[reaction: see text] Using 5b as a common intermediate, the first asymmetric synthesis of (-)-epiquinamide (4) and a formal asymmetric synthesis of (-)-homopumiliotoxin 223G (2) is described. A key feature of our approach is the flexible introduction of a functionalized C(4) side chain to (S)-3-benzyloxyglutarimide 7 in a regio- and diastereoselective manner. Utilization of a tandem Swern oxidation-Grignard addition strategy efficiently prevented racemization. An unexpected NaN(3)-promoted methanesulfonic acid elimination yielded 17, a reaction which could be useful for the syntheses of 8-dehydrodesmethylpumiliotoxins such as alkaloid 235C (3).
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