Tautomerism unveils a self-inhibition mechanism of crystallization.

Modifiers are commonly used in natural, biological, and synthetic crystallization to tailor the growth of diverse materials. Here, we identify tautomers as a new class of modifiers where the dynamic interconversion between solute and its corresponding tautomer(s) produces native crystal growth inhibitors. The macroscopic and microscopic effects imposed by inhibitor-crystal interactions reveal dual mechanisms of inhibition where tautomer occlusion within crystals that leads to natural bending, tunes elastic modulus, and selectively alters the rate of crystal dissolution.

Predicting ligand removal energetics in thiolate-protected nanoclusters from molecular complexes.

Thiolate-protected metal nanoclusters (TPNCs) have attracted great interest in the last few decades due to their high stability, atomically precise structure, and compelling physicochemical properties. Among their various applications, TPNCs exhibit excellent catalytic activity for numerous reactions; however, recent work revealed that these systems must undergo partial ligand removal in order to generate active sites. Despite the importance of ligand removal in both catalysis and stability of TPNCs, the role of ligands and metal type in the process is not well understood.

Catalytic radical difluoromethoxylation of arenes and heteroarenes.

Intermolecular C-H difluoromethoxylation of (hetero)arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a redox-active difluoromethoxylating reagent and photoredox catalysts for the direct C-H difluoromethoxylation of (hetero)arenes. Our approach is operationally simple, proceeds at room temperature, and uses bench-stable reagents.

Redox-Active Reagents for Photocatalytic Generation of the OCF Radical and (Hetero)Aryl C-H Trifluoromethoxylation.

The trifluoromethoxy (OCF ) radical is of great importance in organic chemistry. Yet, the catalytic and selective generation of this radical at room temperature and pressure remains a longstanding challenge. Herein, the design and development of a redox-active cationic reagent (1) that enables the formation of the OCF radical in a controllable, selective, and catalytic fashion under visible-light photocatalytic conditions is reported.

Epimerization of Tertiary Carbon Centers via Reversible Radical Cleavage of Unactivated C(sp)-H Bonds.

Reversible cleavage of C(sp)-H bonds can enable racemization or epimerization, offering a valuable tool to edit the stereochemistry of organic compounds. While epimerization reactions operating via cleavage of acidic C(sp)-H bonds, such as the Cα-H of carbonyl compounds, have been widely used in organic synthesis and enzyme-catalyzed biosynthesis, epimerization of tertiary carbons bearing a nonacidic C(sp)-H bond is much more challenging with few practical methods available. Herein, we report the first synthetically useful protocol for the epimerization of tertiary carbons via reversible radical cleavage of unactivated C(sp)-H bonds with hypervalent iodine reagent benziodoxole azide and HO under mild conditions.

Catalytic C-H Trifluoromethoxylation of Arenes and Heteroarenes.

The intermolecular C-H trifluoromethoxylation of arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a novel trifluoromethoxylating reagent and redox-active catalysts for the direct (hetero)aryl C-H trifluoromethoxylation. Our approach is operationally simple, proceeds at room temperature, uses easy-to-handle reagents, requires only 0.

Predictive Model for Oxidative C-H Bond Functionalization Reactivity with 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone.

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a highly effective reagent for promoting C-H bond functionalization. The oxidative cleavage of benzylic and allylic C-H bonds using DDQ can be coupled with an intra- or intermolecular nucleophilic addition to generate new carbon-carbon or carbon-heteroatom bonds in a wide range of substrates. The factors that control the reactivity of these reactions are well-defined experimentally, but the mechanistic details and the role of substituents in promoting the transformations have not been firmly established.

A unified photoredox-catalysis strategy for C(sp)-H hydroxylation and amidation using hypervalent iodine.

We report a unified photoredox-catalysis strategy for both hydroxylation and amidation of tertiary and benzylic C-H bonds. Use of hydroxyl perfluorobenziodoxole (PFBl-OH) oxidant is critical for efficient tertiary C-H functionalization, likely due to the enhanced electrophilicity of the benziodoxole radical. Benzylic methylene C-H bonds can be hydroxylated or amidated using unmodified hydroxyl benziodoxole oxidant Bl-OH under similar conditions.

Correction: Photoredox-mediated Minisci C-H alkylation of -heteroarenes using boronic acids and hypervalent iodine.

[This corrects the article DOI: 10.1039/C6SC02653B.].

Mechanistic studies on intramolecular C-H trifluoromethoxylation of (hetero)arenes via OCF3-migration.

The one-pot two-step intramolecular aryl and heteroaryl C-H trifluoromethoxylation recently reported by our group has provided a general, scalable, and operationally simple approach to access a wide range of unprecedented and valuable OCF3-containing building blocks. Herein we describe our investigations to elucidate its reaction mechanism. Experimental data indicate that the O-trifluoromethylation of N-(hetero)aryl-N-hydroxylamine derivatives is a radical process, whereas the OCF3-migration step proceeds via a heterolytic cleavage of the N-OCF3 bond followed by rapid recombination of a short-lived ion pair.