{HEAD ~ R2} is hydrogen, nitro, {TAIL ~ amino} or mono or dialkylamino; and 
is
{ HEAD ~ R2 } is hydrogen , nitro , { TAIL ~ amino } or mono or dialkylamino ; and
HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH