B?H,C?H,and B?C Bond Activation: The Role of Two Adjacent Agostic Interactions

Tuning the nature of the linker in a L∼BHR phosphinoborane compound led to the isolation of a ruthenium complex stabilized by two adjacent, δ‐C H and ε‐B_sp2 H, agostic interactions. Such a unique coordination mode stabilizes a 14‐electron “RuH₂P₂” fragment through connected σ‐bonds of different polarity, and affords selective B H, C H, and B C bond activation as illustrated by reactivity studies with H₂ and boranes.     

The Oxidative Mechanism in Electrophilic C?H Activation: The Case of CH2F2 and CH2Cl2

The H^.‐atom transfer (HAT) reaction is investigated in the gas phase, starting from two different entrance channels, O₂^.+/CH₂X₂ and CH₂X₂^.+/O₂ (X=F, Cl), that correspond to a step of hydride transfer and to HAT, respectively. Analysis of the spin and charge along the reaction pathway shows that HAT occurs through the same reacting configuration, irrespective of whether the reactants are formed within the complex or are free isolated species.     

The Chemistry of C?H Bond Activation on Diamond

The surface of hydrogen‐terminated diamond resembles a solid hydrocarbon substrate. Interestingly, the C? H bonds on the diamond surface are not as unreactive as that of saturated hydrocarbon molecules owing to its unique surface electronic properties. The invention of C? H bond activation and C? C coupling reactions on the diamond surface allows chemists to develop powerful chemical transistors, biosensors, and photovoltaic cells on the diamond platform.     

Mixed (PS/PO)‐Stabilized Geminal Dianion: Facile Diastereoselective Intramolecular C?H Activations by a Related Ruthenium–Carbene Complex

A new unsymmetrical geminal dianion that contained both a phosphine oxide moiety and a phosphine sulfide moiety has been synthesized. Its reactivity towards Ru^II was explored, which led to the formation of a highly reactive carbene complex that evolved at room temperature to yield a kinetic orthometalated Ru^II complex through C? H activation of the phenyl group of the phosphine oxide moiety. This insertion was found to be thermally reversible and a second C? H insertion occurred at a phenyl group of the phosphine sulfide moiety to form the thermodynamic orthometalated Ru^II complex in a diastereospecific manner. DFT calculations fully rationalized the experimental findings in terms of the relative energies of the kinetic and thermodynamic products and allowed the mechanism of this process to be fully understood.     

Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of N?H Imines and Alkynes by C?H/N?H Activation

Described herein is a manganese‐catalyzed dehydrogenative [4+2] annulation of N H imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation represents the first example of manganese‐catalyzed C H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H₂ as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed C H activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle.     

Fluorsulfonylmethylidene sulfur difluoride oxide,FSO2?CH  SF2  O

SO₃ adds across the CS double bond of H₂C  SF₄ with formation of 2-tetrafluoro-4-dioxo-1,2,4-oxadithietane, which rearranges to fluorsulfonylmethylidene sulfur difluoride oxide, F SO₂ CH  SF₂  O in the presence of CsF. © John Wiley & Sons, Inc.     

The ?NH?(C)?Br functionality of heteroaromatic compounds as a synthon for fused dihydrooxazoles

Fused dihydrooxazoles are produced by the reaction of 8‐bromoteophylline (1), 6‐bromo‐2‐pyridone (7), or 2‐bromobenzimidazole (11) with an N‐substituted N‐(2,3‐epoxypropyl)amine. The product derived from 1 undergoes rearrangement to a fused dihydrooxazine while the fused dihydrooxazoles derived from 7 and 11 are stable. J. Heterocyclic Chem., (2011).     

The Redox‐Neutral Approach to C?H Functionalization

The direct functionalization of C? H bonds is an attractive strategy in organic synthesis. Although several advances have been made in this area, the selective activation of inert sp³ C? H bonds remains a daunting challenge. Recently, a new type of sp³ C? H activation mode through internal hydride transfer has demonstrated the potential to activate remote sp³ C? H linkages in an atom‐economic manner. This Minireview attempts to classify recent advances in this area including the transition to non‐activated sp³ C? H bonds and asymmetric hydride transfers.