Transition-metal- and oxidant-free three-component reaction of quinoline <i>N</i>-oxides, sodium metabisulfite and aryldiazonium tetrafluoroborates <i>via</i> a dual radical coupling process

You, Guirong; Xi, Dan Li; Sun, Jian; Hao, Liqiang; Xia, Chengcai

doi:10.1039/c9ob02106j

Cited by 30 publications

(18 citation statements)

References 144 publications

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“…isoquinolines 42 (Scheme 33). 57 In this approach, aryldiazonium tetrafluoroborates bearing p-substituents were more efficient than those bearing m-and o-substituents. This might be due to steric effects.…”

Section: Review Synopenmentioning

confidence: 94%

The Renaissance of Alkali Metabisulfites as SO2 Surrogates

Patel¹,

Sahoo²,

Dahiya³

et al. 2021

SynOpen

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The upsurge of interest in the development of methodologies for the construction of sulfur-containing compounds via the use of expedient reagents has been established as sustainable tools in organic chemistry. This review focuses on the sulfonylation reactions using inorganic sulfites (Na2S2O5 or K2S2O5) as the sulfur dioxide surrogate. Unlike bis-adduct of DABCO, which is an excellent surrogate of the gaseous SO2, the use of sodium or potassium metabisulfites as SO2 surrogates are equally efficient. The objective of the current review is to bring out the latest collection of sulfonylation reactions using inorganic sulfites. For better understanding, the review is categorized according to the mode of reactions viz., transition metal-catalyzed SO2 insertion, metal-free SO2 insertion, and visible light-mediated SO2 insertion. All the reactions in each of the sections are depicted with selected examples with a pertinent explanation of the proposed mechanism. Nevertheless, based on the biological relevance of sulfonylated compounds the use of inorganic sulfites as the SO2 source in various sulfonylation reactions are needed to be explored.

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Section: Review Synopenmentioning

confidence: 94%

The Renaissance of Alkali Metabisulfites as SO2 Surrogates

Patel¹,

Sahoo²,

Dahiya³

et al. 2021

SynOpen

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“…Xia's group developed a three‐component sulfonylation using quinoline N ‐oxides, sodium metabisulfite, and aryldiazonium tetrafluoroborates 172 to provide C2‐sulfonylated products 169 in moderate to good yields (Scheme 52). [77] The aryldiazonium tetrafluoroborates decompose to generate an aryl radical, which subsequently attacks Na 2 S 2 O 5 to give sulfonyl radical 149 .…”

Section: Simple C2‐h‐functionalizationmentioning

confidence: 99%

Recent Advances in the Synthesis of C2‐Functionalized Pyridines and Quinolines Using N‐Oxide Chemistry

et al. 2020

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While remarkable progress has recently been made for the direct C−H‐functionalization of azines, its application is still limited by a lack of accessible functional groups (primarily carbon‐based) and poor regioselectivity. In contrast, C2‐functionalized pyridines and quinolines can be easily synthesized by treating readily available N‐oxides with various reagents under appropriate activation conditions. This review seeks to comprehensively document the available synthetic methods for introducing functional groups at the C2 position of pyridines and quinolines. In this work, we highlight recent developments in the C2‐functionalization of pyridine and quinoline N‐oxides and address both the mechanisms and regioselectivity of the reactions. We also describe the pathways and reactive species involved in these processes and highlight a number of medically relevant nitrogen heteroaromatics.

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“…Initially, visible-light-excitation of Na 2 ⋅ eosin Y generated Na 2 ⋅ eosinY*. In the next step, singleelectron-transfer (SET) from sulfinic acid to Na 2 ⋅ eosinY* produced the sulfonyl radical cation 72 and Na 2 ⋅ eosinY Transition-metal and oxidant-free C-2 sulfonylation of quinoline N-oxide was discussed by Xia and co-workers [50] in 2019. Treatment of quinoline N-oxides 18 with aryldiazonium tetrafluoroborates in the presence of sodium metabisulfite in DCE at 50°C delivered the desired 2-sulfonylquinolines 75 (Scheme 28).…”

Section: Transition Metal Free αà Cà S Bond Formation Of Six Memberedmentioning

confidence: 99%

“…Transition‐metal and oxidant‐free C‐2 sulfonylation of quinoline N ‐oxide was discussed by Xia and co‐workers [50] in 2019. Treatment of quinoline N ‐oxides 18 with aryldiazonium tetrafluoroborates in the presence of sodium metabisulfite in DCE at 50 °C delivered the desired 2‐sulfonylquinolines 75 (Scheme 28).…”

Section: Introductionmentioning

confidence: 99%

Transition Metal Free α−C−H Functionalization of Six Membered Heteroaromatic‐N‐Oxides

et al. 2021

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A comprehensive account of transition metal free αÀ CÀ H functionalization of six membered heteroaromatic-N-oxides has been discussed in this review article. This review includes brief account of explanatory text with schemes, effect of substituents on the reaction and limitation of reaction for transition metal free αÀ CÀ H functionalization of six membered heteroaromatic-N-oxides. Schemes depict the reaction conditions along with a quick look into their mechanism. Each of the reported example has been considered for reacting substrates such as readily available different six membered heteroaromatic-N-oxides, activating reagents, reaction conditions and different types of nucleophiles (N, Halogens, P, S, C and O), reaction conditions and reagents used for transition metal free αÀ CÀ H functionalization of six membered heteroaromatic-Noxides. This review will be supportive to the chemists in understanding the challenges associated with the reported methods as well as the future potentials, both in the choice of substrates and reagents.

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Transition-metal- and oxidant-free three-component reaction of quinoline N-oxides, sodium metabisulfite and aryldiazonium tetrafluoroborates via a dual radical coupling process

Abstract: Synthesis of 2-sulfonylquinolines via a three-component reaction of quinoline N-oxides, sodium metabisulfite, and aryldiazonium tetrafluoroborates under transition-metal- and oxidant-free conditions.

Cited by 30 publications

References 144 publications

The Renaissance of Alkali Metabisulfites as SO2 Surrogates

The Renaissance of Alkali Metabisulfites as SO2 Surrogates

Recent Advances in the Synthesis of C2‐Functionalized Pyridines and Quinolines Using N‐Oxide Chemistry

Transition Metal Free α−C−H Functionalization of Six Membered Heteroaromatic‐N‐Oxides

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