Cell-Free Multistep Gene Regulatory Cascades Using Eukaryotic ON-Riboswitches Responsive to Expressed Protein Ligands.

One of the most pressing challenges in cell-free synthetic biology is to assemble well-controlled genetic circuits. However, no complex circuits have been reported in eukaryotic cell-free systems, unlike the case in bacterial ones, despite several unique advantages of the former. We here developed protein-responsive upregulating riboswitches (ON-riboswitches) that function in wheat germ extract to create multistep gene regulatory cascades.

Nickel/Photoredox Dual-Catalyzed Conversion of Allyl Esters to Ketones via the Formal Deletion of Oxygen.

We report herein the catalytic conversion of allylic esters into the corresponding ketones by the formal deletion of an oxygen atom. The key to the success of the reaction is the dual use of nickel and photoredox catalysts; the former mediates C-O bond activation and C-C bond formation, while the latter is responsible for deoxygenation of the acyloxy group using PPh as a stoichiometric reductant. Catalytic replacement of an oxygen atom of an allyl ester with a tethered alkene is also accomplished.

Palladium-Catalyzed Unimolecular Fragment Coupling of -Allylamides via Elimination of Isocyanate.

Transition metal-catalyzed unimolecular fragment coupling (UFC) is defined as processes that forge new chemical bonds through the extrusion of molecules, such as CO and CO, and the subsequent recombination of the remaining fragments. Herein, we report on a new UFC reaction that involves the palladium-catalyzed elimination of an isocyanate fragment from an amide, with the formation of carbon-carbon and carbon-heteroatom bonds. An organometallic intermediate that is relevant to the catalytic reaction was characterized by X-ray crystallography.