Scheme 3 illustrates {HEAD ~ a method} of synthesizing {TAIL ~ the R and S enantiomers} of the starting materials of the formula VII wherein X is sulfur 
Scheme 3 illustrates { HEAD ~ a method } of synthesizing { TAIL ~ the R and S enantiomers } of the starting materials of the formula VII wherein X is sulfur
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH