Quinoline alkaloids. Part 17. Mechanism of base-catalysed rearrangement of hydroxyisopropyldihydrofuroquinolones and of dihydrodimethylpyranoquinolones

Abstract

A re-investigation of the stereospecific base-catalysed rearrangement of (+)-(R)-balfourodine (1) and of (+)-(R)isobalfourodine (8) has resulted in improved methods of preparing (+)- and (–)-ψ-balfourodine, in establishing the absolute stereochemistry of the rearrangement products, and in trapping an epoxide intermediate as its methyl ether (9); a new mechanism for rearrangement is proposed.