The Renaissance of Alkali Metabisulfites as SO2 Surrogates

Abstract

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.

Sulfinates from Amines: A Radical Approach to Alkyl Sulfonyl Derivatives via Donor–Acceptor Activation of Pyridinium Salts

“…Sulfinate salts are versatile intermediates used in the synthesis of a variety of sulfonyl-derived functional groups that are frequently found in agrochemicals and pharmaceuticals . Bench-stable SO 2 surrogates, such as the amine–SO 2 Lewis adduct DABSO (DABCO·(SO 2 ) 2 ), or inorganic metal bisulfites, such as Na 2 S 2 O 5 , used in combination with metal catalysts, organometallic reagents, , or reactive intermediates, have made a tremendous impact on the synthesis of aryl sulfinates. However, applications to the preparation of alkyl sulfinates are more limited.…”

Multicomponent Reactions Based on SO2 Surrogates: Recent Advances

“…Patel's review has summarized recent advancements in sulfonylation reactions using K 2 S 2 O 5 or Na 2 S 2 O 5 as the SO 2 source [6b] . To avoid duplication, we only select some reactions to illustrate the characteristics of sulfite salts in MCRs.…”

Mn(OAc)3-Promoted Sulfonation–ipso-Cyclization Cascade via the SO3– Radical: The Synthesis of Spirocyclic Sulfonates

“…Despite a few reported examples of sulfonated azaspiro­[4,5]-trienones and azaspiro­[4,5]-decanes in recent years, they are limited to sulfone preparation and are typically unable to undergo further modification. − In 2021, Wang’s group published the pioneering study on the sulfonation of electron-deficient alkenes using SO 3 – radicals for the synthesis of oxindole-based sulfonates . Recently, we have shown that the combination of Mn­(OAc) 3 − and K 2 S 2 O 5 − can effectively promote the oxidative sulfonation of functionalized alkenes via SO 3 – radicals as the key intermediate (Scheme A) . This success was attributed to the development of a suitable oxidative environment that matched well with the reactive SO 3 – radical.…”