Effect of ligands on the divalent palladium- catalyzed carbon-carbon
coupling reactions. Highly enantioselective synthesis of optically active
g-butyrolactones*
Xiyan Lu** and Qinghai Zhang
Laboratory of Organometallic Chemistry, Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai
200032, China
Abstract: In the palladium (II) -catalyzed enyne coupling reactions,
the nitrogen-containing ligand plays the same role as the halide ion
to inhibit the b-hydride elimination. Employing
the pymox or bisoxazoline as ligands, the catalytic asymmetric cyclization
of (Z) -4'-acetoxy-2'-butenyl 2-alkynoates initiated by acetoxypalladation
was established with high efficiency (up to 92% ee) to afford the optically
active g-butyrolactones.
* Lecture presented at the XIXth International Conference
on Organometallic Chemistry (XIX ICOMC) , Shanghai, China, 23-28 July
2000. Other presentations are published in this issue, pp. 205-376.
** Corresponding author
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