Self-sensitized photooxidation of protoporphyrin IX and related free

Feb 22, 1984 - We now report the isolation from gum mastic of a novel bicyclic triterpenoid, 2,6 the .... and Related Free-Base Porphyrins in Natural ...
1 downloads 0 Views 421KB Size
2477

J . Am. Chem. SOC. 1984, 106, 2477-2479

151 x=o 161 X=H2

171

of (6) (KMn04-H20/PhH-n-Bu4N+Br-; room temperature) gave +33' (c 0.45 in (+)-ambreinolide (7), mp 143-144 OC,DI.[ CHCI,), identical in every respect with an authentic sample." While other partially cyclized triterpenoids have been described, these normally appear to be products of aberrant modes of cyclization" (or laboratory synthesisI2). One example is the aforementioned ambrein, in which partial cyclization has occurred at both ends of the squalene chain. In contrast, the diol 2 is the first6 example of a bicyclic triterpenoid that retains all of the regie and stereochemical features necessary for continued cyclization and occurs in a system that clearly has the enzyme(s) needed for more complete cyclization.

- I , , , , * -