Fluorine chemistry plays an increasingly important role in pharmaceutical, agricultural, and materials industries. The incorporation of fluorine-containing groups into organic molecules can improve their chemical and physical properties, which attracts continuous interest in organic synthesis. Among various reported methods, transition-metal-catalyzed fluorination/fluoroalkylation has emerged as a powerful method for the construction of these compounds. This review attempts to describe the major advances in the transition-metal-catalyzed incorporation of fluorine, trifluoromethyl, difluoromethyl, trifluoromethylthio, and trifluoromethoxy groups reported between 2011 and 2019.
Molecular
imprinting is a powerful and yet simple method to create
multifunctional binding sites within a cross-linked polymer network.
We report a new class of synthetic glucosidase prepared through molecular
imprinting and postfunctionalization of cross-linked surfactant micelles.
These catalysts are protein-sized water-soluble nanoparticles that
can be modified in multiple ways. As their natural counterparts, they
bind a glucose-containing oligo- or polysaccharide. They contain acidic
groups near the glycosidic bond to be cleaved, with the number and
distance of the acid groups tuned systematically. Hydrolysis of cellulose
in a key step in biomass conversion but is hampered by the incalcitrance
of the highly crystalline cellulose fibers. The synthetic glucosidases
are shown to hydrolyze cellobiose and cellulose under a variety of
conditions. The best catalyst, with a biomimetic double acid catalytic
motif, can hydrolyze cellulose with one-fifth of the activity of commercial
cellulases in aqueous buffer. As a highly cross-linked polymeric nanoparticle,
the synthetic catalyst is stable at elevated temperatures in both
aqueous and nonaqueous solvents. In a polar aprotic solvent/ionic
liquid mixture, it hydrolyzes cellulose several times faster than
commercial cellulases in aqueous buffer. When deposited on magnetic
nanoparticles, it retains 75% of its activity after 10 cycles of usage.
Phosphorylation is the most common reversible post-translational modification (PTM) of proteins. Because a given kinase often has many substrates in a cell and is involved in numerous functions, traditional inhibition of the enzyme leads to unintended consequences. Here we report synthetic receptors to manipulate kinase phosphorylation precisely for the first time, utilizing the receptors' abilities to bind peptides with high affinity and specificity. The inhibition enables selective phosphorylation of peptides with identical consensus motifs in a mixture. A particular phosphosite can be inhibited while other sites in the same substrate undergo phosphorylation. The receptors may work either individually on their targeted strands or in concert to protect segments of a long sequence. The binding-derived inhibition is able to compete with protein−protein interactions within a multidomain kinase, enabling controlled PTM to be performed in a previously unavailable manner.
Synthetic glycosidases with a sugar-binding active site and a precisely positioned acidic group hydrolyze oligo- and polysaccharides selectively in hot water to afford desired sugar products in a single step.
A poor or mediocre stereoselectivity is a key roadblock for a chiral catalyst to find practical adoptions. We report a facile method to create a tunable chiral space near a chiral catalyst to augment its selectivity. The space was created rationally through templated polymerization within cross-linked micelles, using readily available amino acid derivatives. It provided gated entrance of reactants to the catalyst, enabling a mediocre prolinamide to catalyze aldol condensation in water with excellent yields and ee, in a size-and shape-selective manner.
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