Radical Cyclization in Heterocycle Synthesis. 11. A Novel Synthesis of α,β-Disubstituted γ-Lactones via Sulfanyl Radical Addition−Cyclization Using Hydroximates as a Tether
2000-09-15T00:00:00Z (GMT) by
A combination of sulfanyl radical addition−cyclization of dienes connected with hydroximates and subsequent conversion of the resulting cyclic hydroximate to the lactones provides a novel method for the construction of α,β-disubstituted γ-lactones. Upon treatment with thiophenol in the presence of AIBN, dienes connected with hydroximates smoothly underwent sulfanyl radical addition−cyclization to give cyclic <i>cis</i>- and <i>trans</i>-hydroximates. Hydrolysis of cyclic hydroximates gave the desired <i>cis</i>- and <i>trans</i>-lactones in high yield. This method was successfully applied to the practical synthesis of (±)-oxo-parabenzlactone.
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