Stereochemistry and opioid receptor affinity of 2,4‐dipyridine‐3,7‐diazabicyclo[3.3.1]nonanones ‐ influence of the substituent in position N7

The stereochemistry the 2,4‐di‐arene substituted 3,7‐diazabicyclo[3.3.1]nonan‐9‐one 1,5‐dicarboxylate skeleton was found to be regulated by the kind of substituents attached to the arene rings as well as to the nitrogens N3 and N7. Conformational isomers, i.e., chair/chair, boat/chair and chair/boat, in addition to cis/trans conflgurational isomerism with respect to the arene rings were reported. Since the analgesic potency of the diazabicyclononanones, which is related to their affinity toward the κ‐opioid receptor, is governed by the stereochemistry of the molecules, the influence of the substituents at nitrogen N7 was studied herein. The various differently N7 substituted diazabicyclononanones were found to crystallise in a highly symmetrical chair/chair conformation. However, beside HZ2 none of the compounds exhibits high affinity to the κ receptor. In contrast, some compounds with affinity to the μ receptor could be identified. In addition, the N7‐(4‐carboxybenzyl) substituted compound was found to have affinity to the δ receptor in the submi‐cromolar range of concentration.     

6,7,14,15-Tetrahydro-15aH-azocino[1,2-a:6,5-b′]diindole. Synthesis of a novel pentacyclic ring system

In search of new lead structures for potent allosteric enhancers of antagonist binding to muscarinic M₂ receptors, a novel heterocyclic ring system, 6,7,14,15-tetrahydro-15aH-azocino[1,2-a:6,5-b′]diindole, has been synthesized. The new ring skeleton was obtained from indol-2-yl-acetic acid in three steps.     

On cluster kinetics and MBE growth

Based on the model of a so-called Near Surface Transition Layer (NSTL) proposed by HERMAN and ANDERSSON we discuss the possible role of clusters during MBE growth. Moreover, intentional use of small clusters instead of single atoms as beam constituents may contribute to improvements in crystal quality even at low substrate temperature and high growth rate.