{TAIL ~ Z} is chosen from CR6 and CCOCNHR8, wherein {HEAD ~ R6} is alykl, arylalkyl, aryl, m cycloalkyl, heteroaryl, or ##STR73## wherein m=0 3 
{ TAIL ~ Z } is chosen from CR6 and CCOCNHR8 , wherein { HEAD ~ R6 } is alykl , arylalkyl , aryl , m cycloalkyl , heteroaryl , or # # STR73 # # wherein m=0 3
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH