In general {HEAD ~ the need} for {TAIL ~ such protecting groups} will be apparent to those skilled in the art of organic synthesis as well as the conditions necessary to attach and remove such groups 
for
In general { HEAD ~ the need } for { TAIL ~ such protecting groups } will be apparent to those skilled in the art of organic synthesis as well as the conditions necessary to attach and remove such groups
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL 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 OTH