Visible-Light-Induced Oxyalkylation of 1,2,4-Triazine-3,5(2H, 4H)-diones with Ethers via Oxidative Cross-Dehydrogenative Coupling

Abstract

An efficient and convenient method to synthesize 6-oxyalkylated 1,2,4-triazine-3,5­(2H, 4H)-diones has been developed via visible-light-induced cross-dehydrogenative coupling reaction between 1,2,4-triazine-3,5­(2H, 4H)-diones and ethers with a wide range of functional group tolerance. The present transformation employs the cheap and low-toxic 2-tert-butylanthraquinone as a metal-free photocatalyst and air as a green oxidant at room temperature. Moreover, this reaction can also be driven by sunlight as a clean energy resource. The synthetic utility of this method is further demonstrated by gram-scale reaction and application in the preparation of key intermediates of bioactive molecules.

Alkyl radicals from diacyl peroxides: metal-/base-/additive-free photocatalytic alkylation of N-heteroaromatics

“…16 Numerous synthetic procedures on the functionalization of N -heteroaromatics, including alkylation, 17 acylation, 18 arylation, 19 alkoxylation, 20 and other processes, 21 have been developed during the past few decades. 22 Particularly, the direct C–H functionalization of azauracils has gained huge attention recently using sulfur ylides, 23 1,4-dihydropyridines (DHPs), 24 N -alkyl- N -methyl anilines or ethers, 25 and N -(acyloxy)pthalimides (NHPI esters) 26 as alkylating reagents, respectively. However, the metal-free photocatalytic system at room temperature employing alkyl diacyl peroxides as alkyl radical sources has never been established so far.…”

Recent Advances in Aerobic Oxidative of C−H Bond by Molecular Oxygen Focus on Heterocycles

“…Zhang and zhao developed a visible‐light‐induced approach for the synthesis of 6‐oxyalkylated 1,2,4‐triazine3,5(2H,4H)‐diones ( 129 ) via 2‐ t ‐Bu‐AQN‐catalyzed cross cross‐dehydrogenative using 1,2,4‐triazine‐3,5(2H,4H)‐diones ( 127 ) and ethers ( 128 ) as coupling partner in the air condition(Scheme 26). [47] In addition, the reaction can be scaled up to the gram level and the obtained key intermediate of bioactive molecules in one step, which could be converted into Azazauracil AzT ( 130 ) as an HIV‐1 RT inhibitor through a click reaction, demonstrating the practicality of the synthesis method.…”

Rose‐Bengal‐Photocatalyzed Cross‐Dehydrogenative Coupling Reactions under Visible Light

“…[69][70][71][72] Rose bengal is a photocatalyst that has proven to be highly versatile in numerous organic transformations. [68,[73][74][75][76][77][78][79][80][81] Rose bengal (RB), are non-toxic, [82] and strongly absorb visible light of wavelength 480-550 nm (green region), making them one of the most relevant tools for synthetic chemists. [83,84] Furthermore, removing RB from crude mixtures can be challenging and may result in unintended side reactions, which are significant limitations in sustainable synthesis.…”

“…Rose bengal is a photocatalyst that has proven to be highly versatile in numerous organic transformations. Table 1 compares it′s photocatalytic capabilities to other photocatalysts [68,73–81] . Rose bengal (RB), are non‐toxic, [82] and strongly absorb visible light of wavelength 480–550 nm (green region), making them one of the most relevant tools for synthetic chemists [83,84] .…”