DIASTEREOSELECTIVE SYNTHESIS OF CIS-3-ALKYLPYRROLIZIDINES AND 3,5-ALKYLPYRROLIZIDINES

Cis-3 and 3,5-substituted pyrrolizidines can be prepared from beta-ena minolactones. substituted pyrrolidinoketones lead to these compounds b y an amino reductive annelation with a low diastereomeric excess, but a best access to these azabicycles consists in preparing cis-2,5-disub stituted pyrrolidines which are then transformed into the expected het erocycles.