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