A process for preparing and purifying a compound of Formula I is provided: or a salt thereof, wherein the subscript m is an integer of from 0 to 3; each Ra is independently selected from the group consisting of (C3-C8)cycloalkyl, (C1-C4)haloalkyl, halogen, —OH, —OR1, —SH, —SR1, —S(O)R1, —S(O)2R1, —SO2NH2, —C(O)NH2, —C(O)NHR1, —C(O)N(R1)2, —C(O)R1, —C(O)H, —CO2R1, —NO2, —NH2, —NHR1, —N(R1)2, wherein each R1 is independently (C1-C8)alkyl; L is a linking group selected from the group consisting of a bond or CH2; Qa, Qb, and Qc are each members independently selected from the group consisting of N, S, O and C(Rq) wherein each Rq is independently selected from the group consisting of H, C1-8 alkyl, halo and phenyl, and the ring having Qa, Qb, Qc and Y as ring vertices is a five-membered ring having two double bonds; and Y is selected from the group consisting of C and N.