Hydrogenation of esters is vital to the chemical industry for the production of alcohols, especially fatty alcohols that find broad applications in consumer products. Current technologies for ester hydrogenation rely on either heterogeneous catalysts operating under extreme temperatures and pressures or homogeneous catalysts containing precious metals such as ruthenium and osmium. Here, we report the hydrogenation of esters under relatively mild conditions by employing an iron-based catalyst bearing a PNP-pincer ligand. This catalytic system is also effective for the conversion of coconut oil derived fatty acid methyl esters to detergent alcohols without adding any solvent.

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A series of ruthenium- and iron-based pincer catalysts have been tested for the homogeneous hydrogenation of fatty acid methyl esters to fatty alcohols with turnover numbers (TONs) of up to 1860. These catalysts operate under neat conditions (no solvent) from the gram to the kilogram scale. The required temperature (135 °C) and H2 pressure (300–1000 psig) are much lower than those needed for current industrial processes, which rely on heterogeneous copper chromite catalysts. The fatty alcohol products can be purified through distillation, resulting in low levels of Ru (1 ppm) and P (<25 ppm). The five-coordinate Milstein catalyst and Takasago’s borane-stabilized catalyst are also effective for the direct hydrogenation of coconut oil to fatty alcohols. These results hold the promise of using homogeneous catalysts for ester hydrogenation in an industrial setting.

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In this article we describe the application of structural biology methods to the discovery of novel potent inhibitors of methionine aminopeptidases. These enzymes are employed by the cells to cleave the N-terminal methionine from nascent peptides and proteins. As this is one of the critical steps in protein maturation, it is very likely that inhibitors of these enzymes may prove useful as novel antibacterial agents. Involvement of crystallography at the very early stages of the inhibitor design process resulted in serendipitous discovery of a new inhibitor class, the pyrazole-diamines. Atomic-resolution structures of several inhibitors bound to the enzyme illuminate a new mode of inhibitor binding.