Biochemical and structural characterization of a sphingomonad diarylpropane lyase for cofactorless deformylation.

Lignin valorization is being intensely pursued via tandem catalytic depolymerization and biological funneling to produce single products. In many lignin depolymerization processes, aromatic dimers and oligomers linked by carbon-carbon bonds remain intact, necessitating the development of enzymes capable of cleaving these compounds to monomers. Recently, the catabolism of -1,2-diguaiacylpropane-1,3-diol (-DGPD), a ring-opened lignin-derived β-1 dimer, was reported in .

Mixed plastics waste valorization through tandem chemical oxidation and biological funneling.

Mixed plastics waste represents an abundant and largely untapped feedstock for the production of valuable products. The chemical diversity and complexity of these materials, however, present major barriers to realizing this opportunity. In this work, we show that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion.

The Critical Role of Process Analysis in Chemical Recycling and Upcycling of Waste Plastics.

There is an urgent need for new technologies to enable circularity for synthetic polymers, spurred by the accumulation of waste plastics in landfills and the environment and the contributions of plastics manufacturing to climate change. Chemical recycling is a promising means to convert waste plastics into molecular intermediates that can be remanufactured into new products. Given the growing interest in the development of new chemical recycling approaches, it is critical to evaluate the economics, energy use, greenhouse gas emissions, and other life cycle inventory metrics for emerging processes,relative to the incumbent, linear manufacturing practices employed today.

Photoredox-Catalyzed Synthesis of α-Amino Acid Amides by Imine Carbamoylation.

An operationally simple protocol for the photocatalytic carbamoylation of imines is reported. Easily available, bench-stable 4-amido Hantzsch ester derivatives serve as precursors to carbamoyl radicals that undergo rapid addition to -aryl imines. The reaction proceeds under blue light irradiation in the presence of the photocatalyst 3DPAFIPN and Brønsted/Lewis acid additives.

Photoredox-Catalyzed Addition of Carbamoyl Radicals to Olefins: A 1,4-Dihydropyridine Approach.

Functionalization with C1-building blocks are key synthetic methods in organic synthesis. The low reactivity of the most abundant C -molecule, carbon dioxide, makes alternative carboxylation reactions with CO -surrogates especially important. We report a photoredox-catalyzed protocol for alkene carbamoylations.

Catalyst-Free -Deoxygenation by Photoexcitation of Hantzsch Ester.

A mild and operationally simple protocol for the deoxygenation of a variety of heteroaryl -oxides and nitroarenes has been developed. A mixture of substrate and Hantzsch ester is proposed to result in an electron donor-acceptor complex, which upon blue-light irradiation undergoes photoinduced electron transfer between the two reactants to afford the products. -oxide deoxygenation is demonstrated with 22 examples of functionally diverse substrates, and the chemoselective reduction of nitroarenes to the corresponding hydroxylamines is also shown.

Synthesis of substituted -styrenes by Hiyama-type coupling of oxasilacycloalkenes: application to the synthesis of a 1-benzoxocane.

Several Hiyama cross-coupling reactions of oxasilacycloalkenes and aryl iodides are described that produce trisubstituted -styrenes in moderate to excellent yields. Both electron-rich and electron-poor aryl iodides are tolerated in the cross-coupling reaction. The oxasilacycloalkene coupling partners were prepared by ruthenium-catalyzed intramolecular anti-hydrosilylation of alkynols.

Decarboxylative Alkyl-Alkyl Cross-Coupling Reactions.

Alkyl with alkyl: A significant development in alkyl-alkyl cross-coupling reactions, namely the nickel-catalyzed decarboxylative Negishi coupling of N-hydroxyphthalimide esters, was recently reported by Baran and co-workers. This method enables the synthesis of various highly functionalized compounds, including natural product derivatives.

Intra- and Intermolecular Nickel-Catalyzed Reductive Cross-Electrophile Coupling Reactions of Benzylic Esters with Aryl Halides.

Nickel-catalyzed cross-electrophile coupling reactions of benzylic esters and aryl halides have been developed. Both inter- and intramolecular variants proceed under mild reaction conditions. A range of heterocycles and functional groups are tolerated under the reaction conditions.

Enantiospecific intramolecular Heck reactions of secondary benzylic ethers.

Enantioenriched methylenecyclopentanes are synthesized by stereospecific, nickel-catalyzed Heck cyclizations of secondary benzylic ethers. The reaction proceeds in high yield and enantiospecificity for benzylic ethers of both π-extended and simple arenes. Ethers with pendant 1,2-disubstituted olefins form trisubstituted olefins with control of both absolute configuration and alkene geometry.