# How many stereogenic centers exist in the atropine?

I'm pretty sure that both C bonded to N are stereogenic centers. I don't know about the others, any help? Is this correct?

• I think there is only one chiral center in atropine. Jul 14, 2021 at 16:54
• @Curt F.: The ring is symmetric so all three carbon centers shown in are not chiral. The sole chiral center is the $\alpha$-carbon to carbonyl group. Jul 14, 2021 at 17:01
• Hi, actually I meant stereogenic center, I don't know if it's different from the definition of chiral center. Jul 14, 2021 at 20:34

I assume the OP means atropine in which case the structure presented has an extra methylene group. The renderings of a single enantiomer of atropine by ChemDraw 20.1 and JSmol are shown below.

Using the terminology of Mislow and Siegel (https://doi.org/10.1021/ja00323a043), the bridgehead carbons and the benzylic carbon are stereogenic and chirotopic, Thus, the R/S designation. The remaining carbon labeled "r" is stereogenic but achirotopic (r/s). Therefore, there are four stereogenic centers three of which are chirotopic.

In this question you can look at the IUPAC definition of the chiral center. According to the definition, carbons that are attached to nitrogen are chiral centers — they have 4 different chemical groups attached to them. The $$\alpha$$-carbon to the ester group is also a chiral center. However, the third carbon (from top to bottom) that you circled is not a chiral center because two groups from the cycle are identical.

• Yes, nevertheless, the "third carbon" is a pseudoasymmetric center (r or s). Jul 14, 2021 at 18:18
• IUPAC defines chirality centre (doi.org/10.1351/goldbook.C01060) as An atom holding a set of ligands in a spatial arrangement which is not superposable on its mirror image. That doesn't necessarily mean that it has to be four different groups, although that is a convenient rule of thumb. Jul 14, 2021 at 18:23
• @Loong you're right but question asks for chiral centers Jul 14, 2021 at 18:31
• @Martin-マーチン in definition that you referred to it's written Cabcd. And it's also written that this is a generalization of concept of asymmetric carbon atom which is defined as I wrote (doi.org/10.1351/goldbook.A00479). If I am wrong somewhere, please correct me. Jul 14, 2021 at 18:35
• Hi, actually I meant stereogenic center, I don't know if it's different from the definition of chiral center. Jul 14, 2021 at 20:31