Organic chemistry frontiers : an international journal of organic chemistry最新文献

A facile approach toward 3-(o-aminophenyl)pyrroles was developed by remodeling of N-sulfonyl-3-acyl indoles with N-phenylglycines under photoredox catalysis. This strategy enables the conversion of a fused bicyclic system into a biaryl scaffold, mechanically involving a Giese-type radical addition to C2C3, C2–N cleavage of the resulting indoline skeleton, and generation of a new pyrrole motif. This novel methodology provides an innovative strategy for the synthesis of potentially valuable 3-(o-aminophenyl)pyrroles and related alkaloids.

Herein, we report the synthesis of binaphthyl-derived hoop-shaped aromatic hydrocarbon enantiomers (RCR and SCR) as the segments of (9,9) armchair CNTs. After the structures were identified by HR-MS (MALDI-TOF) and NMR spectroscopy, further circular dichroism (CD) analysis confirmed their chirality. Unlike most of the previously reported chiral-type CNT segments in which chirality arises from the absence of a plane of symmetry or an inversion center in the molecule, the chirality for RCR and SCR is assigned to the introduction of foreign chiral sources, namely, oxyethyl-modified binaphthyl units. Finally, their photophysical properties were also investigated by absorption and fluorescence spectroscopies.

Disclosed herein is a novel one-pot synthesis of C3-sulfonate esters and C4-chlorides of quinolines from quinoline N-oxides with sulfonyl chloride. Sulfonyl chlorides were used in two roles, namely sulfonylation and chlorination. Both arenesulfonyl chlorides and aliphatic sulfonyl chlorides were found to be suitable precursors for sulfonation and chlorination reagents. Therefore, a wide variety of C3-sulfonate esters and C4-chlorides of quinolines were afforded under metal-free conditions. This procedure features practicality, high efficiency, environmental friendliness and atomic economy.

A simple, efficient, and mild reaction of 2-chloroprop-2-ene-1-sulfonyl fluoride (CESF) with amines was developed, affording a variety of highly functionalized enaminyl sulfonyl fluorides in good to excellent yields (56–96%). This transformation features a broad substrate scope, high atom economy, operational simplicity and up to 100% stereoselectivity, which can provide great application value in medicinal chemistry, chemical biology, and drug discovery.

A novel dearomative 1,4-rearrangement reaction of 2-carbonateindoles with aryl diazoacetates has been developed in the presence of a copper catalyst, which might proceed through a tandem formation of a zwitterionic intermediate, intramolecular cyclization and ring-opening reaction to give the final rearrangement products containing an all-carbon quaternary center with two newly formed C–C bonds. In this sequence, the disruption of the aromaticity of indole has been realized, associated with 1,4-carboxylate rearrangements.

Herein, we report a visible light-induced photocatalytic protocol for the thiolation and pyridylation of styenes using a thiolate-based EDA complex as a bifunctional reagent. The reaction occurrs under mild conditions free of a photocatalyst, metal or external redox agent, possessing a broad substrate scope. The protocol can be practiced on the gram-scale, and late-stage functionalization of natural product- and drug-derived complex molecules is also possible.

A new, metal-free electron donor–acceptor (EDA) complex photocatalysis strategy for alkylative [3 + 2] annulation of N-alkyl isoquinolin-2-ium salts with common alkynes in ethyl actate/H₂O to assemble highly functionalized pyrrolo[2,1-a]isoquinolines is presented. Upon photoinducing reactivity using the catalytic isoquinoline-based EDA complex, this method enables incorporation of alkynes as two-carbon units to achieve alkylative [3 + 2] annulation of N-alkyl isoquinolin-2-ium salts, and is notable for its excellent site selectivity, tolerance of a wide range of functional groups, the use of aqueous media and avoidance of the need for expensive external photocatalysts and basic or acidic promotors. Mechanistic study indicates that the EDA complex is generated from association of a catalytic isoquinoline with N-alkyl isoquinolin-2-ium salts to photoinduce reactivity.

A hemin/t-BuOOH-catalyzed oxidative phenol–enamine formal [3 + 2] cycloaddition has been developed, enabling the environmentally benign synthesis of valuable cyclopenta[b]benzofuran scaffolds under sustainable reaction conditions with excellent atom- and step-economy. Mechanistic studies point to the involvement of a two-electron oxidation pathway. Based on the preliminary biological investigations, compound 3ay displayed moderate anti-cancer activities (IC₅₀ = 27.73 μM) against MCF7 cells (breast cancer cells).

A Cu-catalysed method that selectively incorporates a trifluoromethyl group and an alkene moiety onto the α carbon of glycine derivatives has been developed using commercialized Togni II reagent. In this three-component reaction, both the N-protecting group of glycinates and the Cu ligand played critical roles in controlling the catalytic activity and chemo-selectivity. Under the optimized conditions, a variety of unactivated alkenes were successively trifluoromethylated and coupled with N-PMP glycine derivatives, providing facile access to structurally diverse CF₃-containing amino acids, as well as functionalized peptides. In addition, this protocol also demonstrated potential application in the ligation between an alkene-tagged functional molecule and a peptide with a glycine N-terminus.

Iron-mediated divergent reductive coupling reactions of heteroarenes with alkenes have been developed. By switching the substituent site at the C2 and C4 positions of quinolines, either C2 Minisci alkylation or C4 reductive alkylation could be achieved. These approaches feature mild conditions and sensitive functional group tolerance, which enables the functionalization of natural products and medicines. Mechanism investigation revealed that Fe(dibm)₃ would be a dual promoter for both alkyl radical transfer and generation of the more reactive hydrogen donor Ph(RO)SiH_2.