Adding value to organic synthesis. Novel imine reductases enable the enantioselective reduction of imines to afford chiral amines. Likewise, novel bioinspired artificial metalloenzymes can perform the same reaction as well. Remarkable recent examples are herein discussed.

Lipase-catalyzed transesterification was used as an efficient tool for the interconversion of β-ketoesters. Catalytic activity of commercial lipase B from Candida antarctica (Novozym 435) was evaluated in systems involving non activated acyl donors, and enhanced using microwave irradiation. Interestingly, the combination of CAL B in microwave irradiation worked excellent in solvent-free conditions, thus assuring a highly competitive and environment-friendly process with high yields (up to 96%) in competitive times (< 2h). The combination of biocatalysis with solvent-free systems and microwave assistance is currently scarcely used, and may represent a powerful synergy for preparative reactions.

With the objective to develop a potential ^99mTc radiopharmaceutical for imaging the androgen receptor (AR) in prostate cancer, four ligands bearing the same pharmacophore derived from the AR antagonist flutamide were prepared, labeled with ^99mTc, and their structures corroborated via comparison with the corresponding stable rhenium analogs. All complexes were obtained with high radiochemical purity. Three of the complexes were highly stable, and, due to their favorable physicochemical properties, were further evaluated using AR-positive and AR-negative cells in culture. All complexes exhibited considerable uptake in AR-positive cells, which could be blocked by an excess of flutamide. The efflux from the cells was moderate. They also showed significantly lower uptakes in AR-negative cells, indicating interactions with the AR receptor. However, the binding affinities were considerably reduced by the coordination to ^99mTc, and the complex that exhibited the best biological behavior did not show sufficient specificity towards AR-positive cells.

Stereoselective preparations of protected rare sugars and derivatives, namely l-psicose, l-altritol, and l-talose have been achieved in 70, 44, and 18% yield, respectively, from an orthogonally protected l-glyceraldehyde derivative. The key step is the stereoselective proline-catalyzed aldol reaction of this aldehyde with dioxanone.