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