A compound 15, wherein Ra, {HEAD ~ Rb} and Rc are {TAIL ~ each hydrogen} 
are
A compound 15 , wherein Ra , { HEAD ~ Rb } and Rc are { TAIL ~ each hydrogen }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL