Structure elucidation of longikaurin A and longikaurin B, new biologically active diterpenoids from Rabdosia longituba and chemical conversion of oridonin into dihydrolongikaurin A

Abstract

Biologically active diterpenoids longikaurin A (1) and longikaurin B (2) were isolated, together with the known kamebakaurin (5), from the leaves of Rabdosia longituba and their structures were elucidated from spectral and chemical evidence. Oridonin (9) was chemically converted into (16R)dihydrolongikaurin A (16).