Naturally occurring quinones. Part XXII. Terpenoid quinones in Cordia spp.
Cordiachromes A–F are terpenoid benzoquinones isolated from the heartwood of Cordia millenii. Cordiachrome C (3; R = H) has a benzogeijerene and A (1; R = H) and B (2; R = H) have a benzocogeijerene skeleton. Cordiachromes D–F are methoxy-derivatives of A–C, respectively. All six are optically inactive. Biogenetically they appear to be related to alkannin, which occurs in the same family (Boraginaceae). The distribution of cordiachromes in other Cordia spp. is surveyed.