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