REGIOSELECTIVE BROMINATION OF MULTIFLORINE AND STRUCTURES OF 3-BROMOMULTIFLORINE AND ITS MOLECULAR-COMPLEX WITH SUCCINIMIDE

The regio-specific bromination of multiflorine, an alkaloid isolated f rom Lupinus albus is described. The bromomultiflorine and its molecula r complex with succinimide have been characterized by IR and NMR spect roscopy, as well as by X-ray diffraction. The conformation in solution and in the solid state has been determined. The molecular complex for mation between 3-bromomultiflorine and succinimide molecules is the fi rst case in the class of lupine alkaloids. Both molecules of this comp lex are held together by an intermolecular hydrogen bond N-H ... N whi ch leads to a conversion of alkaloid nitrogen atom configuration. As a consequence, ring C adopts a chair conformation, whereas it is in a b oat form in 3-bromomultiflorine. (C) 1998 Elsevier Science B.V.