NOVEL ANGULAR PYRANOCOUMARINS FROM BORONIA-LANCEOLATA

The aerial parts of Boronia lanceolata have yielded eight coumarins. Four of these were characterized by NMR analysis as a novel series of angular pyranocoumarins 8-methyl-8-(4-methylpent-3-enyl)-2H-benzo-[1,2-b:5,6-b']-dipyran-2-one (5-deoxyprotobruceol-I regioisomer), 8-methyl-8-(4-hydroperoxy-4-methylpent-2 [1,2-b:5,6-b']-dipyran-2-one (5-deoxyprotobruceol-II hydroperoxide regioisomer) and the two stereoisomers of 8-methyl-8-(3 xi-hydroperoxy-4-methylpent-4-enyl)-2H-benzo- [1,2-b:5,6-b']-dipyran-2-one (5-deoxyprotobruceol-III-hydroperoxide regioisomer). The remainder were identified as 7-hydroxy-8-geranylcoumarin, xanthyletin, demethylsuberosin and 7-hydroxy-6-(2(R)-hydroxy-3-methylbut-3-enyl)coumarin, which also appears to be novel.