Protobruceols: New 6-C-Monoterpenyl-5,7-Oxygenated Coumarins From Eriostemon Brucei

Natural Product Letters
1992.0

Abstract

Six novel coumarins have been isolated from the aerial parts of Eriostemon brucei var. cinereus. Five had the same tricyclic nucleus [(+)-2-methyl-5- hydroxy- 2H- benzo-[1,2b:3,4b'] - dipyran-8-onel and varied only in the C-2 substituent, viz. 4- methylpent - 3 - enyl (protobruceol- I), 4 - h ydroxy - 4-methylpent-2(E)-enyl (protobruceol-11), 4- hydroperoxy- 4- methylpent- 2(E)-enyl (protobruceol-I1 hydroperoxide), 3-hydroxy-4-methylpent-4-enyl (protobruceol-III), 3 hydroperoxy - 4- methylpent - 4- enyl (protobruceol- 111 hydroperoxide). A sixth coumarin was characterised as the linear annellated isomer of protobruceol-11, (+)- 2-methyl-2-(4- hydroxy-4-methylpent-2(E)-enyl)-5-hydroxy-2H-benzo- [1,2b:5,4b'] - dipyran- 8 -one (protobruceol-IV).

Knowledge Graph

Similar Paper