Organomagnesium compounds, hydrogenation

In earlier studies [f J], it was shown that pentafluorobenzene has an acidic aryl hydrogen capable of metalation by organolithium or organomagnesium compounds to yield perfluorophenylorganometallic compounds... 

Under the conditions used for the reductive cleavage of the O—N bond in isoxazoles, a similar reaction readily occurs with isoxa-zolines, e.g. on treatment with organomagnesium compounds and on catalytic hydrogenation.- Hydrogenolysis of the O—N bond (180 181 182 183) was used to elucidate the structure of isoxa-zolones from -ketoesters. -... 

When the organomagnesium compound possesses tertiary (or several secondary) (3-hydrogen atoms, and the carbonyl compound is sterically hindered, reduction may be the predominant reaction. This mode of reduction may be suppressed to some extent in the presence of metal salts [A, 7],... 

Organomagnesium compounds are kinetically less-reactive bases toward weakly acidic hydrogens than organolithium compounds. Usually, Metalation using an organomagnesium compound is practically limited to acid hydrogens with pXa of about 25 or lower. This includes aUcynes (equation 14) and derivatives of cyclopentadiene, indene, and fluorene. Even... 

From preparation of different classes of organomagnesium compounds by metallation are excluded metallations, often relatively facile, of hydrogens on carbons next to groups such as carbonyl or cyano that produce organomagnesiums in which the metal is associated more with a heteroatom than with carbon. 

Alkenes from organolithium and organomagnesium compounds. This reagent abstracts the )S-hydrogen of organolithium and organomagnesium compounds at low temperatures. Trialkylboranes also have this property, but the reaction is somewhat slower. The yields of alkenes increase within the series primary < secondary < tertiary. Formation of the less stable Hofmann alkene is favored. Examples ... 

Grignard was awarded the Nobel Prize in Chemistry in 1912 for his extensive work with organomagnesium compounds. He returned to the University of Lyons in 1919, where he succeeded Barbier as head of the department and continued his research. Grignard also conducted an extensive research program in the fields of terpenoid natural products, ozonolysis, aldol reactions, and catalytic hydrogenation and dehydrogenation. However, it is for his... 

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