{HEAD ~ The compound} 2 wherein {TAIL ~ R4} is an substituted or unsubstituted phenyl or thienyl group 
wherein
{ HEAD ~ The compound } 2 wherein { TAIL ~ R4 } is an substituted or unsubstituted phenyl or thienyl group
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH