Synthesis of Trifluoromethyl-Substituted 3-Azabicyclo[n.1.0]alkanes: Advanced Building Blocks for Drug Discovery

Impact of trifluoromethyl and sulfonyl groups on the biological activity of novel aryl-urea derivatives: synthesis, in-vitro, in-silico and SAR studies

We designed and prepared a novel series of urea derivatives with/without sulfonyl group in their structures to investigate the impact of the sulfonyl group on the biological activity of the evaluated compounds. Antibacterial investigations indicated that derivatives 7, 8, 9, and 11 had the most antibacterial property of all the compounds examined, their minimum inhibitory concentrations (MICs) determined against B. mycoides, E. coli, and C. albicans, with compound 8 being the most active at a MIC value of 4.88 µg/mL. Anti-cancer activity has been tested against eight human cancer cell lines; A549, HCT116, PC3, A431, HePG2, HOS, PACA2 and BJ1. Compounds 7, 8 and 9 emerged IC50 values better than Doxorubicin as a reference drug. Compounds 7 and 8 showed IC50 = 44.4 and 22.4 μM respectively against PACA2 compared to Doxorubicin (IC50 = 52.1 μM). Compound 9 showed IC50 = 17.8, 12.4, and 17.6 μM against HCT116, HePG2, and HOS, respectively. qRT-PCR revealed the down-regulation of PALB2 in compounds 7 and 15 treated PACA2 cells. Also, the down-regulation of BRCA1 and BRCA2 was shown in compound 7 treated PC3 cells. As regard A549 cells, compound 8 decreased the expression level of EGFR and KRAS genes. While compounds 7 and 9 down-regulated TP53 and FASN in HCT116 cells. Molecular docking was done against Escherichia coli enoyl reductase and human Son of sevenless homolog 1 (SOS1) and the results showed the promising inhibition of the studied proteins.

Synthesis of di/trifluoromethyl cyclopropane-dicarbonitriles via [2+1] annulation of fluoro-based diazoethanes with (alkylidene)malononitriles

Herein, we describe a [2+1] annulation reaction of di/trifluorodiazoethane with (alkylidene)malononitriles. This protocol offers a streamlined synthesis of a wide range of stereospecific and densely functionalized difluoromethyl and trifluoromethyl cyclopropane-1,1-dicarbonitriles. Further functional group interconversions or skeletal elaborations afford structurally distinct cyclopropyl variants.

Ag-Catalyzed Annulation of o-Alkynylaryl Aldehydes, Amines, and Diazo Compounds: Construction of Trifluoromethyl- and Cyano-Functionalized Benzo[d]azepines

A Ag-catalyzed three-component annulation protocol, which uses o-alkynylaryl aldehydes, amines, and trifluorodiazoethane or diazoacetonitrile, to forge a new class of trifluoromethyl- and cyano-functionalized benzo[d]azepine is presented in this Letter. The key transformations involved in this reaction are the transient formation of the isoquinolinium intermediate and the subsequent ring-expansive addition of in situ-formed silver trifluorodiazoethylide to this intermediate. The practicality of this protocol is illustrated by realizing access to a wide range of densely functionalized benzo[d]azepines.

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

A synthetic route to the bench-stable fluorinated masked carbene reagent diethyl 2-diazo-1,1,3,3,3-pentafluoropropylphosphonate, bearing a trifluoromethyl and a difluoromethyl group is reported for the first time. Its application in CuI-catalyzed cyclopropanation reactions with aromatic and aliphatic terminal alkenes under mild reaction conditions is demonstrated. In total, sixteen new cyclopropanes were synthesized in good to very good yields.

New strategies for the synthesis of 1- and 2-azetines and their applications as value-added building blocks

Four-membered nitrogen-containing heterocycles are highly desirable functional groups with synthetic and biological applications. Unsaturated four-membered N-heterocycles, 1- and 2-azetines, are historically underexplored, but have recently been gaining interest due to the development of new synthetic methods to access these compounds, and to their potential as reactive intermediates. This review covers both the synthesis and applications of azetines, with a focus on synthetic methods to access azetines developed since 2018, and a comprehensive review of the reactivity and applications of azetines as starting materials or intermediates to access both other heterocycles and complex products.

Fluoral Hydrate: A Perspective Substrate for the Castagnoli-Cushman Reaction

The reactivity of azomethines based on trifluoroacetaldehyde hydrate in the Castagnoli-Cushman reaction (CCR) was researched. The impact of the nature of anhydrides explored on the reaction route was determined. The preparative procedures for the synthesis of N-substituted (3R*,4R*)-1-oxo-3-(trifluoromethyl)-1,2,3,4-tetrahydroisoquinoline-4-carboxylic and (1R*,2R*)-4-oxo-2-(trifluoromethyl)-2,3,4,5-tetrahydro-1H-benzo[d]azepine-1-carboxylic acids in gram scales were elaborated. It was shown that the trifluoromethyl group remarkably decreased the reactivity of azomethines in CCR. The mechanism for the formation of different products depending on the anhydride's nature was proposed.

Deoxofluorination of (Hetero)aromatic Acids

Diverse trifluoromethyl-substituted compounds were synthesized by deoxofluorination of cinnamic and (hetero)aromatic carboxylic acids with sulfur tetrafluoride. The obtained products were used as starting materials in the preparation of novel fluorinated amino acids, anilines, and aliphatic amines - valuable building blocks for medicinal chemistry and agrochemistry.

Deoxofluorination of Aliphatic Carboxylic Acids: A Route to Trifluoromethyl-Substituted Derivatives

A practical method for the synthesis of functionalized aliphatic trifluoromethyl-substituted derivatives from aliphatic acids is developed. The transformation proceeds with sulfur tetrafluoride in the presence of water as a key additive. Compared to previous methods, the reaction gives products with full retention of stereo- and absolute configuration of chiral centers.

Mild and Diazo-Free Synthesis of Trifluoromethyl-Cyclopropanes Using Sulfonium Ylides

The synthesis of several 1,1-disubstituted trifluoromethyl-cyclopropanes (TFCPs), known as tert-butyl bioisosteres, has been achieved from the reaction between trifluoromethylalkenes and unstabilized sulfonium ylides in yields of ≤97%. This method offers practical access to this cyclopropyl moiety of pharmacological interest, employing a commercially available reagent at low temperatures. The synthesis of cyclopropanes bearing other electron-withdrawing groups as well as trisubstituted TFCPs was also accomplished.

Chemistry of Bridged Lactams: Recent Developments

Bridged lactams represent the most effective and wide-ranging method of constraining the amide bond in a non-planar conformation. A previous comprehensive review on this topic was published in 2013 (Chem. Rev.2013, 113, 5701–5765). In the present review, which is published as a part of the Special Issue on Amide Bond Activation, we present an overview of the recent developments in the field of bridged lactams that have taken place in the last five years and present a critical assessment of the current status of bridged lactams in synthetic and physical organic chemistry. This review covers the period from 2014 until the end of 2018 and is intended as an update to Chem. Rev.2013, 113, 5701–5765. In addition to bridged lactams, the review covers recent advances in the chemistry of bridged sultams, bridged enamines and related non-planar structures.

Highly enantioselective synthesis of trifluoromethyl cyclopropanes by using Ru(ii)–Pheox catalysts

An asymmetric synthesis of various trifluoromethyl cyclopropanes from olefins, such as vinyl ferrocene, vinyl ethers, vinyl amines, vinyl carbamates and dienes, was achieved by using Ru(ii)–Pheox catalysts.

Heptafluoroisopropyl diazomethane (i-C3F7CHN2): in situ generation and synthesis of pyrazoles

A novel chemical reagent, heptafluoroisopropyl diazomethane (i-C₃F₇CHN₂), has been generated in situ in aqueous media. It reacts with electron-deficient alkynes towards polyfluorinated pyrazoles that are important in agrochemistry.

Fluoroalkyl-Substituted Diazomethanes and Their Application in a General Synthesis of Pyrazoles and Pyrazolines

A novel continuous-flow approach for the synthesis of fluoroalkyl-substituted diazomethanes has been developed. Utilizing a cheap, self-made microreactor fluoroalkyl-substituted amines were transformed into the corresponding diazomethanes using tert-butyl nitrite and acetic acid as catalyst. These diazomethanes were employed in [2+3] cycloaddition reactions with olefins and alkynes, yielding valuable pyrazolines and pyrazoles in good to excellent yields.

Generation and Synthetic Application of Trifluoromethyl Diazomethane Utilizing Continuous Flow Technologies

A continuous process for the synthesis and inline separation of anhydrous trifluoromethyl diazomethane in a single continuous flow process is presented. The diazo building block is generated from the corresponding amine and NaNO2 under acidic, aqueous conditions and subsequently diffuses through a gas-permeable membrane into an organic stream. To avoid storage and transportation of the hazardous compound, a representative downstream process in a packed-bed reactor yielding highly functionalized building blocks was developed.

Fluorinated diazoalkanes – a versatile class of reagents for the synthesis of fluorinated compounds

Fluorinated diazo compounds were long neglected in organic synthesis. This review discusses the flourishing chemistry of these reagents, ranging from C–H activation to cycloadditions for the synthesis of fluorinated compounds.

Rhodium catalyzed synthesis of difluoromethyl cyclopropanes

Difluoromethyl-substituted cyclopropanes still remain one of the most challenging class of substrates.