Synthesis of 2-Alkylputrescines from 3-Alkylpyrroles

Article abstract of DOI:10.1021/jo00237a032

Acylation of 2-(trichloroacetyl)pyrrole gave the 4-acyl derivatives (from 4-formyl to 4-hexanoyl) in good yields.Alkaline treatment gave corresponding 4-acyl-2-pyrrolecarboxylic acids, were decarboxylated to the 3-acylpyrroles by prior conversion to the 3-acyl-2,4,5-triiodopyrroles followed by hydrogenolysis.The 3-acylpyrroles were reduced by treatment with hydrazine in alkaline medium to the 3-alkylpyrroles.The latter were ring-opened by treatment with hydroxylamine in the presence of bicarbonate to give the dioximes of the corresponding 2-alkylsuccinaldehydes, which were then reduced to the 2-alkylpurescines (1,4-diaminobutanes).Ring-opening of 2,3-dimethylpyrrole followed by reduction of the dioxime gave 1,2-dimethylputrescine; the same sequence gave 1,3-dimethylputrescine from 2,4-dimethylpyrrole, while 3,4-dimethylpyrrole did not ring-open and gave the dioxime of 3,4-dimethylmaleimide.