Highly selective atomic chiral index and its application to automatic assignment of chiral centers in chiral compounds

- Highly selective atomic chiral indices were suggested.
- The uniqueness test was performed by virtual and reality atomic data sets.
- The chiral centers of chiral compounds were automatically assigned.

As the requirement of chiral compounds increases, the studies on asymmetric catalytic synthesis and separation are of interest. For these kinds of researches, identifications of chiral centers are often required. However, it's time-consuming, especially for the compounds with multiple chiral centers. Thus, a method to automatically identify chiral center based on highly selective atomic chiral index was suggested in this paper. At first, an atomic chiral index-aEAID was suggested based on molecular index EAID (one of the most highly discriminating indices). The uniqueness test of aEAID was performed by a virtual data set of 3,851,864 atoms, no degeneracy occurred. However, the uniqueness test was performed by NCI database of 3,814,521 atoms (NCI database were taken from the network), 12 pairs of degenerated atoms within 7 pairs of molecules were found. In order to improve the discriminating ability of aEAID, a distance factor was introduced into aEAID to generate a new highly selective atomic chiral index-d-aEAID. The two atomic data sets above were also used to test the uniqueness of the index-d-aEAID, and there was no degeneration. Furthermore, the two atomic indices, i.e., aEAID and d-aEAID, were applied to automatic identification of chiral centers for a total of more than 100,000 chiral compounds for three data sets (each compound possesses 1-38 chiral centers), and both atomic indices correctly identified all the chiral centers.