Persulfate-activated charcoal mixture: an efficient oxidant for the synthesis of sulfonated benzo[d][1,3]oxazines from N-(2-vinylphenyl)amides and thiols in aqueous solution

Abstract

A simple method for the synthesis of 2,4-aryl-4-((arylsulfonyl)methyl)-4H-benzo[d][1,3]oxazines using an easily accessible K2S2O8-activated charcoal mixture and thiols, respectively, as an oxidant and sulfonylating precursors has been described.

2‐Arylbenzyl Methyl Ethers as Precursors for the Tandem Synthesis of Benzo[c]coumarins Over Heterogeneous Visible‐Light Photoredox Catalysis with Graphitic Carbon Nitride (g‐C3N4)

“…It is important to note that bisulfate solutions are acidic in nature and are known to promote ester hydrolysis. [25,26] On the basis of control experiments as well as literature reports, a plausible reaction mechanism is proposed in Scheme 3. The visible-light excitation results in the effective separation of photogenerated electron-hole pairs of g-C 3 N 4 with a band gap of 2.7 eV.…”

“…Later, when 2‐(methoxymethyl)‐1,1′‐biphenyl ( 1 a ) was exposed to radiation in the absence of (NH 4 ) 2 S 2 O 8 under the optimized reaction conditions, a mixture of [1,1′‐biphenyl]‐2‐carboxylic acid, methyl [1,1′‐biphenyl]‐2‐carboxylate, and 6H‐benzo[c]chromen‐6‐one were obtained (Scheme 2), suggesting that the (NH 4 ) 2 S 2 O 8 is necessary for the complete conversion of [1,1′‐biphenyl]‐2‐carboxylic acid into 6H‐benzo[c]chromen‐6‐one as well as hydrolysis of methyl [1,1′‐biphenyl]‐2‐carboxylate. It is important to note that bisulfate solutions are acidic in nature and are known to promote ester hydrolysis [25,26] …”

“…[7][8][9][10] Furthermore, the combined use of the g-C 3 N 4 photoredox catalyst with 2-arylbenzyl methyl ethers may result in the production of exceptionally valuable benzo[c]coumarins (Scheme 1) under the eco-friendly conditions. As part of our research works on the persulfate activation by carbonaceous materials, [25,26] herein, we disclose three reactions (oxidation, hydrolysis and dehydrogenative lactonization) in one-pot approach for the synthesis of benzo[c]coumarins from 2arylbenzyl methyl ethers using g-C 3 N 4 as a heterogeneous catalyst under blue LEDs irradiation (Scheme 1, right). A feasible reaction mechanism has also been described.…”

Recent trends in the applications of sonochemical reactors as an advanced oxidation process for the remediation of microbial hazards associated with water and wastewater: A critical review

“…The widespread use of PMS for sterilization makes it more appropriate for the microbial breakdown of contaminants. APS is not a favoured option in other PS applications since it may disintegrate to produce ammonia, although it has more advantages in material modification or metal extraction [24] .…”

Synthesis of gem-dibromo 1,3-oxazines by NBS-mediated electrophilic cyclization of propargylic amides

“…9 Thus, considerable efforts have been made to develop efficient strategies for constructing these skeletons, especially functionalized 1,3-oxazine derivatives. 10–12 It is worth noting that the functionalization of 1,3-oxazines could alter the biological and physical properties of the parent molecules. Therefore, the simultaneous introduction of the gem -dibromide functional group and 1,3-oxazine into one molecular skeleton could yield various dibrominated 1,3-oxazines, providing a platform to modify the corresponding biological activity of the parent molecules.…”