Visible Light-Assisted Ring-Opening of Cyclic Ethers with Carboxylic Acids Mediated by Triphenylphosphine and -Halosuccinimides.

The ring-opening of cyclic ethers (epoxide, oxetane, THF, and THP) by carboxylic acids was achieved by using -iodosuccinimide (NIS) or -bromosuccinimide (NBS) and triphenylphosphine under blue light. The corresponding ω-haloalkyl carboxylates were obtained under mild reaction conditions. The reaction is believed to work through a halogen bond complex between NIS (or NBS) and triphenylphosphine, which, upon irradiation with blue light, produces the key phosphine radical cation intermediate that initiates the ring-opening reactions.

Organocatalytic synthesis of β-enaminyl radicals as single-electron donors for phenyliodine(III) dicarboxylates: direct one-pot alkylation-aminoxidation of styrenes.

A direct one-pot alkylation-aminoxidation of styrene derivatives was achieved using -generated alkyl and -oxyl radicals. The corresponding -alkylated hydroxylamine derivatives were obtained in moderate to good yields. The reaction features the generation of the alkyl radicals from phenyliodine(III) dicarboxylates an organocatalytic process, the use of phenyliodine(III) dicarboxylates as the source of the alkyl radicals and oxidants for the generation of -oxyl radicals, and the first generation of the β-enaminyl radicals a HAT process and their use as single-electron donors.

Oxa-Nazarov Cyclization-Michael Addition Sequence for the Rapid Construction of Dihydrofuranones.

The Nazarov cyclization has been established as a powerful tool in constructing cyclopentenone skeletons. In sharp contrast, oxa-Nazarov cyclization that affords dihydrofuranones, a new type of product, has been less explored. In this work, we report the I-catalyzed oxa-Nazarov cyclization-Michael addition cascade between vinyl α-diketones and enones.

Visible light-assisted organocatalytic α-acyloxylation of ketones using carboxylic acids and -halosuccinimides.

The α-acyloxylcarbonyl motif can be found in many important pharmaceuticals and biologically active natural products and their derivatives. In this manuscript, the direct synthesis of α-acyloxylketones from ketones and readily available carboxylic acids was realized using a photo-assisted halogen bond-mediated organocatalytic α-acyloxylation reaction. The desired α-acyloxylation products were obtained in good to high yields.

Domino Michael/Michael reaction catalyzed by switchable modularly designed organocatalysts.

The domino Michael/Michael reaction between ()-7-aryl-7-oxohept-5-enals and -cinnamaldehydes was investigated by using modularly designed organocatalysts (MDOs). It was found that both the enamine and iminium catalytic modes of the MDOs are switchable and can be individually switched on and off by using appropriate combinations of the precatalyst modules and the reaction conditions. When both the enamine and iminium catalysis modes of the MDOs are switched on, the desired domino reaction products can be obtained in good yields and stereoselectivities under optimized conditions.

Diastereodivergent synthesis of 4-oxocyclohexanecarbaldehydes by using the modularly designed organocatalysts upon switching on their iminium catalysis.

The cinchona thiourea moiety in the self-assembled modularly designed organocatalysts (MDOs) switches off the iminium catalysis of these catalysts. In this study, it was found that the inhibited iminium catalysis could be switched on by using an appropriate weak acid and that, once the iminium catalysis was switched on, these catalysts could be applied for the highly stereoselective and diastereodivergent synthesis of 4-oxocyclohexanecarbaldehydes via a domino reaction between ketones and α,β-unsaturated aldehydes.

Catalytic Annulation of Alkynyl 1,2-Diketone Leading to Hydroxy Spirocyclopenteneindenedione: An Organic Dye with Strong Crystallization-Induced Emission and Data Storage Application.

An unprecedented cascade annulation between alkynyl 1,2-diketones and indene-1,3-diones is achieved for the first time, leading to a series of propeller-like large conjugated compounds in ≤99% yield. The products show strong crystallization-induced emission, with the colors changing from green to red. The fluorescence of the dye can be switched on and off by external acid/alkali stimuli, which can be utilized to develop a practical technology for rewritable information storage and security ink.

Regioselectivity-Switchable Catalytic Annulations of Alkynyl α-Diketones and α-Cyanoketones.

Regioselectivity-switchable reactions hold irreplaceable importance in the construction of diversified architectures. In this work, Brønsted base-catalyzed regioselectivity-switchable annulations between alkynyl α-diketones and α-cyanoketones have been achieved for the first time, delivering a series of skeletally thoroughly different dihydrofurofuran and furan derivatives. A range of novel transformations of the products can be realized.