRESENTED IN 
R.P.Volante (Merck, USA), "Process Development for a Novel Muscarinic M3 Receptor Antagonist", Presentation given at Chiral USA 2003, Chicago, 21/22 October 2003.


 

Improving the robustness and scalability of of organolithium and Grignard reactions

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.


[PPT] 

2009/Beall.ppt - Target Directed Synthesis via StReCH Chemistry ...

File Format: Microsoft Powerpoint - View as HTML
configurational and chemical stability of carbenoid during ate-complex formation. carbenoid... stereospecific formation and break-down of ate-complex ...
oregonstate.edu/dept/biochem/hhmi/undergradresearch/2009/Beall.ppt
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