Curariform Activity and Chemical Structure. V.¹ Syntheses in the Quinolizidine Series²

Abstract

An examination of the compounds possessing curariform activity reveals that a fused bicyclic ring system with nitrogen common to both rings is a structural feature present in many of the highly active compounds.4 For example, such a ring system is present, or thought to be present, in members of the erythrina, calabash curare, and canadine alkaloids as well as in certain active synthetic compounds.5 In view of this coincidence between curariform activity and the presence of a bicyclic, fused, nitrogen-containing ring system, model compounds based on the quinolizi-dine6 nucleus have been prepared and tested to determine whether this structural unit, by itself, is sufficient for curariform activity. The results

Molecular “Iron Maidens”: Ultrashort Nonbonded Contacts in Cyclophanes and Other Crowded Molecules

“…The X-ray structures of cyclophanes were exhaustively reviewed in 1983, [7] and from this compendium it was clear that the ''world record'' for close hydrogen-arene nonbonded contacts was to be found in Boekelheide's metaparacyclophane 3. [8,9] In this molecule, the illustrated hydrogen is only 2.11 Å from the center of the opposing benzene ring. (Hereafter, this distance, to the center of the ring, is called the H---Ar contact, [10] but nonbonded distances to specific carbon atoms are designated H---C contacts.…”

Conjugate Additions to Vinyl-Substituted Aromatic N-Heterocycles

“…53 The authors also note that in an earlier published study, product 114 was obtained in just 16% yield from a base-promoted reaction. 54…”

The crystal structure of 2,7-diacetoxy-trans-15,16-dimethyl-15,16-dihydropyrene

“…The molecule under examination (C2204H20 , Fig. 1) is a novel aromatic system in which the methyl groups reside within the cavity of the 14-n-electron system (Boekelheide & Phillips, 1963). The crystal structure analysis was undertaken in order to provide informa-…”