Question

The number of stereogenic centre(s) present in the given alkaloid is _ _ _. (answer in integer)

Hint:

While counting stereogenic centres, count only stable tetrahedral atoms attached to four different groupsDo not count aromatic carbons, alkene carbons, or rapidly inverting amine nitrogen

Answer 1

Correct Answer: 4

Step 1: Understand stereogenic centres.
A stereogenic centre is usually an sp$^3$ carbon atom attached to four different groupsChanging the configuration at such a centre gives a stereoisomer

Step 2: Examine the alkaloid structure.
The given alkaloid contains a quinoline ring system and a bicyclic amine portionThe aromatic carbons are sp$^2$ hybridized and cannot act as stereogenic centres

Step 3: Locate stereogenic centres in the side chain.
The carbon bearing the hydroxyl group is attached to four different groupsTherefore, it is one stereogenic centre

Step 4: Locate stereogenic centres in the bicyclic amine part.
The bicyclic quinuclidine-type portion contains multiple asymmetric sp$^3$ bridgehead/substituted carbonsThese carbons are attached to different paths in the ring system and hence act as stereogenic centres

Step 5: Count valid stereogenic centres.
On careful inspection, four sp$^3$ carbons satisfy the condition of being attached to four different groups

Step 6: Exclude non-stereogenic atoms.
The nitrogen atom is not counted because rapid inversion at nitrogen generally prevents stable configurational chiralityThe alkene and aromatic carbons are also not counted because they are sp$^2$ hybridized

Step 7: Conclusion.
Thus, the number of stereogenic centres present in the given alkaloid is
\[ \boxed{4} \]