{TAIL ~ Methods} to activate the carboxylic acid include reacting said acid with one or more molar equivalents of oxalyl chloride or thionyl chloride to afford {HEAD ~ the carboxylic acid chloride} in a suitable solvent such as dichloromethane, chloroform or diethyl ether 
{ TAIL ~ Methods } to activate the carboxylic acid include reacting said acid with one or more molar equivalents of oxalyl chloride or thionyl chloride to afford { HEAD ~ the carboxylic acid chloride } in a suitable solvent such as dichloromethane , chloroform or diethyl ether
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH