Sulphinate esters cyclic

Enantiomeric distinction can also be achieved using chiral solvents without shift reagents. The determination of enantiomeric purity and the assignment of absolute configuration of cyclic and acyclic sulphinate esters has recently been achieved (573) using chiral l-aryl-2,2,2-trifluoroethanols as solvents. Enhanced enantiomeric distinction has been demonstrated using a combination of both a chiral solvent and an achiral LSR. (514)... 

It has been proposed54 that oxidative cyclizations such as these occur via the formation of the cyclic sulphinate esters (sultines) with subsequent oxidation to the corresponding sultone as shown in equation 34 for the formation of 16. 

Sultines (cyclic sulphinate esters) can be readily oxidized to sultones by hydrogen peroxide or potassium peroxysulphate. The first example of such a synthesis was reported by King and De Mayo and their associates69 who prepared l,2-oxathiole-2,2-dioxide (22)... 

Four-membered Rings.—Open-chain sulphinate esters are readily prepared but their cyclic analogues are less easily come by. [2 + 2]Cycloadditions involving SO2 are limited to a few specialized examples, and it has been suggested that it is this mode of reaction that leads to the initially formed adduct (274) between SO2 and ketenimines. These compounds are unstable and rearrange to thiazetidine 5-oxides (275) in 90% yield. A versatile approach has been... 

Sulphines are formed by the oxidation of thiones with peroxy-acids, but they then react further, albeit much more slowly, to give the ketone, sulphur, and sulphur dioxide. This latter reaction is kinetically similar to many other oxidations with peroxy-acids, and the results are consistent with electrophilic attack of the peroxy-acid on the C=S double bond to give a cyclic sulphinate ester (4), which rapidly decomposes to give the ketone and sulphur monoxide. In contrast, oxidation of thiobenzanilide 5-oxide with m-chloroperoxybenzoic acid gives products derived from the sulphene PhC(NHPh)=SOa. Further examples of the reaction between diarylsulphines and aryldiazomethanes to give epi-sulphoxides have been reported. ... 

Sultines, Sultones, and Related Systems.—A general synthesis of sultines (144) (cyclic sulphinate esters), based on the reaction of t-butyl hydroxyal-kyl sulphoxides (145) with SO2CI2 or N-chlorosuccinimide, has been developed. The method was shown to be suitable for the preparation of sultines varying in ring size from 5 to 8 and having a variety of alkyl or aryl substitution patterns. 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

In recent years the importance of entropy contributions to the increased rates of reaction of five-membered cyclic esters has been recognised. Thus the high reactivity of the oxaphospholan ring has been shown to arise from a combination of both enthalpy and entropy strain153. On the other hand, entropy strain is the main cause of kinetic acceleration in the alkaline hydrolysis of cyclic sulphite and sulphinate esters154,155. 

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