The intramolecular cycloaddition of azides with ω-chloroalkenes. A facile route to (±)-swainsonine and other indolizidine alkaloids
✍ Scribed by William H. Pearson; Ko-Chung Lin
- Publisher
- Elsevier Science
- Year
- 1990
- Tongue
- French
- Weight
- 348 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
A potentialb general route to the I-asabi~clo[n.m.O]alkune skeleton of various alkaloids is embodied in the intramolecular 1 J-&polar cycknuidition of aliphatic askies with axhloroalkenes. Cycloaddition is followed &Y rearrangement and intramolecular N-alkytation, @or&ng bicyctic iminium ions 1 in one operation. The application of this method to the synthesis of (f)-Gconiceine 6, (IS,2R&R)-indolizidine-1,2-diol 13 and (-)-swainsonine 15 is described.
Bicychc saturated heterocycles such as the pyrrokzidine. indolixidine and quinolixidine alkaloids am widespread in nature. We have been interested in developing general methods for the construction of such skeleta.
Recently, we reported that the intramolecuhu 13-dipolar cycloaddition of aliphatic axides with certain types of electron rich 1,3-butadienes produces pyrroliidines and indolixidines in one operation.1 To extend this type of strategy, we have examined the intramolecular cycloaddition of azides with other types of functionalized alkenes.
Herein we report that alkenes bearing ~hloroalkyl groups are excellent dipolarophiles in azide cycloadditions, and lead to useful bicyclic iminium ions by a rearrangement / alkylation sequence. This technique allows the assembly of bicyclic nitrogen containiig heterocycles in one operation, and is illustrated by short and efficient syntheses of three