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