Natural products

get chiral centers. mwt > 300

raw material http://zinc15.docking.org/catalogs/natprod/substances.smi:zinc_id+mwt+inchikey+purchasability+preferred_name+num_chiral_centers?count=all

1. filtered purch (mwt>=300, chiral_centers>=2, purchasable, de-duplicate)

2. unfiltered purch (purchasable, deduplicate)

3. top 100 of all, deduplicated