or R1 is a 2 nitrobenzyloxycarbonyl of the formula ##STR48## wherein R9 and {HEAD ~ R10} are {TAIL ~ H}, C1 C6 alkoxy, or R9 and R10 taken in combination are O CH2 O ; and 
are
or R1 is a 2 nitrobenzyloxycarbonyl of the formula # # STR48 # # wherein R9 and { HEAD ~ R10 } are { TAIL ~ H } , C1 C6 alkoxy , or R9 and R10 taken in combination are O CH2 O ; and
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH