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