A Polyniobotungstate-Based Hybrid for Visible-Light-Induced Phosphorylation of N-Aryl-Tetrahydroisoquinoline

Phototriggered Self-Catalyzed Phosphorylation of 3,4-Dihydroquinoxalin-2(1H)-ones with Diarylphosphine Oxides in EtOH

A highly effective external photocatalyst- and additive-free method for the phosphorylation of 3,4-dihydroquinoxalin-2(1H)-ones to produce phosphorylated dihydroquinoxalin-2(1H)-ones has been reported. A wide variety of phosphorylated products were formed in good to excellent yields. Preliminary mechanistic studies reveal that the phosphorylation process involves an EnT process, a SET process, a HAT process, and a deprotonation process.

Synthetic Methods for Azaheterocyclic Phosphonates and Their Biological Activity: An Update 2004-2024

The increasing importance of azaheterocyclic phosphonates in the agrochemical, synthetic, and medicinal field has provoked an intense search in the development of synthetic routes for obtaining novel members of this family of compounds. This updated review covers methodologies established since 2004, focusing on the synthesis of azaheterocyclic phosphonates, of which the phosphonate moiety is directly substituted onto to the azaheterocyclic structure. Emphasizing recent advances, this review classifies newly developed synthetic approaches according to the ring size and providing information on biological activities whenever available. Furthermore, this review summarizes information on various methods for the formation of C-P bonds, examining sustainable approaches such as the Michaelis-Arbuzov reaction, the Michaelis-Becker reaction, the Pudovik reaction, the Hirao coupling, and the Kabachnik-Fields reaction. After analyzing the biological activities and applications of azaheterocyclic phosphonates investigated in recent years, a predominant focus on the evaluation of these compounds as anticancer agents is evident. Furthermore, emerging applications underline the versatility and potential of these compounds, highlighting the need for continued research on synthetic methods to expand this interesting family.

Photocatalytic Reduction of Nitrobenzene to Aniline by an Intriguing {Ru(C6H6)}-Based Heteropolytungstate

In this paper, we have successfully synthesized a structurally novel heteropolytungstate via coordination of four {Ru(C6H6)} and trivacant {TeW9O33} clusters, formulated as Cs4Na2H2[Te2W20O72(H2O){(C6H6)Ru}4]·12H2O (1). Compound 1 inherited the strong absorption of [Ru(C6H6)Cl2]2 in the visible region and {TeW9O33} in the UV region, providing a good basis for photocatalysis. As expected, compound 1 showed good photocatalytic activity in the visible-light-driven reduction of nitrobenzene using N2H4·H2O as a reductant with a yield of 99.8%, a high turnover number (TON = 330), and a high turnover frequency (TOF = 24 h-1). The cyclic experiment of nitrobenzene reduction indicated that compound 1 was an effective and stable heterogeneous catalyst. Finally, the nitrobenzene reduction pathway was affirmed using condensation with azobenzene as a reaction intermediate based on control experiments.

Visible-Light-Induced Highly Site-Selective Direct C-H Phosphorylation of Pyrrolo[2,3-d]pyrimidine Derivatives with H-Phosphine Oxides

An efficient and highly regioselective C6-phosphorylation protocol for pyrrolo[2,3-d]pyrimidine (7-DAP) derivatives with various H-phosphine oxides induced by visible light at room temperature is described for the first time. This protocol has been successfully achieved by the combination of Na2-eosin Y as a photocatalyst and LPO as an oxidant under transition metal- and additive-free conditions. The broad substrate scope, good functional group tolerance, excellent regioselectivity, and air tolerant conditions make this process favorable for the functional modification of pyrrolo[2,3-d]pyrimidine scaffold and enrich the phosphorylated 7-DAP compounds for further biological evaluation.

Fabrication of Polyoxometalate-Based Metal-Organic Frameworks Integrating Paddlewheel Rh2(OAc)4 for Visible-Light-Driven Oxidative Coupling of Amines

The development of visible-light-responsive, environmentally friendly, and reusable photocatalysts for organic oxidation reactions is of vital significance. Herein, four polyoxometalate-based metal-organic frameworks (POMOFs) were synthesized and systematically characterized by assembling the paddlewheel complex Rh2(OAc)4 and various polyoxometalates (POMs). Single-crystal X-ray diffraction analysis revealed that the four POMOFs were isomorphic and possessed rare structural features among the POMOFs, with POMs as nodes and Rh2(OAc)4 as linkers. As expected, the activities of the four POMOFs for the photocatalytic oxidative coupling of benzylamine were better than that of Rh2(OAc)4 or POMs individually, which was ascribed to the synergistic effect between them, and the intrinsic reasons for the difference in the activity were explained via electrochemical measurements. In particular, the product imine yield reached 96.1% with NaRh-SiW12 as the catalyst and a turnover number and a turnover frequency of 480.5 and 120.5 h-1, respectively, while the product yield remained as high as 92% after three repetitions, evidencing its high stability. Moreover, the higher activities of the four POMOFs for the selective epoxidation of various alkenes reaffirm the synergistic effect between Rh2(OAc)4 and POMs.

Access to Phosphine-Containing Quinazolinones Enabled by Photo-Induced Radical Phosphorylation/Cyclization of Unactivated Alkenes

A mild and facile photo-induced cascade radical addition/cyclization of unactivated alkenes has been reported, through which a variety of biologically valuable phosphine-containing quinazolinones could be obtained in moderate to good yields. The protocol was characterized by mild conditions, broad substrate scope, and high atomic economy.