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