| Abstract
| - Dienes 23 and 54, prepared from epoxy alcohol 9 via oxazolidinones 15 and 51, respectively,underwent ring-closing metathesis with Grubbs's catalyst to give azacyclooctenes 26 and 55.Treatment of each azacyclooctene with m-chloroperoxybenzoic acid afforded β-epoxide 28 from 26and α-epoxide 61 from 60. Basic hydrolysis of each of these oxazolidinones was accompanied bytransannular attack at the epoxide by nitrogen, resulting in 2-(O-benzyl)-7-deoxyalexine (29) and1,2-di-(O-benzyl)australine (62). The latter was converted to the alkaloid australine (3) uponhydrogenolysis. Attempts to effect ring-closing metathesis of dienes 37, 38, and 46 were unsuccessful,suggesting that, while one allylic oxygen substituent can be tolerated by Grubbs's catalyst, twocannot.
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