Syntheses of ficuseptine, juliprosine, and juliprosopine by biomimetic intramolecular chichibabin pyridine syntheses

Abstract

(Chemical Equation Presented) Biomimetic intramolecular Chichibabin pyridine syntheses using two molecules of an aldehyde and 4-aminobutanal dimethyl acetal (6) proceed efficiently in AcOH at 95°C to give 2,3-dihydro-1H-indolizinium salts. Reaction occurs at 25°C if 1-pyrroline (5) is used instead of 6. This reaction has been used for a one-step synthesis of ficuseptine (1) and the first syntheses of juliprosine (2) and juliprosopine (17t), which is now assigned as the trans stereoisomer. © 2005 American Chemical Society.