Trimethylsilyl ethanethiol

Solubility soluble in MeOH, CH2CI2, THF, and most organic solvents. 

Form Supplied in liquid from major research chemical suppliers at a cost of ca. US 60/g (7.4 mmol) of 97% pure material. 

Handling, Storage, and Precaution the thiol possesses a strong unpleasant aroma that combines the characteristic olfactory features of thiol and low molecular weight silane. As a thiol, the reagent is incompatihle with oxygen, base, and common oxidants. Distillation should he carried out with care since 

A list cf General Abbreviations appears on the front Endpapers 

Thiol Substitution Reactions. Vital to the usefulness of 2-(trimethylsilyl)ethanethiol is that it behaves as a typical thiol. Base mediated reactions that proceed as expected include alkylation and nucleophilic ring openings. Moreover, addition-eliminations on unsaturated systems, Michael additions, and c -additions to triple bonds (eq 2) are all routine. To access 2-(trimethylsilyl)ethyl thioethers, a useful procedure is hydrolysis of 2-(trimethylsilyl)ethyl thiolacetate and alkylation of the thiolate in a single pot.  

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Synthesis of mixed disulfides involving a methylthio unit may utilize DMTSF. Thiols and thiolates react rapidly with the reagent to yield mixed disulfides. Unfortunately, disproportionation occurs, resulting in a mixture of products. Subsequent investigations suggest that the addition of a stericaUy hindered base (eq 3), or the use of a 2-(trimethylsilyl)ethanethiol derived component (eq 4), permit high yields of unsymmetrical disulfides. 

Trimethylsilyl)ethanethiol will also participate in aromatic and heteroaromatic displacements of halogen atoms. A recent example shows that 2-(trimethylsilyl)ethanethiol is an alternative for the commonly employed potassium ethyl xanthate as a latent thiol in nitrogen displacement chemistry of aromatic di-azonium ions (eq 3). The low 3neld occurs in the substitution step, and is believed to be due to the sensitive doubly brominated substrate. ... 

Reactions at acid centers to create 5 -2-(trimethylsilyl) ethanethiolesters are also common. Carboxylic 5-thiolesters are formed in high yield by the DCC/DMAP mediated coupling of 2-(trimethylsilyl)ethanethiol and carboxylic acids or by thiol substitution on a carboxylic acid chloride. 5 -2-(Tiimethylsilyl) ethyl p-toluenethiolsulfonate is formed by treating 2-(trimethyl-silyl)ethanethiol with tosyl bromide (eq 4). The product is a useful electrophile for carbon nucleophiles, allowing the introduction of the 2-(trimethylsilyl)ethylthio unit by an alternative mechanism. Independent of the thiol, aryl and alkyl 2-trimethylsilylethyl thioethers may be prepared by the radical addition of the appropriate arene- or aikanethiol to vinyl trimethyl-silane in a reaction comparable to that of eq l7 ... 

Introduction of a Divalent Snifnr Equivalent. One function where 2-(trimethylsilyl)ethanethiol exhibits its value is as a mononucleophilic sulfide equivalent where the sulfur acts as a nucleophile only once. Hence the reagent displays the nucleophilic strength of a typical aikanethiol to afford a stable product. Liberation of the 2-(trimethylsilyl)ethyl group with alkali metal fluorides and 18-crown-6 or tetralkylammonium fluorides converts the sulfide moiety to a thiolate (eq 5). Innocuous trimethylsilyl fluoride and ethylene are believed to be the by-products of fluoride treatment. 

In order for the 2-(trimethylsilyl)ethylthio unit to lose its protecting group upon treatment with the fluoride, the sulfur must be attached to an unsaturated carbon. Hence the fluoride mediated sulfur deprotection is feasible for 2-(trimethyl-silyl)ethylthio substituted (het)arenes, alkenes, alkynes, and acid derivatives such as carboxylic and selenothiophosphinic acid salts. In thiolate form, the substrates have value for the formation of self-assembled monolayers or as metal complexing agents. Simple addition of acid to the thiolate to give a stable thiol characterizes 2-(trimethylsilyl)ethanethiol as a simple M" (HS) equivalent that is only capable of a single substitution reaction. ... 

The double addition of two 2-(trimethylsilyl)ethanethiols and hence placement of two 2-(trimethylsilyl)ethylthio groups close to one another in a molecule offers a protocol for use of 2-(trimethylsilyl)ethanethiol as a M+ S-S M+ equivalent. This chemistry was developed while pursuing the formation of the... 

Of all the options, the use of 2-(trimethylsilyl)ethanethiol is possibly the most expensive. Nevertheless its versatility and enduring popularity as a M+ S-S M+ equivalent is demonstrated by the preparation of a 1,2-benzodithiolanone for studies modeling the bioactivity of leinamycin (eq 8). Moreover, the use of fluoride as a deprotecting agent is unique and often innocuous to other functionalities. Divorced of 1,2-dithiin or -dithiolanone chemistry, an isolated example of direct conversion of an alkyl 2-(trimethylsilyl)ethyl sulflde to the dialkyl disulflde using BrCN (70%) has been reported. ... 

Direct alkylation has been achieved in special circumstances. Thus 2-(trimethylsilyl)ethyl sulfides, obtainable from alkylation of 2-(trimethylsilyl)ethanethiol or by radical addition of thiols to vinyl trimethylsilane, react with a-glycosyl bromide with the assistance of Ag(I) activation to offer a general synthesis of 8-thioglycosides. Yields generally vary (34-99%), and the fi a ratio can be quite high (eq 10). ... 

Alkenyl 2-(trimethylsilyl)ethyl sulfones, which are readily prepared from 2-(trimethylsilyl)ethanethiol by way of Wittig chemistry and oxidation, provide a source of 1-alkenesulfinate salts. ... 

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