In particular, for example, a benzyl or methoxymethyl group is used as {HEAD ~ the protective group} and a Grignard reagent is used as {TAIL ~ the organometallic reagent} 
In particular , for example , a benzyl or methoxymethyl group is used as { HEAD ~ the protective group } and a Grignard reagent is used as { TAIL ~ the organometallic reagent }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL