Development and Characterization of Novel and Selective Inhibitors of Cytochrome P450 CYP26A1, the Human Liver Retinoic Acid Hydroxylase.

Cytochrome P450 CYP26 enzymes are responsible for all-trans-retinoic acid (atRA) clearance. Inhibition of CYP26 enzymes will increase endogenous atRA concentrations and is an attractive therapeutic target. However, the selectivity and potency of the existing atRA metabolism inhibitors toward CYP26A1 and CYP26B1 is unknown, and no selective CYP26A1 or CYP26B1 inhibitors have been developed.

Novel di-aryl-substituted isoxazoles act as noncompetitive inhibitors of the system Xc(-) cystine/glutamate exchanger.

The system xc(-) antiporter is a plasma membrane transporter that mediates the exchange of extracellular l-cystine with intracellular l-glutamate. This exchange is significant within the context of the CNS because the import of l-cystine is required for the synthesis of the antioxidant glutathione, while the efflux of l-glutamate has the potential to contribute to either excitatory signaling or excitotoxic pathology. Changes in the activity of the transport system have been linked to the underlying pathological mechanisms of a variety of CNS disorders, one of the most prominent of which is its highly enriched expression in glial brain tumors.

Synthesis of new quinolinequinone derivatives and preliminary exploration of their cytotoxic properties.

A series of 7-amino- and 7-acetamidoquinoline-5,8-diones with aryl substituents at the 2-position were synthesized, characterized, and evaluated as potential NAD(P)H:quinone oxidoreductase (NQO1) -directed antitumor agents. The synthesis of lavendamycin analogues is illustrated. Metabolism studies demonstrated that 7-amino analogues were generally better substrates for NQO1 than 7-amido analogues, as were compounds with smaller heteroaromatic substituents at the C-2 position.

Suzuki-Miyaura Cross-Coupling of Benzylic Bromides Under Microwave Conditions.

A procedure for benzylic Suzuki-Miyaura cross-coupling under microwave conditions has been developed. These conditions allowed for heterocyclic compounds to be coupled. Optimum conditions found were Pd(OAc)(2), JohnPhos as the catalyst and ligand, potassium carbonate as base, and DMF as the solvent.

Asymmetric [C + NC + CC] coupling entry to the naphthyridinomycin natural product family: formal total synthesis of cyanocycline A and bioxalomycin β2.

A full account of our [C + NC + CC] coupling approach to the naphthyridinomycin family of natural products is presented, culminating in formal total syntheses of cyanocycline A and bioxalomycin β2. The key complexity-building reaction in the synthesis involves the Ag(I)-catalyzed endo-selective [C + NC + CC] coupling of aldehyde 7, (S)-glycyl sultam 8, and methyl acrylate (9) to provide the highly functionalized pyrrolidine 6, which was carried forward to an advanced intermediate (compound 33) in Fukuyama's synthesis of cyanocycline A. Since cyanocycline A has been converted to bioxalomycin β2, this constitutes a formal synthesis of the latter natural product as well.