Simple syntheses of N-alkylated spermidine fragments and analogues of the spermine alkaloid kukoamine A

Acylation of a variety of amines with succinimidyl N-trityl-β-alanyl-γ-aminobutyrate and N-trityl-γ-aminobutyryl-β-alaninate, readily obtained through coupling of succinimidyl N-trityl-β-alaninate with trimethylsilyl γ-aminobutyrate and of N-trityl-γ-aminobutyric acid with methyl β-alaninate, respectively, followed by LiAlH4 reduction, produced N-monoalkylated spermidine fragments and analogues of the spermine alkaloid kukoamine A. The applicability of this methodology on the solid phase was also demonstrated.