Very Short and Efficient Syntheses of the Spermine Alkaloid Kukoamine A and Analogs Using Isolable Succinimidyl Cinnamates

Direct selective acylation of the primary amino functions of spermine and spermidine with a variety of isolable succinimidyl cinnamates, followed by catalytic hydrogenation, gave high yields of the spermine alkaloid kukoamine A and analogs suitable for structure-activity relationship studies. Suitable succinimidyl cinnamates were readily obtained through Wittig reaction of aromatic aldehydes with the ylides Ph3P=CRCO2Me, followed by saponification and activation with N-hydroxysuccinimide in the presence of N,N′-dicyclohexylcarbodiimide.