In preferred compounds of Formula I, Y is an dialkoxyphosphonate, or α hydroxyamide group and {HEAD ~ Z} is {TAIL ~ an acyl} or α ketocarbamate functionality 
is
In preferred compounds of Formula I , Y is an dialkoxyphosphonate , or α hydroxyamide group and { HEAD ~ Z } is { TAIL ~ an acyl } or α ketocarbamate functionality
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH