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