Oxidation of olefins by palladium(II) Part 17. An asymmetric chlorohydrin synthesis catalyzed by a bimetallic palladium(II) complex

摘要

Previous studies showed that oxidation of cl-olefins with monometallic catalysts containing chiral diphosphines and diamines gave chlorohydrins with poor to good enantioselectivites (28-82% ee). The present studies demonstrate that bimetallic catalysts containing a beta-triketone and bridging chiral diphosphine and diamines are excellent catalysts for this reaction giving enantioselectivites considerably higher than the monometallic catalysts. Enantioselectivities were more than 50% for most olefins tested. The highest optical purities were 94% ee for propene and 93% ee for allylphenyl ether. A useful feature of this asymmetric synthesis is the fact it is a net air oxidation. (C) 2000 Elsevier Science S.A. All rights reserved. [References: 20]