scholarly journals The renaissance of alkali metabisulfites as SO2 surrogate

SynOpen ◽  
2021 ◽  
Author(s):  
Bhisma Patel ◽  
Ashish Kumar Sahoo ◽  
Anjali Dahiya ◽  
Amitava Rakshit
Keyword(s):  
Organic Chemistry ◽  
Sulfur Dioxide ◽  
Transition Metal ◽  
Visible Light ◽  
Metal Free ◽  
Biological Relevance ◽  
Current Review ◽  
Metal Catalyzed ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

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.

Visible-light promoted one-pot synthesis of sulfonated spiro[4,5]trienones from propiolamides, anilines and sulfur dioxide under transition metal-free conditions

2019 ◽  
Vol 55 (81) ◽  
pp. 12212-12215 ◽  
Author(s):  
Yu Liu ◽  
Qiao-Lin Wang ◽  
Zan Chen ◽  
Quan Zhou ◽  
Bi-Quan Xiong ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Transition Metal ◽  
Visible Light ◽  
Aromatic Amines ◽  
One Pot ◽  
Metal Free ◽  
One Pot Synthesis

A novel visible-light promoted sulfonylation/ipso-cyclization of N-arylpropiolamides with aromatic amines and DABCO·(SO2)2 to synthesize various sulfonated spiro[4,5]trienones is reported.

scholarly journals Lewis Acid-Activated 8-Quinolinethiosulfonates: An Efficient Methodology for CS(alkyl) Bond Formation

2020 ◽  
Author(s):  
erwan galardon
Keyword(s):  
Lewis Acid ◽  
Bond Formation ◽  
The Other ◽  
Sulfinic Acid ◽  
Metal Free ◽  
Noble Metal Catalysts ◽  
Large Pool ◽  
Metal Catalyzed ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

The importance of sulfur-containing compounds in various fields, ranging from material science1-2 to medicinal chemistry, 3 has called for the development of synthetic strategies to form carbon-sulfur (C-S) bonds. Thus, numerous approaches based on the nucleophilicity of thiols have been designed over the years, which mostly use air-sensitive noble metal catalysts.4- 9 At the opposite, the use of electrophilic sulfur reagents is also a powerful, more eco-friendly approach, in particular for the sulfenylation of C-H bonds into C-S bonds.10-11 In this context, the sulfenylation of indoles (Equation 1) has become a benchmark reaction to develop and test new sulfenyl transfer reagents, because indoles are good nucleophiles and their occurrence in many natural products or biological active compounds makes them attractive synthetic targets.12-14 For instance, metal-catalyzed or metal-free protocols have been proposed, in which disulfides, sulfinic acid and their salts, sulfonyl chlorides, sulfonylhydrazine, or Nthiophtalimides are used as source of electrophilic sulfur.10,15-16 Thiosulfonates (RSO2SR’) are another class of emerging17 reagents, which were also studied for C-S bond formation18-20 and for indole sulfenylation.21 However, despite the large pool of sulfenylation agents listed above, the difficult activation of the chalcogen centre essentially limits these reagents to the formation of C-S(aryl) bonds. On the other hand, the transfer of alkylsulfenyl groups requires harsher activating conditions and is so far still limited<br>

scholarly journals Efficient C3-alkylsulfenylation of indoles under mild conditions using Lewis acid-activated 8-quinolinethiosulfonates.

2020 ◽  
Author(s):  
erwan galardon
Keyword(s):  
Lewis Acid ◽  
The Other ◽  
Sulfinic Acid ◽  
Metal Free ◽  
Noble Metal Catalysts ◽  
Mild Conditions ◽  
Large Pool ◽  
Metal Catalyzed ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

The importance of sulfur-containing compounds in various fields, ranging from material science1-2 to medicinal chemistry, 3 has called for the development of synthetic strategies to form carbon-sulfur (C-S) bonds. Thus, numerous approaches based on the nucleophilicity of thiols have been designed over the years, which mostly use air-sensitive noble metal catalysts.4- 9 At the opposite, the use of electrophilic sulfur reagents is also a powerful, more eco-friendly approach, in particular for the sulfenylation of C-H bonds into C-S bonds.10-11 In this context, the sulfenylation of indoles (Equation 1) has become a benchmark reaction to develop and test new sulfenyl transfer reagents, because indoles are good nucleophiles and their occurrence in many natural products or biological active compounds makes them attractive synthetic targets.12-14 For instance, metal-catalyzed or metal-free protocols have been proposed, in which disulfides, sulfinic acid and their salts, sulfonyl chlorides, sulfonylhydrazine, or Nthiophtalimides are used as source of electrophilic sulfur.10,15-16 Thiosulfonates (RSO2SR’) are another class of emerging17 reagents, which were also studied for C-S bond formation18-20 and for indole sulfenylation.21 However, despite the large pool of sulfenylation agents listed above, the difficult activation of the chalcogen centre essentially limits these reagents to the formation of C-S(aryl) bonds. On the other hand, the transfer of alkylsulfenyl groups requires harsher activating conditions and is so far still limited<br>

scholarly journals Efficient C3-alkylsulfenylation of indoles under mild conditions using Lewis acid-activated 8-quinolinethiosulfonates.

2020 ◽  
Author(s):  
erwan galardon
Keyword(s):  
Lewis Acid ◽  
The Other ◽  
Sulfinic Acid ◽  
Metal Free ◽  
Noble Metal Catalysts ◽  
Mild Conditions ◽  
Large Pool ◽  
Metal Catalyzed ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

The importance of sulfur-containing compounds in various fields, ranging from material science1-2 to medicinal chemistry, 3 has called for the development of synthetic strategies to form carbon-sulfur (C-S) bonds. Thus, numerous approaches based on the nucleophilicity of thiols have been designed over the years, which mostly use air-sensitive noble metal catalysts.4- 9 At the opposite, the use of electrophilic sulfur reagents is also a powerful, more eco-friendly approach, in particular for the sulfenylation of C-H bonds into C-S bonds.10-11 In this context, the sulfenylation of indoles (Equation 1) has become a benchmark reaction to develop and test new sulfenyl transfer reagents, because indoles are good nucleophiles and their occurrence in many natural products or biological active compounds makes them attractive synthetic targets.12-14 For instance, metal-catalyzed or metal-free protocols have been proposed, in which disulfides, sulfinic acid and their salts, sulfonyl chlorides, sulfonylhydrazine, or Nthiophtalimides are used as source of electrophilic sulfur.10,15-16 Thiosulfonates (RSO2SR’) are another class of emerging17 reagents, which were also studied for C-S bond formation18-20 and for indole sulfenylation.21 However, despite the large pool of sulfenylation agents listed above, the difficult activation of the chalcogen centre essentially limits these reagents to the formation of C-S(aryl) bonds. On the other hand, the transfer of alkylsulfenyl groups requires harsher activating conditions and is so far still limited<br>

Regioselective C3-H Trifluoromethylation of 2H-Indazole Under Transition-Metal-Free Photoredox Catalysis

2019 ◽  
Author(s):  
Arumugavel Murugan ◽  
Venkata Nagarjuna Babu ◽  
Nagaraj Sabarinathan ◽  
Sharada Duddu. S
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Practical Approach ◽  
Hypervalent Iodine ◽  
Radical Mechanism ◽  
Photoredox Catalysis ◽  
Metal Free

Here we report a visible-light-promoted metal-free regioselective C3-H trifluoromehtylation reaction that proceeds via radical mechanism and which supported by control experiments. The combination of photoredox catalysis and hypervalent iodine reagent provides a practical approach for the present trifluoromethylation reaction and synthesis of a library of trifluoromethylated indazoles.

Highly chemoselective deoxygenation of N-heterocyclic N-oxides under transition metal-free conditions

2021 ◽  
Vol 19 (16) ◽  
pp. 3735-3742
Author(s):  
Se Hyun Kim ◽  
Ju Hyeon An ◽  
Jun Hee Lee
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Eosin Y ◽  
Metal Free ◽  
Simple Protocol

Here, we provide an operationally simple protocol for the highly chemoselective deoxygenation of various functionalized N-heterocyclic N-oxides under visible light-mediated photoredox conditions with Na2-eosin Y as an organophotocatalyst.

scholarly journals Recent Advances in Transition-Metal-Free (4+3)-Annulations

Synthesis ◽  
2021 ◽  
Author(s):  
Heather Lam ◽  
Mark Lautens ◽  
Xavier Abel-Snape ◽  
Martin F. Köllen
Keyword(s):  
Transition Metal ◽  
Boronic Acid ◽  
Lewis Acids ◽  
Acid Catalysis ◽  
Heterocyclic Carbenes ◽  
Bronsted Acids ◽  
Metal Free ◽  
Previous Review ◽  
Dual Activation ◽  
Metal Catalyzed

Abstract(4+3)-Annulations are incredibly versatile reactions which combine a 4-atom synthon and a 3-atom synthon to form both 7-membered carbocycles as well as heterocycles. We have previously reviewed transition-metal-catalyzed (4+3)-annulations. In this review, we will cover examples involving bases, NHCs, phosphines, Lewis and Brønsted acids as well as some rare examples of boronic acid catalysis and photocatalysis. In analogy to our previous review, we exclude annulations involving cyclic dienes like furan, pyrrole, cyclohexadiene or cyclopentadiene, as Chiu, Harmata, Fernándes and others have recently published reviews encompassing such substrates. We will however discuss the recent additions (2010–2020) to the literature on (4+3)-annulations involving other types of 4-atom-synthons.1 Introduction2 Bases3 Annulations Using N-Heterocyclic Carbenes3.1 N-Heterocyclic Carbenes (NHCs)3.2 N-Heterocyclic Carbenes and Base Dual-Activation4 Phosphines5 Acids5.1 Lewis Acids5.2 Brønsted Acids6 Boronic Acid Catalysis and Photocatalysis7 Conclusion

Transition metal-catalyzed arylation of unstrained C−C single bonds

2021 ◽  
Author(s):  
Long Yang ◽  
Wuxin Zhou ◽  
Qiang Li ◽  
Xiangge Zhou
Keyword(s):  
Organic Chemistry ◽  
Transition Metal ◽  
Bond Activation ◽  
Important Research ◽  
Carbon Bond ◽  
Research Areas ◽  
Carbon Carbon Bond ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Single Bonds

Carbon−carbon bond activation is one of the most challenging and important research areas in organic chemistry. Selective C−C bond activation of unstrained substrates is difficult to achieve owing to its...

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