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Assembly of the gephyrotoxin ring system via a [4+1] approach to 3-pyrrolines

✍ Scribed by William H. Pearson; Yam-Foo Poon

Publisher
Elsevier Science
Year
1989
Tongue
French
Weight
331 KB
Volume
30
Category
Article
ISSN
0040-4039

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✦ Synopsis

Heating azidcdienes 19 at 70Β°C produced the tricyclic 3-pyrrolines 20 and 21 in one operation. The diastereoselectivity of this process was examined, and found to be controlled by the conformation of the cyclization precursor. Compound 20d incorporates the basic features of gephyrotoxin 3.

Fused bicyclic pyrrolidines and 3-pyrrolines such as 1 are commonly found as structural features of naturally occurring compounds. We have recently reported a direct method for the assembly of such ring systems based on the innamolecular cyclization of azides with electron-rich 1,3-dienes (eq. 1). 112 The presence of an electron-donating group @DG) at the position shown is crucial for the proper outcome of this cycloaddition/rearrangement,~ and provides a useful functional group for the further elaboration of the resultant 3-pyrroline 2. We wish to report the application of this method to the assembly of the tricyclic skeleton of the muscarinic antagonist gephyrotoxin 3.4 The

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