R2 and R3, together with the carbon atom to which they are bonded, are {HEAD ~ a cyclopropylidene, cyclobutylidene}, cyclopentylidene, or {TAIL ~ cyclohexylidene} 
R2 and R3 , together with the carbon atom to which they are bonded , are { HEAD ~ a cyclopropylidene , cyclobutylidene } , cyclopentylidene , or { TAIL ~ cyclohexylidene }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL