Question

Notice that there are actually 3 chiral centers in the (1S)-[endo]-(-)borneol substrate. C1 and C2 are obvious. What is the other center? Is the absolute configuration at this center R or S?

Answer 1

Answer:

C5 and its absolute configuration is R

Explanation:

A chiral center is a carbon atom (C) which is bonded to four different groups, generating optical activity in the molecule.

The first two chiral centers are:

• C1: bonded to OH, H, the carbon chain (seen from left to right) and the carbon chain (seen fron rigth to left).
• C2: bonded to CH3, the above C and its CH3, the carbon chain (seen from left to right) and the carbon chain (seen fron rigth to left).

The thrid chiral  center is C5, which is bonded to H, the above C and its CH3, the carbon chain (seen from left to right) and the carbon chain (seen fron rigth to left).

The absolute configuration of it is R (clockwise)