The drug 6, wherein {HEAD ~ R1} is a n pentyl group or {TAIL ~ a 2methylhexyl group} 
is
The drug 6 , wherein { HEAD ~ R1 } is a n pentyl group or { TAIL ~ a 2methylhexyl group }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL