For example, compounds of formula (5) wherein PG is Boc can be converted to (6) by treating with an acid such as, but not limited to, trifluoroacetic acid or hydrochloric acid.Diamines of formula (4) can be prepared using reaction conditions analogous to those as described in the specific examples herein, or in U.S. Pat. No. 6,809,105.Compounds of formula (7) wherein R1 is other than hydrogen can