The manuscript of Fosu and Vlaisavljevich explores the stereoselective ring opening catalytic polymerization of lactides. The authors have performed a thorough computational examination on a variety of different plausible reaction pathways for the key ring opening step. Considering the details presented and the computational aspects carefully addressed by the authors, I dare to say that this is how computational catalysis studies should be performed! Their discussion provides details on the different catalytic pathways, comparison with experiment, and additional fundamental understanding of the role of noncovalent interactions between the salan catalyst and the substrate. I do not have any major comments or any concerns about this work. Publish!

Minor comments:
- I would add on Figure 4a, under each molecular geometry, the ΔG values of the corresponding TS, or their ΔΔG (their relative difference). That would help the reader to better evaluate the first TS of the considered pathways.
- Table 1, please add the relative reaction barriers of TS2, either as a separate column or in parenthesis next to the reported TS2 values. Again, this would help the reader to better follow the technical analysis.
- Some references appear as “?”, e.g. page 1, bottom of right column, or page 2, top of right column.