| Abstract
| - The first enantioselective total synthesis of (+)-brasilenyne (1) has been achieved in 19 linearsteps, with 5.1% overall yield from l-(S)-malic acid. The construction of the oxonin core containing a 1,3-cis,cis diene unit was accomplished with a tandem ring-closing metathesis/silicon-assisted intramolecularcross-coupling reaction. In addition, a key propargylic stereogenic center was created through a novel,highly diastereoselective ring opening of a 1,3-dioxolanone promoted by TiCl4. This reaction proceededthrough an oxocarbenium ion intermediate and the asymmetric induction was fully controlled by l-malicacid residue. The C(8) stereogenic center was set by a reagent-controlled asymmetric allylboration.
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