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