Methylation of compound 3 with iodomethane in the presence of {HEAD ~ a base}, such as {TAIL ~ sodium hydride}, provides N methylated product of structure 5 
such as
Methylation of compound 3 with iodomethane in the presence of { HEAD ~ a base } , such as { TAIL ~ sodium hydride } , provides N methylated product of structure 5
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH