In {HEAD ~ the process}, an alkyl β alkoxy β iminopropionate salt is reacted first with a suitable alkanol to form {TAIL ~ an orthoester} intermediate in situ 
In { HEAD ~ the process } , an alkyl β alkoxy β iminopropionate salt is reacted first with a suitable alkanol to form { TAIL ~ an orthoester } intermediate in situ
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH