Silanes silyl sulfides

CHfiSSi ro A") Methyl silyl sulfide (Methylthio)silane 00 deg")... 

In addition to the numerous examples of the McMurry couplings described above, the following examples illustrate the power of the transformation in the synthesis of a broad range of natural products and non-natural molecules. Of particular note in the following examples is the impressive functional group tolerance of the McMurry conditions. In general, alcohols, tosyl alcohols, alkyl ethers, silyl ethers, alkyl silanes, vinyl silanes, amines, sulfides, and alkenes are inert to McMurry conditions. Acteals, halides, alkynes, nitriles, and carboxylic acids are semi-compatible. 

The addition of trisubstituted silanes to carbonyl sulfide has been applied to the synthesis of the corresponding silanethiol derivatives (Reaction 5.40) [78]. In Scheme 5.12 the mechanism is depicted, starting from the silyl radical attack to the sulfur atom of 0=C=S and ejection of carbon monoxide. The resulting silanethiyl radical abstracts hydrogen from the starting silane, to give the silanethiol and to generate fresh silyl radical (see Section 3.4). 

Triphenylsilyl- 300 and 2- and 3 - trimethylsily benzo[6]thio-phene 391,392 have been prepared, and their rates of cleavage by acids and bases measured. The reaction between 2-benzo[6 thienyltrichloro-silane and jp-bromophenyl methyl sulfide in the presence of sodium gives 2-[tri( )-methylthiophenyl)silyl]benzo[6]thiophene.3fl ... 

Moreover, the formation of enoxy-silanes via silylation of ketones127 by means of N-methyl-N-TMS-acetamide (1 72) in presence of sodium trimethylsilanolate (173) was reported in 1969 and since then, the use of silylating reagents in presence of a catalyst has found wide appreciation and growing utilization as shown in recent papers128-132 (Scheme 27). Diacetyl (181) can be converted by trifluoromethylsul-fonic acid-TMS-ester (182) into 2,3-bis(trimethylsiloxy)-l, 3-butadiene (7treatment with ethyl TMS acetate (7 5)/tetrakis(n-butyl)amine fluoride l-trimethylsiloxy-2-methyl-styrene (i<56)130. Cyclohexanone reacts with the combination dimethyl-TMS-amine (18 7)/p-toluenesulfonic acid to 1-trimethylsiloxy-l-cyclohexene (iSS)131. Similarly, acetylacetone plus phenyl-triethylsilyl-sulfide (189) afford 2-triethylsiloxy-2-pentene-4-one (790)132. ... 

Cyclohexanones can be dehydrogenated to enones by treatment of the corresponding enol silanes with DDQ in the presence of a catalytic amount of the bis-silyl derivative of acetamide. However, the yields fall off drastically when the reaction is applied to cyclopentanones and cyclo-heptanones. Another new method for dehydrogenation of carbonyl compounds consists of conversion to their pyridine-2-sulfIde derivatives, followed by oxidation (MCPBA), and by mild heat. ... 

Silanes normally reduce aldehydes or ketones under catalytic conditions to the silyl ethers. However, with certain catalysts such as nickel sulfide,Co2(CO)8, or (Ph3P)3RhCl, carbonyl compounds react with silanes to yield an equilibrium mixture of enol silyl ethers (Scheme 17). In a similar vein, the silyl-hydroformylation reaction of cycloalkenes with CO and silanes may be a practical way to prepare enol silyl ethers. An example is the preparation of compound (49). Catalytic 1,4-hydrosilation of a, -un-saturated ketones or aldehydes gives the corresponding enol silyl ethers. The reaction is similar to the reductive silylation referred to previously, but the reaction conditions are neutral and milder. The formation of the enol silyl ether (50) is outlined below. ... 

Silicon Transfer Reagent Bis(trimethylsilyl) sulfide can transform alcohols, acids, and amines into their silylated counterparts. Enol silanes are also formed under the influence of this... 

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