Studies have shown that one stereoisomeric certain types of neurodegenerative disorders, system, as illustrated in structure B, and that form of compound A is an effective agent against Recognize that structure A contains a decalin-type the nitrogen can be treated just like a carbon.

(a) Use your model kits to analyze the ring juncture. Make models of the cis as well as the trans ring juncture of structure B. You should have four different models. Identify the stereochemical relation between them as diastereomeric or enantiomeric. Draw the isomers and assign the R or S configuration to the stereocenters at the ring fusion.
(b) Although the trans ring juncture is the energetically more favorable one, the compound with cis ring juncture is the stereoisomer of structure A that shows biological activity. Make models of structure A that have the cis ring juncture exclusively. Set the stereochemistry of C3 as shown in structure A and vary the center at C6 in relation to that at C3. Again, there are four different models. Draw them and convince yourselves that none of them are enantiomers by assigning the R or S configuration to all four of the stereocenters in each of the compounds.
(c) The stereoisomer of compound A that shows the greatest biological activity has a cis ring fusion with substituents at C3 and C6 that are both equatorial. Which of the stereoisomers that you drew encompasses these constraints? Identify it by recording the absolute configuration at C3, C4a, C6, and C8a.

Transcribed Image Text:

8a NH NH 4a