R2 represents C1 6 alkyl, phenyl, {HEAD ~ 1 3 phenyl} or {TAIL ~ 1 4 COOR5}, or 
R2 represents C1 6 alkyl , phenyl , { HEAD ~ 1 3 phenyl } or { TAIL ~ 1 4 COOR5 } , or
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH