Intramolecular cycloadditions of azides with olefins: Synthetic approaches to pyrrolizidine and indolizidine alkaloids.

摘要

Alkyl azides were found to undergo intramolecular cycloadditions with various olefins to provide 4,5-dihyro-3H-pyrroles, 2,3,5,6,7,7a-hexahydro-1H-pyrrolines (pyrrolizidines) and 1,2,3,5,6,7,8,8a-octahydroindolizines (indolizidines). Thermolysis of racemic mixtures of (Z)-7-azido-5-(methoxy)methoxy-3-phenylthio-1,3-heptadiene and (Z)-8-azido-5-(methoxy)methoxy-3-phenylthio-1,3-octadiene provided racemic mixtures of (1R*,7aR*)-2,3,5,7a-tetrahydro-1-(methoxy)methoxy-7-phenylthio-;Heating (S)-5-azido-3- ((benzyl)oxy) methoxypentene, which was derived from (S)-malic acid, at 120