Stereodivergent Palladium-Catalyzed C-F Bond Functionalization of gem-Difluoroalkenes

We herein describe a stereodivergent C-F bond functionalization of gem-difluoroalkenes. Using trisubstituted β,β-difluoroacrylates, both E and Z monofluoroalkene products can be obtained with excellent diastereoselectivities. The design of two different reaction manifolds, i.e., Pd(II)- versus Pd(0)-catalyzed cross-coupling of boronic acids, is the key to stereocontrol.

Recent Advances in Alkenyl sp2 C-H and C-F Bond Functionalizations: Scope, Mechanism, and Applications

Alkenes and their derivatives are featured widely in a variety of natural products, pharmaceuticals, and advanced materials. Significant efforts have been made toward the development of new and practical methods to access this important class of compounds by selectively activating the alkenyl C(sp²)-H bonds in recent years. In this comprehensive review, we describe the state-of-the-art strategies for the direct functionalization of alkenyl sp² C-H and C-F bonds until June 2022. Moreover, metal-free, photoredox, and electrochemical strategies are also covered. For clarity, this review has been divided into two parts; the first part focuses on currently available alkenyl sp² C-H functionalization methods using different alkene derivatives as the starting materials, and the second part describes the alkenyl sp² C-F bond functionalization using easily accessible gem-difluoroalkenes as the starting material. This review includes the scope, limitations, mechanistic studies, stereoselective control (using directing groups as well as metal-migration strategies), and their applications to complex molecule synthesis where appropriate. Overall, this comprehensive review aims to document the considerable advancements, current status, and emerging work by critically summarizing the contributions of researchers working in this fascinating area and is expected to stimulate novel, innovative, and broadly applicable strategies for alkenyl sp² C-H and C-F bond functionalizations in the coming years.

Formation of Fluorovinyl Spiro-[imidazole-indene] and α-Amino-β-naphthalenones via Rh(III)-Catalyzed Cascade C-H Functionalization

An efficacious method for building fluorovinyl spiro-[imidazole-indene] and α-amino-β-naphthalenone skeletons synchronously has been shown to consist of Rh(III)-catalyzed C-H functionalization between 2H-imidazoles and difluoromethylene alkynes. This protocol demonstrates a practical and straightforward route for installing fluorine elements in the envisioned position of heterocyclic compounds.

Iron-catalyzed decarboxylative and oxidative decarbonylative cross-coupling: a new strategy for the synthesis of monofluoroalkenes

Herein, an iron(ii)-catalyzed decarboxylative and oxidative decarbonylative cross-coupling of α-fluoro cinnamic acids with aliphatic aldehydes is presented.

Csp3‒H Monofluoroalkenylation via Stereoselective C‒F Bond Cleavage

A practical nickel- and photoredox-catalyzed Csp3‒H monofluoroalkenylation through chelation-assisted Csp2‒F bond cleavage of gem-difluoroalkenes has been developed, which provides an expedient access to the synthesis of tetrasubstituted fluoroalkenes with complete...

Recent advances in transition-metal catalyzed directed C–H functionalization with fluorinated building blocks

This review focuses on the advances in transition-metal catalyzed reactions with fluorinated building blocks via directed C–H bond activation for the construction of diverse organic molecules with an insight into the probable mechanistic pathway.

Copper-catalyzed direct monofluoroalkenylation of C(sp3)–H bonds via decarboxylation of α-fluoroacrylic acids

Herein, a protocol for the copper-catalyzed direct monofluoroalkenylation of C(sp3)–H bonds is reported.

Synthesis of Dialkyl-Substituted Monofluoroalkenes via Palladium-Catalyzed Cross-Coupling of Alkyl Carbagermatranes

An unprecedented cross-coupling reaction of alkyl carbagermatranes with bromofluoroolefins to deliver dialkyl-substituted monofluoroalkenes was achieved. This cross-coupling reaction was performed under base/additive-free conditions with excellent functional group tolerance, therefore offering an opportunity for challenging dialkyl-substituted monofluoroalkenes. The preparation of bioactive agent analogues including an antitubercular agent mimic and a COX-2 inhibitor analogue and the late-stage fluoroalkenylation of drug-molecule derivatives proved the utility of this strategy.

Synthesis of 2-aminobenzofurans via base-mediated [3 + 2] annulation of N-phenoxy amides with gem-difluoroalkenes

Efficient metal-free [3 + 2] annulation of N-phenoxy amides with gem-difluoroalkenes has been realized for the assembly of 2-aminobenzofuran derivatives with potent cytotoxicity against cancer cell lines and application potential for DELs.

Rhodium(iii)-catalyzed C–H/C–F activation sequence: expedient and divergent synthesis of 2-benzylated indoles and 2,2′-bis(indolyl)methanes

A novel method for the construction of fluorinated 2-benzylated indoles and 2,2’-bis(indolyl)methanes was developed via Rh(iii)-catalyzed C–H/C–F activation of arenes with employing 3,3-difluoro-2-exo-methylidene indolines as cross-coupling partner.

Ruthenium(II)-Catalyzed α-Fluoroalkenylation of Oxime Ethers with gem-Difluorostyrenes via C-H Activation and C-F Cleavage

A novel route for ruthenium(II)-catalyzed α-fluoroalkenylation of oxime ethers with gem-difluorostyrenes via C-H activation and C-F cleavage has been developed for the first time. Notably, the alkenyl units of products exhibit exclusive Z-configuration. This reaction features a broad substrate scope and good functional group tolerance. A plausible reaction mechanism is confirmed by an available cycloruthenated intermediate. Besides, the O-methyl oximyl-directing group can be readily removed to access the α-fluoroalkenylated acetophenones.

Rhodium-Catalyzed Merging of 2-Arylquinazolinone and 2,2-Difluorovinyl Tosylate: Diverse Synthesis of Monofluoroolefin Quinazolinone Derivatives

An efficient method for the synthesis of 2-(o-monofluoroalkenylaryl)quinazolinone derivatives was developed. In this context, the quinazolinone ring served as the inherent directing group, 2,2-difluorovinyl tosylate was used as the monofluoroolefin synthon, and Rh(III)-catalyzed C-H bond difluorovinylation of 2-arylquinazolinons was performed to give the corresponding monofluoroalkene-containing quinazolinons in yields of 65-92%. The method is characterized by broad synthetic utility, mild conditions, and high efficiency.

Recent Advances in Transition Metal-Catalyzed Functionalization of gem-Difluoroalkenes

gem-Difluorinated alkenes are readily accessible building blocks that can undergo functionalization to provide a broad spectrum of fluorinated and non-fluorinated products. Herein, we review recent (since 2017) transition metal-catalyzed transformations of these specialized alkenes and summarize general reactivity patterns of these reactions. Many transition metal-catalyzed reactions undergo net C-F bond functionalization reactions to deliver monofluorinated products. These reactions typically proceed through β-fluoro alkylmetal intermediates that readily eliminate a β-fluoride to deliver monofluoroalkene products. A second series of reactions exploit coinage metal fluorides to add F- to the gem-difluorinated alkene, and further functionalization delivers trifluoromethyl-containing products. In stark contrast, few transition metal-catalyzed reactions proceed in net "fluorine-retentive processes" to deliver difluoromethylene-based products.

Recent advances in three-component difunctionalization of gem-difluoroalkenes

Three-component difunctionalization of gem-difluoroalkenes via the generation and transformation of a α-fluoroalkylated carbanion, a carbon–metal species, a radical, and a carbocation intermediate.

Silver-promoted decarboxylative radical addition/annulation of oxamic acids with gem-difluoroolefins: concise access to CF2-containing 3,4-dihydroquinolin-2-ones

Described is a silver-promoted decarboxylative radical addition/annulation of oxamic acids with gem-difluoroalkenes. This reaction proceeded under mild reaction conditions with broad functional group compatibility, enabling the convenient synthesis of various structurally diverse CF2-containing 3,4-dihydroquinolin-2-ones that might find applications in medical chemistry.

Organic photoredox catalytic decarboxylative cross-coupling of gem-difluoroalkenes with unactivated carboxylic acids

The first redox neutral decarboxylative alkylation of gem-difluoroalkenes via C–F bond activation enabled by organic photoredox catalysis has been developed.

Rh(iii)-Catalyzed α-fluoroalkenylation of N-nitrosoanilines with 2,2-difluorovinyl tosylates via C–H bond activation

Rh(iii)-Catalyzed α-fluoroalkenylation of N-nitrosoanilines with 2,2-difluorovinyl tosylates has been realized, leading to the synthesis of monofluoroalkenes with high Z-selectivity with respect to the olefin.