Synthesis of oxygen heterocycles via alkynyltungsten compounds*
Rai-Shung Liu
Department of Chemistry, National Tsing-Hua University,
Hsinchu, Taiwan ROC
Abstract: This short review article covers some useful applications
of alkynyltungsten compounds to the syntheses of complex lactones. Two
types of cyclizations will be emphasized: (1) cycloalkenylation of tungsten-alkynol
compounds with aldehydes to give a-alkylidene oxacarbeniums, further
leading to a-alkylidene lactones and (2) intramolecular [3+2]-cycloaddition
of epoxides to give bicyclic lactones. The new methodologies can provide
a short synthesis of enantiopure lactones such as (-) -epilitsenolide
C2, (+) -listenolide C1, (+) -isodihydromahubanolide
A, (+) -blastmycinone, and (-) -epi-blastmycinone.
* 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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