Synthesis and Characterization of β-Trifluoromethyl-Substituted Pyrrolidines

α-Fluorination of tropane compounds and its impact on physicochemical and ADME properties

Using an electrochemical C(sp3)-H fluorination reaction, a series of α-fluorinated tropane compounds were synthesized and their druglikeness parameters were assessed to compare with the parent compounds. Improvements were observed in membrane permeability, P-gp liability, and inhibitory effects on hERG and Nav1.5 channels, accompanied with a trend of decreased aqueous solubility and microsomal stability. It was also revealed that α-fluorination reduced the basicity of tropane nitrogen atom for about 1000-fold.

[3+2] Cycloaddition of Alkynyl Boronates and in situ Generated Azomethine Ylide

Scalable [3+2] cycloaddition of alkynyl boronates and in situ generated unstabilized azomethine ylide is reported for the first time. The selective formation of either 1 : 1 or 1 : 2 cycloaddition products was achieved by carefully optimizing the reaction conditions, mainly by controlling the reactant stoichiometry, catalyst loading, and internal temperature. The developed protocol tolerated many valuable functional groups, including TMS, protected alcohol (as ether or THP derivatives), or aldehyde (as acetal). Further common C-C and C-heteroatom bond-forming reactions, as well as scaled-up procedures demonstrate the utility of the prepared compounds as building blocks for organic synthesis and drug discovery.

Bicyclic Pyrrolidines for Medicinal Chemistry via [3 + 2]-Cycloaddition

A general approach to bicyclic fused pyrrolidines via [3 + 2]-cycloaddition between nonstabilized azomethyne ylide and endocyclic electron-deficient alkenes was elaborated. "Push-pull" alkenes and CF₃-alkenes did not react with the azomethyne ylide under the previously reported conditions, and we developed a superior protocol (LiF, 140 °C, no solvent). Among obtained products were medchem-relevant bicyclic sulfones, monofluoro-, difluoro-, and trifluoromethyl-substituted pyrrolidines. This approach not only allowed preparation of novel molecules but also significantly simplified synthesis of the existing ones (e.g., sofinicline).

Applications of 2-Chloro-3,3,3-trifluoroprop-1-ene (HCFO-1233xf): A Rapid Entry to Various β-Substituted-trifluoromethyl-ethenes

An efficient base-promoted reaction of O-, N-, and S-nucleophiles with 2-chloro-3,3,3-trifluoprop-1-ene (HCFO-1233xf) is described providing access to various β-substituted-trifluoromethyl-ethenes under mild reaction conditions. Mechanistic investigations shed some light on the regio-, chemo-, and stereoselectivities observed. The olefins prepared represent attractive intermediates in chemical discovery: some applications include their conversion to pyrrolidines via a [3 + 2] dipolar cycloaddition reaction. These weakly basic amines represent novel synthons that could be readily elaborated through a range of reactions.

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.

Asymmetric synthesis of polycyclic 3-fluoroalkylproline derivatives by intramolecular azomethine ylide cycloaddition

The asymmetric intramolecular dipolar cycloaddition of azomethine ylides was developed for fluorinated dipolarophiles, being the RF group crucial for selectivity.

Comparative effects of trifluoromethyl- and methyl-group substitutions in proline

What is the outcome of trifluoromethyl-/methyl-substitution in each position of the proline ring? Look inside to find out.

Synthesis of Spirocyclic Pyrrolidines: Advanced Building Blocks for Drug Discovery

In the context of drug discovery, novel spirocyclic pyrrolidines have been synthesized in two steps from common three- to seven-membered-ring (hetero)alicyclic ketones. The key transformation is a reaction between an electron-deficient exocyclic alkene and an in situ generated N-benzyl azomethine ylide. The developed method has been used to synthesize the central diamine core of the known antibacterial agents Sitafloxacin and Olamufloxacin.

Photoorganocatalysed and visible light photoredox catalysed trifluoromethylation of olefins and (hetero)aromatics in batch and continuous flow

Trifluoromethylation of olefins and (hetero)aromatics with sodium triflinate as CF₃source and readily accessible benzophenone derivatives as photosensitisers has been developed in batch and flow.