Decarboxylative C?H functionalization reactions are highly attractive methods for forging carbon–carbon bonds considering their inherent step‐ and atom‐economical features and the pervasiveness of carboxylic acids and C?H bonds. An ideal approach to achieve these dehydrogenative transformations is through hydrogen evolution without using any chemical oxidants. However, effective couplings by decarboxylative carbon–carbon bond formation with proton reduction remain an unsolved challenge. Herein, we report an electrophotocatalytic approach that merges organic electrochemistry with photocatalysis to achieve the efficient direct decarboxylative C?H alkylation and carbamoylation of heteroaromatic compounds through hydrogen evolution. This electrophotocatalytic method, which combines the high efficiency and selectivity of photocatalysis in promoting decarboxylation with the superiority of electrochemistry in effecting proton reduction, enables the efficient coupling of a wide range of heteroaromatic bases with a variety of carboxylic acids and oxamic acids. Advantageously, this method is scalable to decagram amounts, and applicable to the late‐stage functionalization of drug molecules. 相似文献
A quinoline‐based ligand effectively promotes the palladium‐catalyzed borylation of C(sp3)? H bonds. Primary β‐C(sp3)? H bonds in carboxylic acid derivatives as well as secondary C(sp3)? H bonds in a variety of carbocyclic rings, including cyclopropanes, cyclobutanes, cyclopentanes, cyclohexanes, and cycloheptanes, can thus be borylated. This directed borylation method complements existing iridium(I)‐ and rhodium(I)‐catalyzed C? H borylation reactions in terms of scope and operational conditions. 相似文献
The functionalization of C(sp3)?H bonds streamlines chemical synthesis by allowing the use of simple molecules and providing novel synthetic disconnections. Intensive recent efforts in the development of new reactions based on C?H functionalization have led to its wider adoption across a range of research areas. This Review discusses the strengths and weaknesses of three main approaches: transition‐metal‐catalyzed C?H activation, 1,n‐hydrogen atom transfer, and transition‐metal‐catalyzed carbene/nitrene transfer, for the directed functionalization of unactivated C(sp3)?H bonds. For each strategy, the scope, the reactivity of different C?H bonds, the position of the reacting C?H bonds relative to the directing group, and stereochemical outcomes are illustrated with examples in the literature. The aim of this Review is to provide guidance for the use of C?H functionalization reactions and inspire future research in this area. 相似文献
The intramolecular dehydrogenative amidation of aliphatic amides, directed by a bidentate ligand, was developed using a copper‐catalyzed sp3 C? H bond functionalization process. The reaction favors predominantly the C? H bonds of β‐methyl groups over the unactivated methylene C? H bonds. Moreover, a preference for activating sp3 C? H bonds of β‐methyl groups, via a five‐membered ring intermediate, over the aromatic sp2 C? H bonds was also observed in the cyclometalation step. Additionally, sp3 C? H bonds of unactivated secondary sp3 C? H bonds could be functionalized by favoring the ring carbon atoms over the linear carbon atoms. 相似文献
C?C bond formation is the most fundamental way for the chain propagation in organic molecules. This achievement through tandem oxidation of two different C?H bonds represents the state of the art in organic synthesis. Selective functionalization of the ubiquitous aliphatic C?H bonds offers an attractive option for this oxidative cross‐coupling methodology. To develop such a methodology under mild and “metal‐free” conditions remains challenging. Herein, we report hypervalent iodine‐mediated selective oxidative functionalization of aliphatic C?H bonds of alkanes with chromones and (thio)chromones. A wide range of alkanes, both cyclic and acyclic, has been found to react selectively and predictably in good yields. The developed methodology is also the first report of a direct oxidative functionalization of the C‐2 position of (thio)chromones with alkanes to access bioactive compounds. 相似文献
Mild conditions are reported for the hydroxylation of aliphatic C? H bonds through radical translocation, oxidation to carbocation, and nucleophilic trapping with H2O. This remote functionalization employs fac‐[Ir(ppy)3] together with Tzo sulfonate esters and sulfonamides to facilitate the site‐selective replacement of relatively inert C? H bonds with the more synthetically useful C? OH group. The hydroxylation of a range of substrates and the methoxylation of two substrates through 1,6‐ and 1,7‐hydrogen‐atom transfer are demonstrated. In addition, a synthesis of the antidepressant fluoxetine using remote hydroxylation as a key step is presented. 相似文献
Catalytic enantioselective directed methylene C(sp3)?H amidation reactions of 8‐alkylquinolines using a Cp*RhIII/chiral carboxylic acid (CCA) hybrid catalytic system are described. A binaphthyl‐based chiral carboxylic acid efficiently differentiates between the enantiotopic methylene C?H bonds, which leads to the formation of C?N bonds with good enantioselectivity. 相似文献
Cyclopropanes fused to pyrrolidines are important structural features found in a number of marketed drugs and development candidates. Typically, their synthesis involves the cyclopropanation of a dihydropyrrole precursor. Reported herein is a complementary approach which employs a palladium(0)‐catalyzed C? H functionalization of an achiral cyclopropane to close the pyrrolidine ring in an enantioselective manner. In contrast to aryl–aryl couplings, palladium(0)‐catalyzed C? H functionalizations involving the formation of C(sp3)? C(sp3) bonds of saturated heterocycles are very scarce. The presented strategy yields cyclopropane‐fused γ‐lactams from chloroacetamide substrates. A bulky Taddol phosphonite ligand in combination with adamantane‐1‐carboxylic acid as a cocatalyst provides the γ‐lactams in excellent yields and enantioselectivities. 相似文献
The site‐selective acyloxylation of aliphatic amides was achieved via a copper‐promoted C(sp3)? H bond functionalization process directed by a bidentate ligand. The reaction showed a great preference for activating C? H bonds of β‐methyl groups over those of γ‐methyl and unactivated methylene groups. 相似文献
Visible‐light photoredox catalysis has been successfully used in the functionalization of inert C?H bonds including C(sp2)‐H bonds of arenes and C(sp3)‐H bonds of aliphatic compounds over the past decade. These transformations are typically promoted by the process of single‐electron‐transfer (SET) between substrates and photo‐excited photocatalyst upon visible light irradiation (household bulbs or LEDs). Compared with other synthetic strategies, such as the transition‐metal catalysis and traditional radical reactions, visible‐light photoredox approach has distinct advantages in terms of operational simplicity and practicability. Versatile direct functionalization of inert C(sp2)‐H and C(sp3)‐H bonds including alkylation, trifluoromethylation, arylation and amidation, has been achieved using this practical strategy. 相似文献
Intramolecular dehydrogenative cyclization of aliphatic amides was achieved on unactivated sp3 carbon atoms by a nickel‐catalyzed C?H bond functionalization process with the assistance of a bidentate directing group. The reaction favors the C?H bonds of β‐methyl groups over the γ‐methyl or β‐methylene groups. Additionally, a predominant preference for the β‐methyl C?H bonds over the aromatic sp2 C?H bonds was observed. Moreover, this process also allows for the effective functionalization of benzylic secondary sp3 C?H bonds. 相似文献
The use of enaminones as effective synthons for a directed C?H functionalization is reported. Proof‐of‐concept protocols have been developed for the RhIII‐catalyzed synthesis of naphthalenes, based on the coupling of enaminones with either alkynes or α‐diazo‐β‐ketoesters. Two inherently reactive functionalities (hydroxy and aldehyde groups) are integrated into the newly formed cyclic framework and a broad range of substituents are tolerated, rendering target products readily available for further elaboration. 相似文献
β‐Lactams are very important structural motifs because of their broad biological activities as well as their propensity to engage in ring‐opening reactions. Transition‐metal‐catalyzed C? H functionalizations have emerged as strategy enabling yet uncommon highly efficient disconnections. In contrast to the significant progress of Pd0‐catalyzed C? H functionalization for aryl–aryl couplings, related reactions involving the formation of saturated C(sp3)? C(sp3) bonds are elusive. Reported here is an asymmetric C? H functionalization approach to β‐lactams using readily accessible chloroacetamide substrates. Important aspects of this transformation are challenging C(sp3)? C(sp3) and strain‐building reductive eliminations to for the four‐membered ring. In general, the β‐lactams are formed in excellent yields and enantioselectivities using a bulky taddol phosphoramidite ligand in combination with adamantyl carboxylic acid as cocatalyst. 相似文献
A quinoline‐based ligand effectively promotes the palladium‐catalyzed borylation of C(sp3) H bonds. Primary β‐C(sp3) H bonds in carboxylic acid derivatives as well as secondary C(sp3) H bonds in a variety of carbocyclic rings, including cyclopropanes, cyclobutanes, cyclopentanes, cyclohexanes, and cycloheptanes, can thus be borylated. This directed borylation method complements existing iridium(I)‐ and rhodium(I)‐catalyzed C H borylation reactions in terms of scope and operational conditions. 相似文献
The first examples of the direct functionalization of non‐activated aryl sp2 C?H bonds with ethyl diazoacetate (N2CHCO2Et) catalyzed by Mn‐ or Fe‐based complexes in a completely selective manner are reported, with no formation of the frequently observed cycloheptatriene derivatives through competing Buchner reaction. The best catalysts are FeII or MnII complexes bearing the tetradentate pytacn ligand (pytacn= 1‐(2‐pyridylmethyl)‐4,7‐dimethyl‐1,4,7‐triazacyclononane). When using alkylbenzenes, the alkylic C(sp3)?H bonds of the substituents remained unmodified, thus the reaction being also selective toward functionalization of sp2 C?H bonds. 相似文献
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. 相似文献
A large variety of synthetic methods have been developed for the synthesis of functionalized aliphatic amines because of their broad spectrum of application. Metallic reagents/catalysts and/or toxic oxidants are involved in most of the cases. Direct C? H functionalization of aliphatic amines via their classical condensation reactions with suitable carbonyl compounds is advantageous because this method avoids hazardous metallic reagents, toxic oxidants and pre‐activation/pre‐functionalization step(s). In this account, the concept of direct C? H functionalization of aliphatic amines based on the classical condensation–isomerization–addition (CIA) strategy followed by recent contributions from our ongoing research in the field along with relevant examples from other groups are described. Successes in stereo‐ and regioselective C? C and C? O bond formation via direct α‐ as well as β‐C(sp3)–H functionalization are discussed.
Regioselective incorporation of a particular functional group into aliphatic sites by direct activation of unreactive C?H bonds is of great synthetic value. Despite advances in radical‐mediated functionalization of C(sp3)?H bonds by a hydrogen‐atom transfer process, the site‐selective vinylation of remote C(sp3)?H bonds still remains underexplored. Reported herein is a new protocol for the regioselective vinylation of unactivated C(sp3)?H bonds. The remote C(sp3)?H activation is promoted by a C‐centered radical instead of the commonly used N and O radicals. The reaction possesses high product diversity and synthetic efficiency, furnishing a plethora of synthetically valuable E alkenes bearing tri‐/di‐/mono‐fluoromethyl and perfluoroalkyl groups. 相似文献
Enantioselective functionalizations of unbiased methylene C(sp3)?H bonds of linear systems by metal insertion are intrinsically challenging and remain a largely unsolved problem. Herein, we report a palladium(II)‐catalyzed enantioselective arylation of unbiased methylene β‐C(sp3)?H bonds enabled by the combination of a strongly coordinating bidentate PIP auxiliary with a monodentate chiral phosphoric acid (CPA). The synergistic effect between the PIP auxiliary and the non‐C2‐symmetric CPA is crucial for effective stereocontrol. A broad range of aliphatic carboxylic acids and aryl bromides can be used, providing β‐arylated aliphatic carboxylic acid derivatives in high yields (up to 96 %) with good enantioselectivities (up to 95:5 e.r.). Notably, this reaction also represents the first palladium(II)‐catalyzed enantioselective C?H activation with less reactive and cost‐effective aryl bromides as the arylating reagents. Mechanistic studies suggest that a single CPA is involved in the stereodetermining C?H palladation step. 相似文献
The selective transformation of C?H bonds is one of the most desirable approaches to creating complexity from simple building blocks. Several directing groups are efficient in controlling the regioselectivity of catalytic C?H bond functionalizations. Among them, carboxylic acids are particularly advantageous, since they are widely available in great structural diversity and at low cost. The carboxylate directing groups can be tracelessly cleaved or may serve as the anchor point for further functionalization through decarboxylative couplings. This Minireview summarizes the substantial progress made in the last few years in the development of reactions in which carboxylate groups direct C?H bond functionalizations with formation of C?C, C?O, C?N, or C?halogen bonds at specific positions. It is divided into sections on C?C, C?O, C?N, and C?halogen bond formation, each of which is subdivided by reactions and product classes. Particular emphasis is placed on methods that enable multiple derivatizations by combining carboxylate‐directed C?H functionalization with decarboxylative couplings. 相似文献