Mechanochemical Thiolation of α-Imino Ketones: A Catalyst-Free, One-Pot, Three-Component Reaction

Herein, we report an efficient mechanochemical synthesis of α,α-amino thioketones involving a one-pot, three-component milling of 2-oxo aldehydes, amines, and thiols. Unlike previous methods, this protocol does not require any catalyst or oxidizing additive. The reaction proceeds through the thiolation of in situ formed α-imino ketones by liquid-assisted grinding. We have successfully extended this protocol to synthesizing benzothiazoles, thiazoles, and quinoxalines, demonstrating its efficiency and potential in the field. Importantly, we have shown the gram-scale synthesis, synthetic applications, and substrate scope of this protocol, instilling confidence in its practicality.

Aminoarylation of alkynes using diarylanilines

Intermolecular aminoarylation of alkynes is described, via addition of diarylanilines to alkynes and Smiles-Truce rearrangement. The transformation manipulates the C-N bond of anilines directly, with no requirement for organometallic reagents or transition metal catalysis. The enaminoate products are versatile building blocks for different classes of heterocycles.

Efficient synthesis of pentasubstituted pyrroles via intramolecular C-arylation

Immobilized L-aspartic acid beta-methyl ester (Fmoc-Asp(OMe)-OH) was reacted with 4-nitrobenzenesulfonyl chloride, followed by alkylation with various α-haloketones. The resulting intermediates were treated with potassium trimethylsilanolate, which yielded tetrasubstituted pyrroles after a one-step transformation consisting of sequential C-arylation, aldol condensation and spontaneous aromatization. The discovered synthetic strategy enables fast and simple access to pentasubstituted and functionalized pyrroles from a number of readily available starting materials.

A visible light-mediated, decarboxylative, desulfonylative Smiles rearrangement for general arylethylamine syntheses

A decarboxylative, desulfonylative Smiles rearrangement is reported for the synthesis of a wide range of biologically relevant arylethylamines, including fluorinated phenylethylamines, heterocyclic amphetamines and an unnatural amino acid.

Arylation and alkenylation of activated alkyl halides using sulfonamides

A variety of quaternary aryl amino acid derivatives can be synthesised using tandem S_N2/Smiles rearrangement chemistry involving aryl sulfonamides and α-chloro carbonyl compounds.

CBr4-mediated cross-coupling reactions of α-amino carbonyl compounds with alcohols and thiols to build C–O and C–S bonds, respectively

The direct C(sp³)–H bond functionalization of α-amino carbonyl compounds with CBr₄ to construct C–O and C–S bonds.

The Truce–Smiles rearrangement and related reactions: a review

The Truce–Smiles rearrangement is an X → C aryl migration reaction that is achieved by an intramolecular nucleophilic aromatic substitution pathway. The reaction exhibits a wide substrate scope with respect to a migrating aryl ring and leaving group, appearing in many different tandem reaction sequences, to achieve a wide variety of product outcomes. We present an extensive survey of reported examples of the Truce–Smiles rearrangement from the chemistry literature (1950s until present) organized by various substrate design variables or aspects of the reaction method. Present deficiencies in our understanding of the reaction are identified with recommendations for future research directions and useful developments in the application of the reaction are celebrated.

Iron-catalyzed direct α-arylation of α-amino carbonyl compounds with indoles

A mild and general α-arylation of α-amino carbonyls with indoles catalyzed by Fe(ClO4)3 has been developed. C-H activation is smoothly fulfilled by using TBHP as the oxidant with good yields. Two hydrogen dissociations make this transformation more environmentally benign because of high atom efficiency.

Mining the Chemical Space: Application of 2/4-Nitrobenzenesulfonamides in Solid-Phase Synthesis

Polymer-supported benzenesulfonamides prepared from various immobilized primary amines and 2/4-nitrobenzenesulfonyl chloride have been used as key intermediates in different chemical transformations, including unusual rearrangements to yield a number of diverse privileged scaffolds. This review summarizes individual strategies in their application to date.

Benzhydrylamines via base-mediated intramolecular sp(3) C-arylation of N-benzyl-2-nitrobenzenesulfonamides--advanced intermediates for the synthesis of nitrogenous heterocycles

N-Benzyl-2-nitrobenzenesulfonamides underwent base-mediated intramolecular arylation at the benzyl sp(3) carbon to yield benzhydrylamines. The presence of electron withdrawing groups on the aromatic ring of the benzyl group was required to facilitate the C-arylation. Unsymmetrically substituted benzhydrylamines are advanced intermediates toward nitrogenous heterocycles, as exemplified in the syntheses of indazole oxides and quinazolines.

Base-mediated intramolecular C- and N-arylation of N,N-disubstituted 2-nitrobenzenesulfonamides: advanced intermediates for the synthesis of diverse nitrogenous heterocycles

Structural and electronic features that facilitate and direct the intramolecular C- and N-arylation of 2-alkyl-2-{[N-(benzyl)-2-nitrophenyl]sulfonamido}acetic acid esters and amides were examined. The substitution pattern and amino acid carboxy-terminal functionality determined the arylation position. C/N-arylated products represent advanced intermediates for combinatorial synthesis of diverse nitrogenous heterocycles, including indazoles, quinazolinones, quinoxalinones, and 3-amino-2-oxindoles.

Fluoroponytailed crown ethers and quaternary ammonium salts as solid-liquid phase transfer catalysts in organic synthesis

Fluorous derivatives of dibenzo-18-crown-6 ether were prepared, and then successfully applied in representative solid-liquid phase transfer catalysis reactions, which were performed in standard organic solvents, such as chlorobenzene and toluene, as well as in fluorous solvents, such as perfluoro-1,3-dimethylcyclohexane. It was clearly shown that properly designed fluoroponytailed crown ethers could promote the disintegration of the crystal lattice of alkali salts, and transfer anions from the solid surface into an apolar, non-coordinating perfluorocarbon phase, for phase transfer catalysis reactions in organic synthesis. Furthermore, 3,5-bis(perfluorooctyl)benzyl bromide and triethylamine were reacted under mild conditions to provide an analogue of the versatile phase transfer catalyst, benzyltriethylammonium chloride, containing two fluoroponytails. This fluoroponytailed quaternary ammonium salt was also successfully employed as a catalyst in a variety of organic reactions conducted under solid-liquid phase transfer catalysis conditions, without a perfluorocarbon phase. Thus, being both hydrophobic and lipophobic, fluorous crown ethers and ammonium salts, could be rapidly recovered in quantitative yields, and reused without loss of activity, over several reaction cycles.