Sulfinate anion

Alkylation of fluonnated carboxylate [4J] and sulfinate anions [42] occurs readily (equations 37 and 38)... 

Other possible ambident nucleophiles include cyanii anion (CN ), methyl sulfinate anion (CH3SO2 ), ar acetone enolate (CH3COCH2 ). Identify the most electro rich atom(s) in each anion (based on charges alone), ar indicate the major product that should result from an S, reaction with methyl bromide at this atom(s). 

Nucleophilic substitutions of halogen by the addition-elimination pathway in electron-deficient six-membered hetarenes by sulfinate anions under formation of sulfones have been described earlier120. The corresponding electron-poor arenes behave similarly121 (equation 30). A special type of this reaction represents the inverse Smiles rearrangement in equation 31122. 

In the first mechanism (equation 74) the nucleophile function attacks the aromatic ring in an ipso-type displacement involving a Meisenheimer complex intermediate243,244, and leads to the rearranged product after expulsion of sulfinate anion (X-). This mechanism should be favoured by the presence of an electron-withdrawing substituent in conjugation with the anion. The second mechanism (equation 75) involves a direct displacement of sulfinate anion (X ) by Y-, without involvement of the aromatic n electrons. 

In reducing media, a synthetically useful variation of the Smiles rearrangement, which leads to the formation of fused ring systems, has been observed (equation 77)251. In this reaction, rearrangement is followed by displacement of the sulfinate anion by a nucleophilic o -substituent. 

Thus at acidic pH the formation of ions increases the conductivity, while at basic pH the higher specific conductivity anion OH- is replaced by the less-conducting (CH3)2S02-anion. The yield of the sulfinic anion can be measured from the decrease in conductivity at basic pH and the increase at acidic pH (equation 26-27). 

The reduction rate of R (low reduction potential)1 is faster than any chemical reaction such as trapping by enolate ion. The difference from the electrochemical results is that, in the latter, the secondary reduction of the sulfinate anion does not occur. 

The cleavage of alkyl aryl sulfones by sodium amalgam and alcohols65 probably proceeds also through the intermediacy of a radical anion, followed by splitting to the arylsulfinate anion and an alkyl radical. Both the sulfinate anion and the disproportionation products of the radical have been observed. 

TABLE 2. Sulfones from S-acylations of sulfinate anions RSOj... 

Sulfone 411 gave the ring-opened product upon treatment with a catalytic amount of LDA in THF-HMPA, whereas treatment of 412 with f-BuOK in DMF resulted in ringopening and elimination of a sulfinate anion . 

In the mechanism proposed, arylketene (which is thought to be an intermediate in this reaction), is attacked by the sulfinate anion acting as a nucleophile. 

Brown and Darwent (1979) recently demonstrated that the hydrophobic effect is also important in the micellar activation of peroxide nucleophiles. Engberts and coworkers reported that proton abstraction by sulfinate anions is facilitated (103-104-fold) in the CTAB micelle (Jagt and Engberts, 1977 van Langkruis and Engberts, 1979). 

C-H insertion of an alkylidene carbene intermediate, which was generated via the Michael addition of a sulfinate anion to the acetylenic p-carbon. In MeOH,... 

The tandem MCI reaction of / -ketoethynyl- and /J-amidoethynyl-A3-iodanes with sulfinate anion was demonstrated by Stang and co-workers [Eq. (107)] [188]. They further showed that the bis(alkynyliodane) 117 undergoes the double MCI reaction yielding the bis(cyclopentene) products [189]. 

However, an ElcB-type process was reported as a novel mechanism for hydrolysis of a /3-sultam. In the case of the N-a -methoxycarbon y I /3-sultam, deprotonation of the acidic exocyclic hydrogen leads to the formation of a carbanion, which then undergoes a rate-limiting conversion to a ring-opened species with expulsion of a sulfinate anion. Then, hydrolysis of the imine species produces benzoyl formate as the principal product detected (Scheme 14) <2002CC772>. 

Alkynyltriphenylbismuthonium salts react with sodium />-toluenesulfinate in dual reaction modes depending on the solvents employed (Equation (133)).217 When the reaction is conducted in DMF, 1-tosylcyclopentene is formed through 1,5-C-H insertion of an alkylidene carbene intermediate, generated via Michael addition of the sulfinate anion to the /3-carbon. When the reaction is carried out in MeOH, l,2-bis(sulfonyl)alkenes are produced via sequential Michael addition and nucleophilic substitution of the sulfinate anion. 

The nucleophile is a stable enolate and the leaving group is a sulfinate anion. An intermediate must be formed in which the negative charge is delocalized on to the carbonyl group on the ring, just as you saw in the benzene ring examples in Chapter 23. Attack occurs at the 2-position because the... 

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