The safener fenclorim (4,6-dichloro-2-phenylpyrimidine) increases tolerance to chloroacetanilide herbicides in rice by enhancing the expression of detoxifying glutathione S-transferases (GSTs). Fenclorim also enhances GSTs in Arabidopsis thaliana, and while investigating the functional significance of this induction in suspension cultures, we determined that these enzymes glutathionylated the safener. The resulting S-(fenclorim)-glutathione conjugate was sequentially processed to S-(fenclorim)-␥-glutamyl-cysteine and S-(fenclorim)-cysteine (FC), the latter accumulating in both the cells and the medium. FC was then either catabolized to 4-chloro-6-(methylthio)-phenylpyrimidine (CMTP) or N-acylated with malonic acid. These cysteine derivatives had distinct fates, with the enzymes responsible for their formation being induced by fenclorim and FC. Fenclorim-N-malonylcysteine was formed from FC by the action of a malonyl-CoA-dependent N-malonyltransferase. A small proportion of the fenclorim-N-malonylcysteine then underwent decarboxylation to yield a putative S-fenclorim-Nacetylcysteine intermediate, which underwent a second round of GST-mediated S-glutathionylation and subsequent proteolytic processing. The formation of CMTP was catalyzed by the concerted action of a cysteine conjugate ␤-lyase and an S-methyltransferase, with the two activities being coordinately regulated. Although the fenclorim conjugates tested showed little GST-inducing activity in Arabidopsis, the formation of CMTP resulted in metabolic reactivation, with the product showing good enhancing activity. In addition, CMTP induced GSTs and herbicide-safening activity in rice. The bioactivated CMTP was in turn glutathione-conjugated and processed to a malonyl cysteine derivative. These results reveal the surprisingly complex set of competing catabolic reactions acting on xenobiotics entering the S-glutathionylation pathway in plants, which can result in both detoxification and bioactivation.

Recently, the aminoquinazoline motif has been highly prevalent in anticancer pharmaceutical compounds. Synthetic methods are required to make this structure on a multikilo scale and in high purity. The initial route to aminoquinazoline AZD8931 suffered from the formation of late-stage impurities. To avoid these impurities, a new high-yielding Dimroth rearrangement approach to the aminoquinazoline core of AZD8931 was developed. Assessment of route options on a gram scale demonstrated that the Dimroth rearrangement is a viable approach. The processes were then evolved for large-scale production with learning from a kilo campaign and two plant-scale manufactures. Identification of key process impurities offers an insight into the mechanisms of the Dimroth rearrangement as well as the hydrogenation of a key intermediate. The final processes were operated on a 30 kg scale delivering the target AZD8931 in 41% overall yield.

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