Synthesis of novel piperideine- and pyridine-containing long-chain fatty ester derivatives from methyl iso-ricinoleate

Abstract

Oxidative rearrangement of methyl 9-azido-12,13-epoxy-stearate 2 with MeI, NaI and DMF and short-time concomitant ultrasonication at 120 °C yields exclusively 1,4- and 1,5-azido-oxo isomers 3 and 4, whereas prolonged heating furnishes pyrrole and pyridine derivatives 5 and 6; cyclization of 3 and 4 with Ph₃P gives pyrroline 7 and Δ¹piperideine 8; and oxidative aromatization of 8 with PtO₂ yields compound 6 as an alternative route.