{TAIL ~ Substituents R1}, R2, R3 and R4 have the same meaning as defined in {HEAD ~ the specification} 
{ TAIL ~ Substituents R1 } , R2 , R3 and R4 have the same meaning as defined in { HEAD ~ the specification }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD