Elsevier, Tetrahedron Letters, 11(53), p. 1370-1372
DOI: 10.1016/j.tetlet.2012.01.008
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The asymmetric Birch reductive alkylation has been investigated to synthesize spiroimine analogs of the neurophycotoxin (−)-gymnodimine A 1. Two types of chiral aromatic substrates, an acyclic benzamide 2 and a benzoxazepinone 3 were studied. We found that the chiral auxiliary of benzoxazepinone could be easily removed in a three step procedure to afford β-ketoester 14 that was converted into spiroimines 23–24 possessing antagonist effects on nicotinic acetylcholine receptors (nAChRs).