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