Synthesis of ent-thallusin.
[reaction: see text] A three-step route from sclareol oxide (6) to bromo ester 4 in 53% overall yield was achieved using the efficient oxidation of an allylic bromide to an enal with bis(2,4,6-trimethylpyridine)silver(I) hexafluorophosphate in DMSO. Stille coupling of bromo ester 4 with stannylpyridine 5 gave the trimethyl ester of ent-thallusin in 54-92% yield by the stoichiometric conversion of 4 to a vinyl palladium intermediate prior to the addition of 5 to the reaction.
Gao
Xiaolei
X
Department of Chemistry, Brandeis University, Waltham, Massachusetts 02454-9110, USA.
Matsuo
Yoshihide
Y
Snider
Barry B
BB