L. Troisi et al., Palladium (II) catalyzed regioselective lactonization of steroids. Chemoselective construction of novel estrone derivatives, TETRAHEDR L, 40(9), 1999, pp. 1771-1774
Palladium acetate and 1,4-bis(diphenylphosphino)butane (dppb) catalyze regi
oselective cyclocarbonylation of 4-allylsteroids forming exclusively 7-memb
ered ring lactones with excellent yields (96-98 %). The stereoselective add
ition of an epoxide ring on the side-chain of steroids is realized by coupl
ing the carbonyl group of the cyclopentanone ring of the steroid with 2-ben
zothiazolylchloromethyllithium 1 or 4,4-dimethyl-2-oxazolinylchloroalkylith
iums 2 and 3. (C) 1999 Published by Elsevier Science Ltd. All rights reserv
ed.