Oxidation of olefins by palladium(II): Part 17. An asymmetric chlorohydrin synthesis catalyzed by a bimetallic palladium(II) complex
Previous studies showed that oxidation of α-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 β-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.
El-Qisairi, Arab,Henry, Patrick M.
p. 50 - 60
(2007/10/03)
ASYMMETRIC HALOGENATION OF CAMPHOR-10-SULFONIC ACID DERIVED ESTERS: AN EFFICIENT NEW ROUTE TO ENANTIOMERICALLY PURE HALOHYDRINS AND EPOXIDES.
Successive treatment of chiral esters 1 with LDA/Me3SiCl and NBS or NCS gave crystalline α-haloesters 3 which furnished halohydrins 4 and terminal epoxides 5 in high e.e..
Oppolzer, Wolfgang,Dudfield, Philip
p. 5037 - 5040
(2007/10/02)
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