Methylation sometimes involve use of nucleophilic methyl reagents.  Strongly nucleophilic methylating agents include methyllithium () or Grignard reagents such as methylmagnesium bromide (). For example,  will add methyl groups to the carbonyl (C=O) of ketones and aldehyde.:
Milder methylating agents include tetramethyltin, dimethylzinc, and trimethylaluminium.