Dimethylformamide alkyl group transfer

A number of electrophilic substitutions involving transfer of an alkyl group from mercury to mercury, thallium to mercury, mercury to thallium, and thallium to thallium have been reported by Hart and Ingold14 to proceed through mechanism SE1 in solvent dimethylformamide. It has since been shown by Jensen and Heyman15 that this report is not correct. 

Methylation of purines (and related systems) bearing NH, OH, or SH groups with AW-dimethylformamide dimethylacetal gives the corresponding N-, 0-, and 5-methyl derivatives. With purine itself, 45% of the 7-methyl- and 30% of the 9-methyl-derivative is formed. Alkylation of un-ionized adenine results mainly in alkylation at N-3, whereas alkylation of the anion yields predominantly A -9-substituted adenineMethylation of adenine under phase-transfer conditions gives a nearly quantitative yield of 9-methyladenine. Alkylation of A(-substituted adenines occurs preferentially at N-1, but acylation of the amino-group causes alkylation to occur at N-7. ... 

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