A synthesis of (+)-lentiginosine and its pyrrolizidine analogue was accomplished in six steps, starting from L-(+)-tartaric acid. The key step of these syntheses involves the intramolecularcyclization of α-sulfinyl carbanions for the construction of the indolizidine or pyrrolizidine ring.
Samarium Diiodide-Promoted Cyclization of <i>N</i>-(ω-Iodoalkyl)imides to Polyhydroxylated Indolizidinones and Pyrrolizidinones: Synthesis of (+)-Lentiginosine