Method D: The Eschweiler-Clarke methylation14 was used adding the diamine slowly to the mixture of formaldehyde and formic acid. Reaction was then completed by refluxing for 3.5 hr. The mixture was acidified with concentrated HCI and the solvent removed under reduced pressure. The residue was recrystallized from ethanol as indicated in the Table to give XXI. Acetylation.-The addition of N, N'-diisopropylethylenediamine to excess acetic anhydride ...