Q
How to convert a library of linear precursors into a library of macrocycles?
A.
Sketch the reaction in the 
molecule editor with a special bond (dotted) which means
    anything between R1-R2
    
    

- The bond can be added using 'Distance Bond' tool in the editor.
- 
Save the reaction to a chemical table 
- Read in your precursors sdf file
- Then you can just apply this reaction (Right Click on the reaction and select Apply Reaction)
    to your data.
- A new chemical table will be made containing the macrocycles.