Methyl sulfinate anion

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). 

The first step is conjugate addition of the highly stabilized anion. The intermediate enolate then closes the three-membered ring by favourable nucleophilic attack on the allylic carbon. The leaving group is the sulfinate anion and the stereochemistry comes from the most favourable arrangement in the transition state for this ring closure. The product is the methyl ester of the important chrysan-themic acid found in the natural pyrethrum insecticides. 

The room temperature treatment of a series of 1-alkenyl 2-(trime-thylsilyl)ethyl sulfones leads to an intermediate o , 8-unsaturated sulfinate anion which can be methylated at sulfur to produce methyl sulfones in 54-83% (eq 12). If alkyl hydrogens are attached at a position y to the sulfonyl groups, undesirable double bond migration may occur. Although not specifically demonstrated, alkylation with other electrophiles may be possible, as shown for arenesulfinate anions. ... 

An example of fluoride induced conversion is of a hetaryl 2-(trimethylsilyl)ethyl sulfone to the sulfinic acid via protonation of the sulfinate anion. The treatment of a collection of arenesulfinate anions, obtained from the corresponding 2-(trimethylsilyl)ethyl sulfones, with H2NOSO3H gave aryl sulfonamides in 50-85% yield (eq 13). In this case and elsewhere, the aryl 2-(trimethylsilyl)ethyl sulfones are prepared through the deprotonation of aryl methyl sulfones and quenching of the a-sulfonyl carbanion with trimethylsilylmethyl iodide, or the less expensive trimethylsilylmethyl chloride. Such a protocol is complementary to the oxidation of 2-(trimethylsilyl)ethyl thioethers. 

Our attempts to prepare useful materials by chemical modification of poly(vinylidene bromide) (Ref. 50) were not very successful, although, in reactions with the anions of methyl mercaptan or 2-mercaptoethanol under phase transfer conditions, degrees of substitution as high as 55% were obtained, while a reaction with the less nucleophilic sodium methyl sulfinate gave only 46% conversion. The reactions were accompanied by extensive elimination and the final modified polymers were always highly colored. 

Schneider and Simon82 prepared / -ketosulfoxides 47a and 47b by sulfinylation of the dianions of the methyl acetoacetates 48a and 48b with sulfinate ester 19 followed by decarboxylation of the intermediate products (Scheme 2). Apparently this avoids racemiz-ation experienced by others in the direct synthesis of these compounds9. /J-Ketosulfoxides are also available from the reaction of the anion derived from methyl p-tolyl sulfoxide with esters (see Section II.E). They can also be obtained, in some cases, through the hydrolysis of a-sulfinylhydrazones whose synthesis is described below. Mention has already been made of the synthesis of 2-p-tolylsulfinylcycloalkanones such as 32. 

Methanol-0-4 methyl nitrite, and dimethyl disulfide have been examined as potential chemical probes for distinguishing between alkoxides and enolates in the gas phase. Methanol-0-(/ proved to be unsuitable and methyl nitrite reacts too slowly in contrast, the reactive ambident behaviour of dimethyl disulfide results in elimination across the C—S bond on reaction with alkoxides ( hard bases ) and attack at sulfin by enolates ( soft bases ). This probe has been applied to investigation of the anionic oxy-Cope rearrangement. The dianionic oxy-Cope rearrangement is a key step in a squarate ester cascade involving stereoinduced introduction of two alkenyllithium reagents cis to each other. 

The Truce-Smiles rearrangement is general for diaryl sulfones containing an o-methyl group and involves benzylic deprotonation to the anion which subsequently rearranges to the sulfinate. If the sulfinate contains a suitably placed leaving group, further reactions may occur for example, the chlorophenyl sulfone (114) forms the sulfinate (115), but this... 

A versatile non-Friedel-Crafts approach to naphthols is provided by condensation of the toluic acid sulfoxide with substituted acrylates or methyl vinyl ketone. Sequential conjugate addition and acylation of the first formed anion leads to the tetralone. Pyrolysis leads to aromatiza-tlon by loss of sulfinic acid. 

More recently, another example involving the intermediacy of phosphonylated sul fines has been reported. Treatment of diethyl 3-methyl-l,2-butadienylphosphonate with LDA at low temperature followed by reaction with MejSiCl leads to the desired diethyl l-(trimethylsilyl)-3-methyl-l,2-butadienylphosphonate. The addition of alkyllithiums to the a,P-doublc bond of this very unstable compound gives the a-phosphonylated carbanions, which are allowed to react with an excess of SO2. The resulting sulfines are stirred overnight, and only low yields of diethyl 2-thienylphospho-nates (12-25%) are obtained, contaminated with protonated anion (Scheme 2.23). The separation of these two compounds proved to be problematic. The major disadvantage of the method is the incomplete reaction of the anion with S02. ... 

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