I always encounter polycyclic compounds at work but I do not see many resources explaining how to name them. I know the basic of naming of bicyclic compounds (the ones placed inside square brackets) which helped me figure out the naming of polycyclic compounds. The latter uses exponents in their notation. For example, the name of the first compound is tricyclo[4.3.1.1^{3,8}]undecan-4-amine (the supposedly exponents are inside the brackets "{ }"). How are the 3 and 8 assigned?
The second compound is named 6-(propan-2-yl)-4,5-diazatricyclo[6.2.2.0^{?,?}]dodeca-2(7),5-dien-3-one. The supposedly exponents do not show due to typographical error. How is the exponents for this one determined?
The bridgehead carbon atoms are at positions 3 and 8 of the structure.
That's why 3 and 8 are assigned the bracket.
According to IUPAC, the procedure is as follows:
1. Find the largest possible cycle (in red) = the main cycle that has more atoms on one side (black spheres, first number in square brackets) and fewer atoms on the other side (red spheres, second number in square brackets).
2. Find the main bridge (i.e. the link on the main cycle that divides it into the smaller and larger number of atoms) so that it has as many atoms as possible outside the main cycle (blue spheres). In the second case it is clear, in the first case both bridges have one atom, but the black one has priority in numbering. This main bridge will be the third number in the square bracket.
3. Find the side bridge (the only one left). This will be the fourth number in the square bracket (turquoise spheres) with the exponent of the two atoms that make up the secondary bridge.
In the second case, the bracket will be as follows: [6.2.2.0exp2.7].
I don't know if that is clear enough. Hope it helps...
This answer is clear enough! It took me awhile to figure out the numbering of the atoms in the main cycle.
Thank you! Tereza Navrátilová and also Ranbir Kumar
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