{TAIL ~ The process} employing a non chiral auxiliary in the starting material can employ either a fluoride ion catalyst or a salt of {HEAD ~ a chiral or non chiral auxiliary} for cyclization 
{ TAIL ~ The process } employing a non chiral auxiliary in the starting material can employ either a fluoride ion catalyst or a salt of { HEAD ~ a chiral or non chiral auxiliary } for cyclization
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 HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH