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