Trifluoromethylation Of Alkenes Research Articles

NMP and O2 as Radical Initiator: Trifluoromethylation of Alkenes to Tertiary β-Trifluoromethyl Alcohols at Room Temperature.

A novel strategy was developed to trigger ·CF3 by using in situ generated peroxide in NMP under O2 or air as the radical initiator. Radical trifluoromethylation of alkenes was achieved toward tertiary β-trifluoromethyl alcohols. Various tertiary β-trifluoromethyl alcohols can be synthesized in good yields without extra oxidants or transition metal catalysts. Preliminary mechanistic investigation revealed that O2 diffusion can influence the reaction rate.

ChemInform Abstract: Copper‐Catalyzed Trifluoromethylation of Alkenes: Synthesis of Trifluoromethylated Benzoxazines.

AbstractA base and ligand free Cu‐catalyzed method for the construction of trifluoromethylated benzoxazines (III), (V), and (VII) is developed.

ChemInform Abstract: Trifluoromethylation‐Initiated Remote Cross‐Coupling of Carbonyl Compounds to Form Carbon—Heteroatom/Carbon Bonds.

By involving the reversal of conventional reactivity expectations without external oxidants, we describe a novel and convenient protocol of remote cross-coupling of carbonyl compounds with a series of common and simple nucleophiles. This cross-coupling is triggered by radical trifluoromethylation of alkenes, thereby achieving highly selective remote difunctionalization of alkenes and α-position of the carbonyl group for facile access to trifluoromethyl α-halo- and α-cyanocarbonyl compounds. The reaction exhibits a broad substrate scope with excellent functionality tolerance and many different types of nucleophiles; further synthetic applicability of the obtained compounds proved to be suitable, thus showing great potential for synthetic utility.

Trifluoromethylation of aromatic alkenes by visible-light-driven photoredox catalysis: Direct conversion of alkenes to 3-trifluoromethyl-1-propenyl and 1,3-bis(trifluoromethyl)-1-propenyl derivatives

Photoredox-catalyzed trifluoromethylation of alkenes using Umemoto's reagent as a CF3 source under visible light irradiation has been developed. A Ru photocatalyst, [Ru(bpy)3](PF6)2 (bpy = 2,2′-bipyridine), is useful for the present trifluoromethylation and preferable formation of 3-trifluoromethyl-1-propenyl derivatives is observed. Use of an excess amount of Umemoto's reagent readily induces double trifluoromethylation of electron-rich alkenes, resulting in 1,3-bis(trifluoromethyl)-1-propenyl skeleton.

ChemInform Abstract: Phosphine‐Catalyzed Remote β‐C—H Functionalization of Amines Triggered by Trifluoromethylation of Alkenes: One‐Pot Synthesis of Bistrifluoromethylated Enamides and Oxazoles.

AbstractThis phosphine‐catalyzed tandem radical process enables the selective and concomitant functionalization of an unactivated alkene and the remote β‐C—H bond of amine derivatives, providing a facile access to bistrifluoromethylated enamides with good regio‐, chemo‐, and stereoselectivity under metal‐free conditions.

ChemInform Abstract: Metal‐Free Direct 1,6‐ and 1,2‐Difunctionalization Triggered by Radical Trifluoromethylation of Alkenes.

AbstractThe direct remote trifluoromethylation combined with an additional functionalization of 1‐alkenes furnishes valuable trifluoromethyl α‐hydroxycarbonyl compounds.

Product Control in Alkene Trifluoromethylation: Hydrotrifluoromethylation, Vinylic Trifluoromethylation, and Iodotrifluoromethylation using Togni Reagent.

Hydrotrifluoromethylation, vinylic trifluoromethylation, and iodotrifluoromethylation of simple alkenes have been achieved by using Togni reagent in the absence of any transition metal catalyst. These reactions were readily controllable by selection of appropriate salts and solvents. The addition of K2CO3 afforded the hydrotrifluoromethylation product, with DMF acting not only as a solvent, but also as the hydrogen source. In contrast, the use of tetra-n-butylammonium iodide (TBAI) in 1,4-dioxane resulted in vinylic trifluoromethylation, while the use of KI afforded the iodotrifluoromethylation product. The vinylic trifluoromethylation product was obtained by treatment of the iodotrifluoromethylation product with ammonium 2-iodobenzoate, indicating that it was formed through an elimination reaction of the in-situ-generated iodotrifluoromethylation product, and the solubility of the resulting 2-iodobenzoate salt plays a key role in the product switching. A radical-clock experiment showed that these reactions proceed via radical intermediates.

Alkene Trifluoromethylation-Initiated Remote α-Azidation of Carbonyl Compounds toward Trifluoromethyl γ-Lactam and Spirobenzofuranone-Lactam

The first unprecedented one-pot domino strategy toward diverse CF3-containing γ-lactam and spirobenzofuranone-lactam scaffolds of antibacterial armeniaspirole from readily available acyclic precursors was developed. The key point of this transformation was the concurrent incorporation of CF3 and azide into the alkene and remote carbonyl α-C–H position via carbonyl-stabilized radical intermediate triggered by alkene trifluoromethylation via a 1,5-H shift in a highly controlled site-selective manner. Furthermore, gram-scale synthesis and synthetic applicability of these compounds proved suitable.

Trifluoromethylation-initiated remote cross-coupling of carbonyl compounds to form carbon-heteroatom/carbon bonds.

By involving the reversal of conventional reactivity expectations without external oxidants, we describe a novel and convenient protocol of remote cross-coupling of carbonyl compounds with a series of common and simple nucleophiles. This cross-coupling is triggered by radical trifluoromethylation of alkenes, thereby achieving highly selective remote difunctionalization of alkenes and α-position of the carbonyl group for facile access to trifluoromethyl α-halo- and α-cyanocarbonyl compounds. The reaction exhibits a broad substrate scope with excellent functionality tolerance and many different types of nucleophiles; further synthetic applicability of the obtained compounds proved to be suitable, thus showing great potential for synthetic utility.

Metal-free direct 1,6- and 1,2-difunctionalization triggered by radical trifluoromethylation of alkenes.

A metal-free direct remote C-H functionalization triggered by radical trifluoromethylation of alkenes was explored, realizing highly selective 1,6-difunctionalization of alkenes toward valuable trifluoromethyl α-hydroxycarbonyl compounds. Furthermore, a metal-free direct intermolecular regioselective 1,2-oxytrifluoromethylation of alkenes is also disclosed. With Togni's reagent as both the CF3 source and oxidant, the reaction exhibits a broad substrate scope with excellent functionality tolerance under mild metal-free conditions, thus showing great potential for synthetic utility.

Back Cover: Phosphine-Catalyzed Remote β-CH Functionalization of Amines Triggered by Trifluoromethylation of Alkenes: One-Pot Synthesis of Bistrifluoromethylated Enamides and Oxazoles (Angew. Chem. Int. Ed. 13/2015)

A CF3 radical could be generated from Togni's reagent in a single-electron-transfer process catalyzed by a simple phosphine. In their Communication on page 4041 ff., B. Tan, X.-Y. Liu, and co-workers utilize this chemistry to realize the first phosphine-catalyzed radical tandem route that enables the concomitant functionalization of an alkene and the remote β-CH bond of amine derivatives to give bistrifluoromethylated enamides and trisubstituted 5-(trifluoromethyl)oxazoles, respectively.

Phosphine‐Catalyzed Remote β‐CH Functionalization of Amines Triggered by Trifluoromethylation of Alkenes: One‐Pot Synthesis of Bistrifluoromethylated Enamides and Oxazoles

AbstractAn unprecedented phosphine‐catalyzed remote β‐CH functionalization of amine derivatives triggered by trifluoromethylation of an alkene with Togni’s reagent was disclosed. This reaction proceeded through the highly selective and concomitant activation of an unactivated alkene and the β‐CH bond of an amine derivative, providing bistrifluoromethylated enamides in excellent yields with good regio‐, chemo‐, and stereoselectivity. Furthermore, the newly developed one‐pot protocol provides a facile and step‐economical access to valuable trisubstituted 5‐(trifluoromethyl)oxazoles. Mechanistic studies showed that this reaction may initiate with a novel phosphine‐catalyzed radical trifluoromethylation of unactivated alkene via a phosphorus radical cation.

Phosphine‐Catalyzed Remote β‐CH Functionalization of Amines Triggered by Trifluoromethylation of Alkenes: One‐Pot Synthesis of Bistrifluoromethylated Enamides and Oxazoles

An unprecedented phosphine-catalyzed remote β-CH functionalization of amine derivatives triggered by trifluoromethylation of an alkene with Togni's reagent was disclosed. This reaction proceeded through the highly selective and concomitant activation of an unactivated alkene and the β-C sp 3H bond of an amine derivative, providing bistrifluoromethylated enamides in excellent yields with good regio-, chemo-, and stereoselectivity. Furthermore, the newly developed one-pot protocol provides a facile and step-economical access to valuable trisubstituted 5-(trifluoromethyl)oxazoles. Mechanistic studies showed that this reaction may initiate with a novel phosphine-catalyzed radical trifluoromethylation of unactivated alkene via a phosphorus radical cation.

Copper(I)-photocatalyzed trifluoromethylation of alkenes.

Using the photoreducible Cu(II) precatalyst 2, trifluoromethylation reactions of alkenes are conducted effectively at low copper loading (0.1-0.5 mol%) on exposing the reaction mixture to sunlight/ambient light.

Mechanisms and applications of cyclometalated Pt(ii) complexes in photoredox catalytic trifluoromethylation.

The incorporation of a trifluoromethyl group into an existing scaffold can provide an effective strategy for designing new drugs and agrochemicals. Among the numerous approaches to trifluoromethylation, radical trifluoromethylation mediated by visible light-driven photoredox catalysis has gathered significant interest as it offers unique opportunities for circumventing the drawbacks encountered in conventional methods. A limited understanding of the mechanism and molecular parameters that control the catalytic actions has hampered the full utilization of photoredox catalysis reactions. To address this challenge, we evaluated and investigated the photoredox catalytic trifluoromethylation reaction using a series of cyclometalated Pt(ii) complexes with systematically varied ligand structures. The Pt(ii) complexes were capable of catalyzing the trifluoromethylation of non-prefunctionalized alkenes and heteroarenes in the presence of CF3I under visible light irradiation. The high excited-state redox potentials of the complexes permitted oxidative quenching during the cycle, whereas reductive quenching was forbidden. Spectroscopic measurements, including time-resolved photoluminescence and laser flash photolysis, were performed to identify the catalytic intermediates and directly monitor their conversions. The mechanistic studies provide compelling evidence that the catalytic cycle selects the oxidative quenching pathway. We also found that electron transfer during each step of the cycle strictly adhered to the Marcus normal region behaviors. The results are fully supported by additional experiments, including photoinduced ESR spectroscopy, spectroelectrochemical measurements, and quantum chemical calculations based on time-dependent density functional theory. Finally, quantum yields exceeding 100% strongly suggest that radical propagation significantly contributes to the catalytic trifluoromethylation reaction. These findings establish molecular strategies for designing trifluoromethyl sources and catalysts in an effort to enhance catalysis performance.

Copper-catalyzed trifluoromethylation of alkenes: synthesis of trifluoromethylated benzoxazines.

A simple base and ligand free copper catalyzed method for the construction of trifluoromethylated benzoxazines has been developed by using Umemoto's reagent. It involves the oxidative difunctionalization of alkenes through tandem C-O and C-CF3 bond formations. Furthermore, synthesized benzoxazines were selectively converted into trifluoromethylated allylic and (E)-vinylic benzamides by the treatment of KO(t)Bu and CH3Li, respectively.

Transition Metal‐Free Trifluoromethylation of N‐Allylamides with Sodium Trifluoromethanesulfinate: Synthesis of Trifluoromethyl‐Containing Oxazolines

AbstractA transition metal‐free method for the trifluoromethylation of N‐allylamides has been developed, and the corresponding trifluoromethyl‐containing oxazolines were prepared in moderate to good yields. The protocol uses readily available substituted N‐allylamides as the starting materials, inexpensive and easily stored sodium trifluoromethanesulfinate as the trifluoromethyl source, iodobenzene diacetate as the oxidant, and the procedure involves sequential intermolecular trifluoromethylation of alkenes with sodium trifluoromethanesulfinate and intramolecular cyclization. This is the first example to prepare CF3‐containing oxazolines. Therefore, the present method should afford an efficient and practical strategy for synthesis of other CF3‐containing cyclic compounds.magnified image

ChemInform Abstract: Trifluoromethylation of Alkenes with Concomitant Introduction of Additional Functional Groups

AbstractReview: [68 refs.

Cascade multicomponent synthesis of indoles, pyrazoles, and pyridazinones by functionalization of alkenes.

The development of multicomponent reactions for indole synthesis is demanding and has hardly been explored. The present study describes the development of a novel multicomponent, cascade approach for indole synthesis. Various substituted indole derivatives were obtained from simple reagents, such as unfunctionalized alkenes, diazonium salts, and sodium triflinate, by using an established straightforward and regioselective method. The method is based on the radical trifluoromethylation of alkenes as an entry into Fischer indole synthesis. Besides indole synthesis, the application of the multicomponent cascade reaction to the synthesis of pyrazoles and pyridazinones is described.

ChemInform Abstract: Recent Advances in Trifluoromethylation of Organic Compounds Using Umemoto′s Reagents

AbstractReview: [64 refs.