Extractives of Mammea americana L. Part IV. Identification of new 7,8-annulated relatives of the coumarins mammea A/AA, A/AB, B/AA, and B/AB, and new members of the 6-acyl family B/AA, B/AB, and B/AC
Abstract
Six new coumarins of the 4-n-propyl series and two of the 4-phenyl series have been identified from Mammea americana L. Three of the former, mammea B/AA, B/AB, and B/AC, have the 5,7-dihydroxy-4-n-propylcoumarin core carrying an 8-(3-methylbut-2-enyl), grouping, and are differentiated by the 6-acyl substituent, which is 3-methylbutyryl (Ia), 2-methylbutyryl (Ib), or butyryl (Ic). The other three 4-n-propyl compounds have the same core but a 7,8-fused α-(hydroxyisopropyl)dihydrofuran system. The same three acyl variations are present, but at position 6 (VIIa–c). The two 4-phenylcoumarins found have also a 7,8-fused α-(hydroxyisopropyl)di-hydrofuran system and possess either a 6-(3-methylbutyryl) or a 6-(2-methylbutyryl) substituent (VIa and b). There is mass spectral evidence of a shorter-chain member.
Structural evidence is based on spectral studies, supported by chemical interconversions involving mammea compounds of known structure.
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