An sp 2 /sp 3 get‐together : A novel and efficient method can be used to synthesize 3,3‐disubstitued oxindoles by the direct intramolecular oxidative coupling of an aryl C? H and a C? H center (see scheme; DMF=N,N‐dimethylformamide).
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‐Bsp2 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. 相似文献
The transformation of C? H bonds into other chemical bonds is of great significance in synthetic chemistry. C? H bond‐activation processes provide a straightforward and atom‐economic strategy for the construction of complex structures; as such, they have attracted widespread interest over the past decade. As a prevalent directing group in the field of C? H activation, the amide group not only offers excellent regiodirecting ability, but is also a potential C? N bond precursor. As a consequence, a variety of nitrogen‐containing heterocycles have been obtained by using these reactions. This Focus Review addresses the recent research into the amide‐directed tandem C? C/C? N bond‐formation process through C? H activation. The large body of research in this field over the past three years has established it as one of the most‐important topics in organic chemistry. 相似文献
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. 相似文献
A simple method to convert readily available carboxylic acids into sulfinate salts by employing an interrupted Barton decarboxylation reaction is reported. A medicinally oriented panel of ten new sulfinate reagents was created using this method, including a key trifluoromethylcyclopropanation reagent, TFCS‐Na. The reactivity of six of these salts towards C H functionalization was field‐tested using several different classes of heterocycles. 相似文献
The organometallic approach is one of the most active topics in catalysis. The application of NH functionality in organometallic catalysis has become an important and attractive concept in catalyst design. NH moieties in the modifiers of organometallic catalysts have been shown to have various beneficial functions in catalysis by molecular recognition through hydrogen bonding to give catalyst–substrate, ligand–ligand, ligand–catalyst, and catalyst–catalyst interactions. This Review summarizes recent progress in the development of the organometallic catalysts based on the concept of cooperative catalysis by focusing on the NH moiety. 相似文献
Copper‐catalyzed Ullmann condensations are key reactions for the formation of carbon–heteroatom and carbon–carbon bonds in organic synthesis. These reactions can lead to structural moieties that are prevalent in building blocks of active molecules in the life sciences and in many material precursors. An increasing number of publications have appeared concerning Ullmann‐type intermolecular reactions for the coupling of aryl and vinyl halides with N, O, and C nucleophiles, and this Minireview highlights recent and major developments in this topic since 2004. 相似文献
In hydrogen‐metal‐phosphorus (H M P) transition metal complexes (proposed as intermediates of H P bond addition to alkynes in the catalytic hydrophosphorylation, hydrophosphinylation, and hydrophospination reactions), alkyne insertion into the metal‐hydrogen bond was found much more facile compared to alkyne insertion into the metal‐phosphorus bond. The conclusion was verified for different metals (Pd, Ni, Pt, and Rh), ligands, and phosphorus groups at various theory levels (B3LYP, B3PW91, BLYP, MP2, and ONIOM). The relative reactivity of the metal complexes in the reaction with alkynes was estimated and decreased in the order of Ni>Pd>Rh>Pt. A trend in relative reactivity was established for various types of phosphorus groups: PR2>P(O)R2>P(O)(OR)2, which showed a decrease in rate upon increasing the number of the oxygen atoms attached to the phosphorus center. 相似文献
Electroactive fused ethylenedithio? tetrathiafulvalene? [4]helicene and ‐[6]helicenes have been synthesized through a strategy that involved the preparation of 2,3‐dibromo‐helicene derivatives as intermediates. The dihedral angles between the terminal helicenes, as determined by single‐crystal X‐ray analysis, are 22.7° and 50.7° for the [4]helicene and [6]helicene, respectively. Their solid‐state architectures show interplay between S???S and π???π intermolecular interactions. The chiroptical properties of the enantiopure EDT? TTF? [6]helicene derivatives have been investigated and supported by TDDFT calculations. Remarkable redox switching of the circular dichroism (CD) signal between the neutral and radical‐cation species has been achieved. 相似文献
A “niche” topic in the past decade, the asymmetric C? H bond activation has been attracting growing interest over the last few years. Particularly significant advances have been achieved in the field of direct, stereoselective transformations of C(sp2)? H bonds. This Concept article intends to showcase different types of asymmetric C(sp2)? H bond activation reactions, emphasising both the nature of the stereo‐discriminating step and the variability of valuable scaffolds that could be rapidly constructed by means of such strategies. 相似文献
The impact of redox non‐innocence (RNI) on chemical reactivity is a forefront theme in coordination chemistry. A diamide diimine ligand, [{‐CHN(1,2‐C6H4)NH(2,6‐iPr2C6H3)}2]n (n=0 to −4), (dadi)n, chelates Cr and Fe to give [(dadi)M] ([ 1 Cr(thf)] and [ 1 Fe]). Calculations show [ 1 Cr(thf)] (and [ 1 Cr]) to have a d4 Cr configuration antiferromagnetically coupled to (dadi)2−*, and [ 1 Fe] to be S=2. Treatment with RN3 provides products where RN is formally inserted into the C C bond of the diimine or into a C H bond of the diimine. Calculations on the process support a mechanism in which a transient imide (imidyl) aziridinates the diimine, which subsequently ring opens. 相似文献
Attachment of one electron to 1,2-diBeX-benzene and 1,2-diZnX-benzene derivatives leads to the formation of stronger Be Be and Zn Zn interaction compared to the neutral one. This is reflected in the dramatic shortening of the Be Be and Zn Zn distance. The formation of these 2-center-1-electron bonds have also been confirmed by topological survey of electron density using quantum theory of atoms in molecules and electron localization function. The formation of these bonds is expected to render stability to these radical anions. These radical anions are stable toward electron detachment and computed bond dissociation energy values are also significant. 相似文献