| abstract |
Compounds of formula (I) or (II), wherein X represents H, C1-6 alkyl or C1-6 alkoxy, said alkyl or alkoxy being optionally substituted with one or more groups; a is 0,1,2,3 or 4; Y represents H or C1-6 alkyl; 1, 2 or 3 of the members Z of the 5-membered aromatic ring are independently selected from -O-, -S-, -N= or -NR-, where R is H or C1-6 alkyl optionally substituted with one or more of groups; and E represents a moiety such that EH is an amine; provided that in formula (I) if a = 0 then Y≠H, are provided along with a method of selecting desired protecting groups by measuring the fragmentation rates of compounds of formula (I) or (II) when the nitro group is selected. |