{HEAD ~ R10} is independently selected from {TAIL ~ the group} consisting of H, alkyl, and arylalkyl 
is independently selected from
{ HEAD ~ R10 } is independently selected from { TAIL ~ the group } consisting of H , alkyl , and arylalkyl
HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH