{HEAD ~ R7} is OH, lower alkyl, phenyl, benzyl, {TAIL ~ R3 phenyl} or R3 benzyl 
is
{ HEAD ~ R7 } is OH , lower alkyl , phenyl , benzyl , { TAIL ~ R3 phenyl } or R3 benzyl
HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH