Extractives of Mammea americana L. Part III. Identification of new coumarin relatives of mammea B/BA, B/BB, and B/BC having 5,6-annulation and higher oxidation levels

Abstract

Six new 4-n-propylcoumarins, all having 5,6-annulation and a higher oxidation level than the mammeas B/BA, B/BB, and B/BC, to which they are related, have been identified in the seed-extract from Mammea americana L. A group of three ((VIa–c) all contain an α-(hydroxyisopropyl)dihydrofuran ring and are differentiated by 3-methylbutyryl, 2-methylbutyryl, and butyryl substituents at the coumarin C-8. They have been deacylated to a common product (VIIIa), which has been synthesised. Compounds (VIa–c) have been obtained by partial synthesis from mammea B/BA, B/BB, and B/BC, respectively. Two further compounds are similar but contain a cyclic peroxide feature (XVa and b). The sixth compound is a hydroperoxide (XVI). Structural evidence is based on a combination of spectral information, the results of chemical degradation, and partial synthesis.