Substituent-Control of Two Modes of Intramolecular Reactions of Allyloxy-Silyllithiums and Propargyloxy-Silyllithiums
2005; Oxford University Press; Volume: 78; Issue: 8 Linguagem: Inglês
10.1246/bcsj.78.1520
ISSN1348-0634
AutoresAtsushi Kawachi, Hirofumi Maeda, Kohei Tamao,
Tópico(s)Asymmetric Synthesis and Catalysis
ResumoAbstract Intramolecular reactions of the [(allyloxy)silyl]lithiums and the [(propargyloxy)silyl]lithiums have been investigated. The [(allyloxy)silyl]lithiums proceed in two reaction modes depending on the electronic effect of the substituents at the terminus of the olefin. The [(allyloxy)silyl]lithiums bearing hydrogen, n-C6H13, or trimethylsilyl substituent undergo the [2,3]-sila-Wittig rearrangement to afford the lithium allylsilanolates, while those bearing the phenyl, thienyl, or triphenylsilyl substituent experience the 4-exo-trig cyclization and subsequent 1,3-cycloelimination to give the lithium cyclopropylsilanolates. On the other hand, the [(propargyloxy)silyl]lithiums preferentially undergo the 4-exo-dig cyclization over the [2,3]-sila-Wittig rearrangement in all cases.
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