Click-like condensation of boronic acids with specifically designed triols (boronate-triol coupling) produces stable diamantane adducts in aqueous medium, which can be controllably cleaved to initial components under acidic conditions or by using boric acid as a chemical trigger. This novel "click-declick" strategy allows for the creation of temporary covalent connections between two or more modular units, which was demonstrated by the synthesis of new fluorophore-labeled natural molecules (peptides, steroids), supramolecular assemblies, modified polymers, boronic acid scavengers, solid-supported organocatalysts, biodegradable COF-like materials, and dynamic combinatorial libraries.
Acylation of nitronates affords α-acyloxyoxime derivatives via an umpolung functionalization of the α-position. This transformation involves generation of hitherto unknown N-acyloxy, N-oxyenamines and their fast [3,3]-sigmatropic rearrangement driven by the cleavage of the weak N-O bond. The reaction has a broad scope, and it is regioselective in the case of nitronates possessing nonsymmetrically substituted α-positions. Application to the formal total synthesis of clausenamide and cis-clausenamide is presented.
What is the most significant result of this study? Non-alkali metal azides are explosive compounds, which can hardly be considered as convenient and useful reagents in organic synthesis. However,a sw ed iscovered in our study the metal ion can modulate the reactivity of the azide anion thus opening new opportunities for the synthesis of organic azides. The compromise is that the use of af ree-metal azide is not needed, since it can be safely generated in solution by ion exchange from NaN 3 and the corresponding metal salt. What was the inspiration for this cover design? The inspiration for the cover picture came from cue sports. We make an analogy of the chemical behavior observed in our studies with ab illiard game, in which balls are ions, and pockets are reac-tive centers of an organic molecule. Unlike in ar eal game based on mechanics, in a" chemical billiard", ion balls after collision may not only bounce off each other,b ut also can fuse to form ac ova-lently bonded pair,w hich moves along its own trajectory.A "metal-ion ball" depending on its nature, directs the attack of the "azide-anion ball" on either one or another electrophilic "pocket" of the substrate (silicon or carbon atoms). Thus, ac hemist is like ap rofessional billiard player selecting the right ball (promoter/cat-alyst) and disposition (reaction conditions) to hit the target center in the molecule. This simple allegory illustrates the results described in our article in ap opular and easy-to-understand manner. What other topics are you working on at the moment? Although we are originally synthetic chemists, our research interests go far beyond the borders of traditional synthesis. Besides our focus on NÀOs ystems and stereoselective synthesis, we are working in the areas of medicinal chemistry,c lick reactions, coordination compounds, polymers and quantum-chemical calculations. Our particular passions are adamantane-like molecules. Among our recent achievements are the synthesis and structural studies of "isourotropine" (the isomer of methenamine) and B,O,N-doped adamantanes. Invited for the cover of this issue is the group of Alexey Sukhorukov at the N. D. ZelinskyI nstitute of Organic Chemistry. The image depicts the reaction pathways taken by metal azides as a" chemical billiard"g ame. Read the full text of the arti
Condensation of oximes with boronic acids RB(OH)2 or B(OH)3 affords remarkably stable 2,4,10-trioxa-1,5,7-triaza-3-boroadamantanes via an unprecedented multicomponent process. The mechanism involves the reversible generation of unstable oxime cyclotrimers, which are readily intercepted by boronic acids.
An efficient synthesis of 4,7‐dibromo[1,2,5]thiadiazolo[3,4‐d]pyridazine is reported. For the first time, palladium‐catalysed cross‐coupling reactions of a dihalo derivative was found to be a powerful tool for the selective formation of various mono‐ and diarylated derivatives of strongly electron‐accepting heterocycles. Suzuki–Miyaura coupling can be successfully employed for the preparation of mono‐arylated derivatives, whereas Stille coupling is useful for both mono‐ and diaryl(hetaryl)ated heterocycles. The cyclic voltammogram showed that 4,7‐dibromo[1,2,5]thiadiazolo[3,4‐d]pyridazine can be easily oxidized to form a stable anion radical. The calculated values of ELUMO confirmed that [1,2,5]thiadiazolo[3,4‐d]pyridazine is one of the strongest electron–acceptor systems.
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