Intramolecular Cyclization During Bromination of the Quinoline Alkaloid Haplophyllidine.

Bromination of the furanoquinoline alkaloid haplophyllidine by molecular bromine and N-bromosuccinimide was accompanied by intramolecular cyclization to form mixtures of new compounds containing additional penta-, hexa-, and spirocyclic rings incorporating the prenyl group of haplophyllidine. The structures and absolute configurations of the chiral centers of all four bromo-derivatives were elucidated using a combination of NMR spectroscopic methods and X-ray crystal structure analyses.