15 Paired Electrolysis

While paired electrochemical reactions have a history that can be traced back to the 19th century and have been very effectively used for the production of commercial products, the larger synthetic community has only recently started to embrace the opportunities this approach offers to maximize the overall energy and atom efficiency of electrochemical processes. In this review, a summary of these efforts is presented in the context of four classes of paired electrochemical reactions. These classes of reaction involve parallel processing of products at the anode and cathode, divergent reactions that use a single starting material in different ways, convergent reactions that combine products made at the anode and cathode, and sequential reactions that pass a substrate between the electrodes.

One-Pot Synthesis of 3-(1,2,3,4-Tetrahydroisoquinolin-1-yl)-isoquinolin-1(2H)-ones by Sequential DEAD-Promoted Oxidative Ugi/Wittig Reaction Starting from Phosphonium Salt Precursors

A new one-pot Synthesis of 3-(1,2,3,4-tetrahydroisoquinolin-1-yl)- isoquinolin-1(2H)-ones by DEAD-promoted oxidative Ugi/Wittig reaction was developed. The sequential reactions of (2-carboxybenzyl)triphenylphosphonium salts, isocyanides and N-aryl-1,2,3,4-tetrahydroisoquinolines produced 3-(1,2,3,4-tetrahydroisoquinolin-1-yl)- isoquinolin-1(2H)-ones in moderate to good overall yields in the presence of DEAD and Et3N.

One-pot Synthetic Approaches for the Construction of Isochroman-4-ones and Benzoxazin-3-ones Using O,P-Acetals

A method for synthesizing six-membered heterocyclic compounds was developed based on the features of O,P-acetals. Sequential reactions of intramolecular cyclization between the methylene carbon atom of O,P-acetal and its electrophilic functional group (ester or protected carbamate) was followed by Horner-Wadsworth-Emmons (HWE) olefination with various aldehydes. The developed one-pot method yielded isochroman-4-one and benzoxazin-3-one derivatives with an alkylidene moiety.

A counter-enzyme complex regulates glutamate metabolism in Bacillus subtilis

Multi-enzyme assemblies composed of metabolic enzymes catalyzing sequential reactions are being increasingly studied. Here, we report the discovery of a 1.6 megadalton multi-enzyme complex from Bacillus subtilis composed of two enzymes catalyzing opposite rather than sequential reactions (counter-enzymes): glutamate synthase (GltAB), and glutamate dehydrogenase (GudB), that make and break glutamate, respectively. In vivo and in vitro studies show that the primary role of complex formation is to inhibit GudBs activity as this enzyme is constitutively expressed including in glutamate-limiting conditions. Using cryo-electron microscopy, we elucidated the structure of the complex and the basis of GudBs inhibition. Finally, we show that this complex that exhibits unusual oscillatory progress curves is a necessity for planktonic growth in glutamate-limiting conditions, but is also essential for biofilm growth in glutamate-rich media, suggesting a regulatory role at fluctuating glutamate concentrations.

Synthesis of functionalised 2,3-dihydroquinolin-4(1H)-ones vs. quinoline or N-alkenylindole derivatives through sequential reactions of 2-alkynylanilines with ketones

The diversity-oriented synthesis of 2,2,3-substituted-2,3-dihydroquinolin-4(1H)-ones vs. functionalised quinoline or N-alkenylindole derivatives is described.