論文

The synergy of an Ir-based photosensitizer with mild oxidizing ability and a thiol catalyst enables efficient allylic C-H functionalization of enol silyl ethers with imines under visible light irradiation. Subsequent transformations of the aminoalkylated enol silyl ethers allow for the facile construction of unique molecular frameworks such as functionalized octahydroisoindol-4-one.

Selective reactions between more than two molecules are governed by appropriate combinations of polar functionalities. This restriction can be ameliorated by photoredox umpolung reactivity, which enables the functionalization of unreactive bonds of chemical reagents while leaving their inherent reactive functional groups intact, paving the way for otherwise difficult multicomponent reactions. Here we report that the photocatalytic single-electron oxidation of phosphorus ylides underpins their sequential assembly with electron-rich olefins and α,β-unsaturated carbonyl compounds to form functionalized six-membered carbocycles. This three-component formal cycloaddition, featuring consecutive C–H functionalization and Wittig reaction of phosphorus ylides, offers a carbyne-like transformation that involves the conversion of inert C–H and C=P bonds into C–C and C=C bonds, respectively, as a powerful tool for the rapid construction of versatile synthetic building blocks from readily available substrates. (Figure presented.)

Thioamidate ions are introduced as competent cocatalysts for multisite proton-coupled electron transfer (MS-PCET) catalysis. The effectiveness of these anions is ascribed to the high pKa values of their conjugate acids. The combined use of bench-stable tetrabutylammonium thioamidate with an appropriate Ir-based photosensitizer allows the CH alkylation of a range of CH donors, including simple cyclic alkanes, under visible-light irradiation.

The development of catalytic systems that facilitate simple yet valuable molecular transformations in a sustainable manner is of fundamental importance in the field of synthetic organic chemistry. Herein, we report the expedient application of a zwitterionic acridinium amidate, a recently developed direct hydrogen-atom-transfer catalyst, in catalytic acceptorless dehydrogenation (CAD). The combined use of the acridinium amidate with a cobaloxime complex and a protic additive as a catalyst system enables the CAD of hydrocarbons to proceed with high efficiency under mild reaction conditions.

The development of small organic molecules that can convert light energy into chemical energy to directly promote molecular transformation is of fundamental importance in chemical science. Herein, we report a zwitterionic acridinium amidate as a catalyst for the direct functionalization of aliphatic C−H bonds. This organic zwitterion absorbs visible light to generate the corresponding amidyl radical in the form of excited-state triplet diradical with prominent reactivity for hydrogen atom transfer to facilitate C−H alkylation with a high turnover number. The experimental and theoretical investigations revealed that the noncovalent interactions between the anionic amidate nitrogen and a pertinent hydrogen-bond donor, such as hexafluoroisopropanol, are crucial for ensuring the efficient generation of catalytically active species, thereby fully eliciting the distinct reactivity of the acridinium amidate as a photoinduced direct hydrogen atom transfer catalyst.

The chemical and physical properties of amides change substantially when the electron-withdrawing groups attached to the nitrogen are varied. Herein, we report the superior performance of N-diphenylphosphinyl 1,2,3-triazolium amidate as a photoinduced hydrogen-atom transfer catalyst compared to its N-benzoyl analog. A binary catalyst system of the phosphinyl amidate and an Ir-based photocatalyst enables the alkylation of unbiased C-H bonds.