Structural and synthetic studies on the retrofractamides-amide constituents of Piper retrofractum

Article abstract of DOI:10.1016/S0031-9422(00)83537-2

Two new unsaturated amides, retrofractamides A and C, were isolated from the total above-ground parts of Piper retrofractum. Retrofractamide A was shown to be N-isobutyl-9(3′,4′-methylenedioxyphenyl)2E,4E,8E-nonatrienamide from spectroscopic and chemical investigations. The structure 6 for retrofractamide C was suggested from spectroscopic and chemical studies and was confirmed by a total stereoselective synthesis. The presence of sesamin and 3,4,5-trimethoxydihydrocinnamic acid as well as two higher homologues of retrofractamide A, viz. pipericide (retrofractamide B) and retrofractamide D was demonstrated. The synthesis of pipericide was also achieved.