Grignard compounds salts, quaternary

These observations have been interpreted in terms of the hard-soft acid-base theory (77CJC4112), in which the salts of the harder cations, such as the Li+ ion, lead to C-alkylation, whilst the salts of the soft cations, such as the quaternary ammonium salts, are TV-alkylated. This interpretation is particularly relevant in understanding the reactivity of the heteroaryl-magnesium salts. The Mg2+ ion is a harder cation than the Li+ ion and, with the more strongly associated Grignard compounds, C-alkylation predominates. Generally, the pyrrole... 

The reaction of a Grignard reagent with quaternary salts obtained from. V-oxides of pyridine, quinoline, and their homologs has been utilized401,402 for the preparation of 2-alkylated compounds. 

Chloromethyl-5,6-dihydro- 1,3-oxazines react with aryl Grignard reagents, giving ultimately an arylacetic acid.249 Quaternary salts of 5,6-dihydro compounds also furnish carboxylic acids.240... 

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