A Type of Stable Amides Behaves as Acyl Transfer Reagents upon Visible-Light Irradiation through Self-Aromatization.

Organic molecules with light-modifiable reactivity are important in many fields because they can serve as the "switch" for light to trigger chemical processes. Herein, we disclose a new type of stable non-twisted amides, the reactivity of which can be turned on by light as acyl transfer reagents. Upon photo-activation, these amides react with various nucleophiles including amines, phenols, hydroxide, thiols, boronic acids, and alkynes either under metal-free or metal-catalysis conditions. This reactivity hinges on the design and synthesis of a photo-activatable reagent (7-nitro-5,6-dihydrophenanthridine), which undergoes self-aromatization enabled by an internal oxidant under light. This masked acyl donor group is anticipated to be useful in scenarios where light is preferred to trigger a chemical process.

Selective Hydrolysis of Primary and Secondary Amides Enabled by Visible Light.

Amide hydrolysis is a fundamentally important transformation in organic chemistry. Developing hydrolysis procedures under mild conditions with a broad substrate scope is desirable. Herein, by leveraging a photoresponsive auxiliary o-nitroanilide, we established a mild two-step protocol for the hydrolysis of primary and secondary amides. This protocol is driven by visible light irradiation at room temperature under neutral conditions, which tolerates numerous acid- and base-sensitive functional groups. Various drugs, natural product-, and amino acid-derived amides can be selectively hydrolyzed.

Synthesis of 1-Aminoisoquinolines and Their Application in a Host-Guest Doped Strategy To Construct Ultralong Room-Temperature Phosphorescence Materials for Bioimaging.

Organic ultralong room-temperature phosphorescence (RTP) materials have attracted great attention for their wide applications in optoelectronic devices and bioimaging. However, the development of these materials remains a challenging task, partially due to the lack of rational molecular design strategies and unclear luminescence mechanisms. Herein, we present a method for facile access to structurally diverse substituted 1-aminoisoquinoline derivatives through a copper-catalyzed one-pot three-component coupling reaction that provides a promising approach to rapidly assemble a library of 1-aminoisoquinolines for exploring the regularity of the host-guest doped system. A series of host-guest RTP materials with wide-ranging lifetimes from 4.4 to 299.3 ms were constructed by doping various substituted isoquinolines derivatives into benzophenone (BP). Furthermore, 4 r/BP nanoparticles could be used for in-vivo imaging with a signal-to-noise ratio value as high as 32, revealing the potential of the isoquinoline framework for the construction of high-performance RTP materials.

Simple and Practical Conversion of Benzoic Acids to Phenols at Room Temperature.

Phenols are important organic molecules because they have found widespread applications in many fields. Herein, an efficient and practical approach to prepare phenols from benzoic acids via simple organic reagents at room temperature is reported. This approach is compatible with various functional groups and heterocycles and can be easily scaled up. To demonstrate its synthetic utility, bioactive molecules and unsymmetrical hexaarylbenzenes have been prepared by leveraging this transformation as strategic steps. Mechanistic investigations suggest that the key migration step involves a free carbocation instead of a radical intermediate. Considering the abundance of benzoic acids and the utility of phenols, it is anticipated that this method will find broad applications in organic synthesis.

Synthesis of 3-Selenylindoles through Organoselenium-Promoted Selenocyclization of 2-Vinylaniline.

A novel metal-free one-pot protocol for the synthesis of potential biologically active molecules 3-selenylindoles via intramolecular cyclization/selenylation with simple 2-vinylaniline has been developed with moderate to good yield, thus representing it as a facile route to diverse substitution patterns around the indole core. The reaction proceeded smoothly with a broad substrate scope and excellent functional group tolerance. Moreover, the present synthetic route could be readily scaled up to gram quantity without difficulty. Mechanistic studies have revealed that in situ formed selenium electrophile species may be the key intermediate for the selenocyclization process.

Palladium-Catalyzed Cascade Reactions of 2-(Cyanomethoxy)chalcones with Arylboronic Acids: Selective Synthesis of Emissive Benzofuro[2,3-c]pyridines.

The Pd(II)-catalyzed cascade reactions of 2-(cyanomethoxy)chalcones with arylboronic acids were demonstrated, allowing the rapid construction of benzofuro[2,3-c]pyridine skeletons with excellent selectivity. These transformations involve the domino-style formation of C-C/C-C/C-N bonds through nitrile carbopalladation, intramolecular Michael addition, cyclization, and aromatization. This chemistry allows for the reactions of 2-(cyanomethoxy)chalcones with thiophen-3-ylboronic acid, providing 3-aryl-1-(thiophen-3-yl)benzofuro[2,3-c]pyridines in moderate to good yields. In addition, the resulting products represent a new class of emissive fluorophores.

A highly selective and reversible fluorescence "OFF-ON-OFF" chemosensor for Hg2+ based on rhodamine-6G dyes derivative and its application as a molecular logic gate.

A new rhodamine-6G-based chemosensor X was designed and synthesized for the colorimetric and fluorometric detection of Hg2+. The chemosensor X responsed to Hg2+ had good sensitivity, high selectivity and excellent reversibility in HEPES buffer (10 mM, pH 7.4)/CH3CN (40:60, V/V). The recognition mechanism of X toward Hg2+ was evaluated by Job's plot, IR and MS. Meanwhile, X-Hg2+ fluorescence lifetime was also measured. It was interesting that X displayed favorable reversibility to form an "off-on-off" type signaling behavior with the Hg2+-induced emission spectra being quenched by I-. Furthermore, it could be applied as a molecular logic gate and test strips based on X exhibited a good reversibility selectivity to Hg2+.