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