The reaction step can be conducted in {HEAD ~ the presence} of an organic solvent and {TAIL ~ a base} 
of
The reaction step can be conducted in { HEAD ~ the presence } of an organic solvent and { TAIL ~ a base }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL