Scheme I describes {TAIL ~ the synthesis} of {HEAD ~ the 5 cycloalkenyl} analogues 3, 4 and 5 
Scheme I describes { TAIL ~ the synthesis } of { HEAD ~ the 5 cycloalkenyl } analogues 3 , 4 and 5
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH