{TAIL ~ A process} 2, wherein R1, R2 and {HEAD ~ R3} are hydrogen and R4 is a lower alkyl group 
{ TAIL ~ A process } 2 , wherein R1 , R2 and { HEAD ~ R3 } are hydrogen and R4 is a lower alkyl group
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH