Spiroketal Reductive Ring Opening

George Pettit, Anthony H. Albert, Peter Brown

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Both the direction and mechanism of reductive ring opening with the spiroketal 9,9-dimethyl-1,6-dioxaspiro[4.5]decane (8) have been explored. With dimedone (3) as precursor, synthesis of spiroketal 8 was realized by way of intermediates 4,5,6, and 7. Lithium aluminum hydride–aluminum chloride catalyzed reduction of spiroketal 8 was found to yield tetrahydropyran 9 in contrast to the steroidal sapogenins which undergo reductive cleavage of the tetrahydropyran ring. The mechanism of ring opening was examined using deuterium labeling (8 → 9b) combined with mass and proton magnetic resonance spectral measurements. Reductive ring opening of spiroketal 8 was thereby found to proceed by transfer of reagent hydride directly to the spirocarbon. The experimental results also suggested that reductive ring opening of relatively nonhindered spiroketals related to 8 may offer a new synthetic route to certain substituted tetrahydropyrans.

Original languageEnglish (US)
Pages (from-to)8095-8099
Number of pages5
JournalJournal of the American Chemical Society
Volume94
Issue number23
DOIs
StatePublished - Nov 1 1972

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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