Oxone-Promoted Synthesis of 4-(Chalcogenyl)isoquinoline-N-oxides from Alkynylbenzaldoximes and Diorganyl Dichalcogenides

Abstract

We report a protocol for the synthesis of 3-organyl-4-(organylchalcogenyl)­isoquinoline-2-oxides via electrophilic cyclization between alkynylbenzaldoximes and diorganyl dichalcogenides promoted by Oxone. A total of 21 3-organyl-4-(organylchalcogenyl)­isoquinoline-2-oxides were selectively obtained in yields of up 93% under an ultrasound irradiation condition in short reaction times (10–70 min). Additionally, the synthetic usefulness of the 3-phenyl-4-(phenylselanyl)­isoquinoline-2-oxide was demonstrated in the annulation reaction with 1-(2-bromophenyl)-3-phenylprop-2-yn-1-one and in the deoxygenation reaction with phenylboronic acid.

“Green Is the Color”: An Update on Ecofriendly Aspects of Organoselenium Chemistry

“…Employing the system (R 1 Se) 2 6 /Oxone ® , Perin and co-workers have reported, in 2021, an electrophilic cyclization of alkynylbenzaldoximes 37 under ultrasound irradiation to construct 3-organyl-4-(organylselanyl)isoquinoline-2-oxides 38 [ 40 ]. The reactions were conducted in the presence of ethanol, and a wide range of substrates (electron-rich and electron-deficient) were satisfactorily employed, affording the desired products 38 in good to excellent yields, in just few minutes.…”

“…In the sequence, the oxime 37 reacts with the electrophilic spe III and IV', to result in the seleniranium intermediate V. Finally, a dehydrogenative tramolecular annulation drives the reaction to the desired product 38 (Scheme 16). Employing the system (R 1 Se) 2 6/Oxone ® , Perin and co-workers have reported, in 2021, an electrophilic cyclization of alkynylbenzaldoximes 37 under ultrasound irradiation to construct 3-organyl-4-(organylselanyl)isoquinoline-2-oxides 38 [40]. The reactions were conducted in the presence of ethanol, and a wide range of substrates (electron-rich and electron-deficient) were satisfactorily employed, affording the desired products 38 in good to excellent yields, in just few minutes.…”

Applications of Oxone® in Organic Synthesis: An Emerging Green Reagent of Modern Era

“…Remarkably, N ‐heterocycles have attracted a tremendous attention of the research community worldwide because of their utility in medicinal chemistry, supramolecular chemistry, biological sciences, drug discovery and development etc. Among the uncountable N ‐heterocyclic systems, pyrazole ring is found in a myriad of vital natural and non‐natural products in addition to its presence in some important commercial drugs [335–340] . In that context, Perin et al .…”

Recent Advances in the Oxone-Mediated Synthesis of Heterocyclic Compounds

“…In general, several para-methoxyl alkynyl-N-phenylimines 37 were satisfactorily submitted to the optimized reaction conditions, tolerating a wide range of substituents, including aryl systems bearing electron-donating and -withdrawing groups, heteroaryl and alkyl (Scheme 26). In 2021, some of us reported the Oxone/RSeSeR-promoted electrophilic 6-endo-dig cyclization of alkynylbenzaldoximes 39, to access 3-organyl-4-(organylchalcogenyl)isoquinoline-2-oxides 40 (Scheme 27) [31]. The process was conducted under ultrasound irradiation in the presence of EtOH as promoting reaction medium, affording twenty-one Se-containing N-oxides 40 at good to excellent yields, within just a few minutes of reaction.…”