Stereocontrolled preparation of spirocyclic ethers by intramolecular trapping of oxonium ions with allylsilanes

Leo A. Paquette, Jinsung Tae

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

The stereoselectivity of the spontaneous intramolecular cyclization of 2-(benzenesulfonyl)-2-(4-((trimethylsilyl)methyl)-4-pentenyl)tetrahydropyrans substituted by alkyl groups at various ring positions has been examined. For the 4- and 6-methyl derivatives, formation of the spirocyclic center occurs exclusively anti to the methyl. The outcome in the 5-methyl example is a 3.7:1 syn/ anti split. For the trans-4,6-dimethyl derivative, the substituents act in a reinforcing manner and direct cyclization uniquely in one direction. Both the cis and trans bicyclic ethers ring close on that π-surface of the intermediate oxonium ion syn to the angular hydrogen. The results are rationalized in terms of the predilection of the associated oxonium ions for nucleophilic capture via a chairlike or twist-boat transition state.

Original languageEnglish
Pages (from-to)7860-7866
Number of pages7
JournalJournal of Organic Chemistry
Volume61
Issue number22
DOIs
Publication statusPublished - 1996 Nov 1

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

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