A compound 3 wherein R2 is hydrogen, R4 and R5 are hydrogen or methyl, and {HEAD ~ X} is hydrogen, fluoro or {TAIL ~ chloro} 
is
A compound 3 wherein R2 is hydrogen , R4 and R5 are hydrogen or methyl , and { HEAD ~ X } is hydrogen , fluoro or { TAIL ~ chloro }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL