Palladium-Catalyzed Strain-Enabled [2π + 2σ] Cycloadditions of Vinyl Bicyclo[1.1.0]butanes with Methyleneindolinones.

A palladium-catalyzed [2π + 2σ] cycloaddition of vinyl bicyclo[1.1.0]butanes with methyleneindolinones has been developed.

Structure-Dependent, Switchable Alder-Ene/[2π + 2σ] Cycloadditions of Vinyl Bicyclo[1.1.0]butanes with α-Ketoesters Enabled by Palladium Catalysis.

A structure-dependent, palladium-catalyzed switchable alder-ene/[2π + 2σ] cycloaddition of VBCBs with α-ketoesters has been reported. A variety of cyclobutenes and 2-oxabicyclo[2.1.

Au(I)/Sc(III)-co-catalyzed tandem spiroannulation/cycloisomerization of 3-(2-ethynylaryl)--tosylaziridines with indoles to access 5-benzo[]carbazoles.

An unusual spiroannulation/cycloisomerization cascade of 3-(2-ethynylaryl)--tosylaziridines with indoles enabled by cooperative gold/scandium catalysis is presented, which facilitates the synthesis of 5-benzo[]carbazoles in moderate to excellent yields. This protocol features a broad substrate scope and good functional-group compatibility. Additionally, the resulting 5-benzo[]carbazoles exhibit good fluorescence properties, demonstrating the synthetic practicality of this method.

Diastereoselective Access to Seven-Membered Benzosultams via Palladium-Catalyzed Ring-Opening [3 + 2]-Annulation.

A palladium-catalyzed ring-opening [3 + 2]-annulation of spirovinylcyclopropanyl oxindoles with seven-membered cyclic -sulfonylimines has been developed. A wide range of seven-membered benzosultams featuring both a quaternary center and axially chiral biaryl scaffolds have been afforded in an average yield of 87% with moderate to excellent diastereoselectivities. The enantioenriched benzosultams were also accessed successfully in good yields with excellent atropoenantioselectivities enabled by the Pd(dba)/(,,)-SKP ligand.

Photothermal-driven disassembly of naphthalocyanine nano-photosensitizers for photothermal and photodynamic therapy.

The disassembly of nanomaterials is of particular interest for high-quality imaging and targeted therapies in the field of nanomedicine. In this study, we developed a novel strategy for fabricating self-assembled naphthalocyanine photosensitizers (SiNc@CEL) with intrinsically unique photochemical and photophysical properties. SiNc@CEL could be disassembled under the photothermal effect, and its photoactivity could be enhanced by 780 nm laser irradiation.

Synthesis and antitumor activity of some cholesterol-based selenocyanate compounds.

The introduction of selenium-containing functional groups into steroids to study the biological activities of related derivatives is rarely reported in the literature. In the present study, using cholesterol as raw material, four cholesterol-3-selenocyanoates and eight B-norcholesterol selenocyanate derivatives were synthesized, respectively. The structures of the compounds were characterized by NMR and MS.

Synergistic Sc(III)/Au(I)-Catalyzed Dearomative Spiroannulation of 2-(Ethynyl)aryl Cyclopropanes with 2-Aryl Indoles.

The diastereoselective assembly of spiroindolenines via a synergistic scandium/gold-catalyzed dearomative spiroannulation is herein described. This protocol offers access to a wide variety of spiroindolenine derivatives in 86% average yield with moderate to excellent diastereoselectivities (up to 97:3 dr). The control experimental studies lend support to the bimetallic relay catalysis.

Straightforward synthesis of steroidal selenocyanates through oxidative umpolung selenocyanation of steroids and their antitumor activity.

Straightforward access to steroidal selenocyanates in a single assembly step from steroids remains a significant challenge. However, the development of novel method for the synthesis of steroidal selenocyanates and further investigation of their bioactivities have largely lagged behind. In this work, selenocyano groups were directly introduced into the 17- or 21-position of pregnenolone, the 2-position of estradiol, and the 16-position of estrone.

Photoredox-catalysed chlorination of quinoxalin-2(1)-ones enabled by using CHCl as a chlorine source.

A photoredox-catalysed chlorination of quinoxalin-2(1)-ones was developed by using CHCl as a chlorine source, thus affording various 3-chloroquinoxalin-2(1)-ones in moderate to high yields. This protocol is characterized by mild reaction conditions, excellent regioselectivity, and readily available chlorination agent. Considering the operational simplicity and low cost of this chlorination approach, this developed method offers an innovative pathway for rapid incorporation of chlorine functionality into heteroarenes, and will inspire broader exploitation of new chlorination strategies.

Photoredox-Catalyzed Deoxygenation of Hexafluoroacetone Hydrate Enables Hydroxypolyfluoroalkylation of Alkenes.

An unprecedented photoredox-catalyzed phosphine-mediated deoxygenation of hexafluoroacetone hydrate was established to accomplish the hydroxylpolyfluoroalkylation of electron-deficient alkenes. A range of bis(trifluoromethyl)carbinols were facilely accessed by using readily available hexafluoroacetone hydrate, instead of toxic gaseous hexafluoroacetone. A range of electron-deficient alkenes are tolerated, giving the corresponding hydro-hydroxylpolyfluoroalkylated products in moderate to high yields.

Regioselective Access to Vicinal Diamines by Metal-Free Photosensitized Amidylimination of Alkenes with Oxime Esters.

A metal-free photosensitized protocol for regioselective diamination of alkene feedstocks over a single step was developed based on the rationally designed bifunctional diamination reagent, thus affording a range of differentially protected 1,2-diamines in moderate to high yields. Mechanistic studies reveal that the reaction is initiated with a triplet-triplet energy transfer between thioxanthone catalyst and diamination reagent, followed by fragmentation to simultaneously generate long-lived iminyl radical and transient amidyl radical. The excellent regioselectivity presumably stems from the large reactivity difference between two different N-centered radical species.

Photoredox-Catalyzed C-H Trideuteromethylation of Quinoxalin-2(1)-ones with CDCl as the "CD" source.

Herein, readily available and inexpensive CDCl was first identified as a new trideuteromethylation reagent under photoredox-catalyzed conditions. Thus, a facile photocatalytic protocol for the C-H trideuteromethylation of quinoxalin-2(1)-one was achieved. This operationally straightforward transformation displays a broad scope and provides a new route to introduce the trideuteromethyl group (CD) with excellent levels of deuterium content.

Rose bengal-modified gold nanorods for PTT/PDT antibacterial synergistic therapy.

In this study, Rose Bengal (RB) was loaded onto mesoporous silica coated gold nanorods (AuNR@SiO-NH) to form a novel multifunctional platform for antimicrobial therapy (AuNR@SiO-NH-RB). The platform combines the photothermal functions of AuNR and the photodynamic functions of RB to effectively inactivate bacteria under irradiation. Moreover, AuNR@SiO-NH-RB showed negligible cytotoxicity and good blood compatibility.

Photocatalyzed Defluorinative Dichloromethylation of α-CF Alkenes Using CHCl as the Radical Source.

A visible-light-induced defluorinative dichloromethylation of α-CF alkenes was developed with cheap and readily accessible chloroform simultaneously as a dichloromethylation reagent and reaction medium, leading to the facile preparation of new polyhalogenated scaffolds. Notably, the change from CHCl to CDCl offers a straightforward pathway for accessing the deuterated analogues with excellent degrees of D incorporation. Mechanistic studies suggested the reaction underwent a radical addition of the dichloromethyl radical with alkenes, followed by sequential single-electron transfer and defluorination.

Photoinduced Construction of a Benzothienopyridine--dioxide Framework Enabled by Polychloropyridyl Multifunctional Motifs.

Reported herein is a visible-light-induced, catalyst-free intramolecular cyclization of 4-phenylsulfonyl-2,3,5,6-tetrachloropyridine, leading to rapid assembly of a series of unprecedented benzo[4,5]thieno[3,2-]pyridine 5,5-dioxide scaffolds under mild conditions. The rational introduction of a perchloropyridin-4-yl module significantly facilitated this photoinduced process and offers a versatile platform for broad structural variation. Mechanistic studies revealed that a newly identified charge-transfer complex with carbonate is crucial to this photoinduced process.

Visible-Light-Induced, Palladium-Catalyzed 1,4-Difunctionalization of 1,3-Dienes with Bromodifluoroacetamides.

A highly modular 1,4-difunctionalization of 1,3-dienes with bromodifluoroacetamides and sulfinates/amines through a photoinduced palladium-catalyzed radical relay process is described herein. This developed protocol offers a facile and general route to access a variety of value-added CF-incorporated alkenes in moderate to good yields. The versatility and flexibility of this approach have been well illustrated by readily accessible starting materials, synthetic convenience, and wide functional group compatibility.

Photoredox-Catalyzed Cascade of Hydroxyarylenaminones to Access 3-Aminated Chromones.

Reported herein is a photoredox-catalyzed amination of hydroxyarylenaminones with -butyl ((perfluoropyridin-4-yl)oxy)carbamate, a versatile amidyl-radical precursor developed in our laboratory. This work establishes a new cascade pathway for the assembly of a range of 3-aminochromones under mild conditions. Downstream transformations of the obtained 3-aminochromones to construct diverse amino pyrimidines greatly broaden the applications of this photocatalyzed protocol.

Photodynamic and Photothermal Ce6-Modified Gold Nanorod as a Potent Alternative Candidate for Improved Photoinactivation of Bacteria.

The global rise of antibiotic resistance of pathogenic bacteria has become an increasing medical and public concern, which is further urging the development of antimicrobial channels for treating infectious diseases. The combination of photodynamic therapy (PDT) with photothermal therapy (PTT) has been considered as a promising alternative way for the replacement of traditional antibiotic therapy. In this research, the newly fabricated Chlorin-e6 (Ce6) conjugated mesoporous silica-coated AuNRs, designated AuNR@SiO-NH-Ce6, exhibited synergistic photothermal effects and single oxygen localized generation property, and showed stronger photoinactivation for bacteria compared with Ce6.

Visible-Light-Promoted Hydroxydifluoroalkylation of Alkenes Enabled by Electron Donor-Acceptor Complex.

A catalyst-free strategy for regioselective hydroxydifluoroalkylation of alkenes with alkyl bromides was developed, affording a series of difluoroalkylated tertiary alcohols in moderate to good yields. This photocatalyst-free protocol shows broad substrate scope under mild conditions. Moreover, mechanistic studies revealed that a newly identified electron donor-acceptor complex is crucial to this transformation.

Gold/scandium bimetallic relay catalysis of formal [5+2]- and [4+2]-annulations: access to tetracyclic indole scaffolds.

Regiodivergent formal [5+2]- and [4+2]-annulation reactions of indole derivatives with 2-(2-alkynyl)aryl cyclopropane-1,1-diesters (ACPs) have been developed. A series of tetracyclic indole derivatives were delivered in a 77% average yield with excellent regioselectivities enabled by Au(I)/Sc(III) bimetallic relay catalysis. A gram-scale reaction and further transformation of the resulting tetracyclic indoles demonstrated the practical utility of this protocol.

TBN-triggered, manipulable annulations of -hydroxyarylenaminones for divergent syntheses of oximinochromanones and oximinocoumaranones.

Divergent synthesis provides an indispensable route to rapid acquisition of structurally diverse chemical scaffolds from identical starting materials. Herein, we describe unprecedented divergent annulations of -hydroxyarylenaminones promoted by -butyl nitrite (TBN) under mild conditions. Two different types of benzo--heterocycle, including oximinochromanones and oximinocoumaranones, were smoothly assembled with a broad substrate scope and good functional group compatibility.

Electrochemical heterodifunctionalization of α-CF alkenes to access α-trifluoromethyl-β-sulfonyl tertiary alcohols.

An unprecedented electrochemical heterodifunctionalization of α-CF alkenes with benzenesulfonyl hydrazides was accomplished in this work, wherein a β-sulfonyl and a α-hydroxyl group were simultaneously incorporated across the olefinic double bond in a single operation. Consequently, a series of potentially medicinally valuable and densely functionalized α-trifluoromethyl-β-sulfonyl tertiary alcohols were assembled under mild conditions. Electrochemically-driven oxidative 1,2-difunctionlization of electron-deficient alkenes well obviates the need for oxidizing reagents, thus rendering this protocol more eco-friendly.

Visible-Light-Driven Sulfonation of α-Trifluoromethylstyrenes: Access to Densely Functionalized CF-Substituted Tertiary Alcohol.

Reported herein is a visible-light-induced sulfonation of α-trifluoromethylstyrenes with sodium sulfinates, which provides a series of α-trifluoromethyl-β-sulfonyl tertiary alcohols. This new synthetic protocol is enabled by a charge-transfer complex between oxygen and sulfinates, featuring broad substrate scope and scalability. Excellent functional group compatibility and chemoselectivity render this method suitable for sulfonation of pharmaceutically relevant molecules.