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