Alcohols sulfide conversion

The Mitsunobu reaction, discovered by Mitsunobu in the late 1960s, has become one of the most widely used reactions in organic chemistry. The reaction has become the standard method for the inversion of secondary alcohols, the conversion of alcohols into amines and sulfides, and many other applications. New uses for this versatile reaction continue to be developed. The Mitsunobu reaction, due to its mild reaction conditions, has found wide application in total synthesis, and heterocyclic and medicinal chemistry. Since the Mitsunobu reaction has been extensively reviewed during the last thirty years, this chapter will focus primarily on applications of the Mitsunobu reaction during the last fifteen years. This review will cover recent examples for the various uses of the Mitsunobu reaction and introduce several new applications of the reaction. Recently developed phosphine and azadicarboxylate reagents will be covered as well. 

A larger scale application of an alcohol into sulfide conversion was... 

Usually, organoboranes are sensitive to oxygen. Simple trialkylboranes are spontaneously flammable in contact with air. Nevertheless, under carefully controlled conditions the reaction of organoboranes with oxygen can be used for the preparation of alcohols or alkyl hydroperoxides (228,229). Aldehydes are produced by oxidation of primary alkylboranes with pyridinium chi orochrom ate (188). Chromic acid at pH < 3 transforms secondary alkyl and cycloalkylboranes into ketones pyridinium chi orochrom ate can also be used (230,231). A convenient procedure for the direct conversion of terminal alkenes into carboxyUc acids employs hydroboration with dibromoborane—dimethyl sulfide and oxidation of the intermediate alkyldibromoborane with chromium trioxide in 90% aqueous acetic acid (232,233). 

Conversion of Allyl alcohols into their Corresponding Thiols or Diallyl Sulfides... 

Conversion of haloperidol to reduced haloperidol (a secondary alcohol) Glutathine dependent reduction of disulfiram to deithyldithiocarbamate Thioredoxin dependent of sulindac to sulindac sulfide DT diaphorase reduction of menadione to hydroquinone Conversion of pentabromoethane to tetra bromoethane (releasing free bromide ion)... 

Chemical deoxygenation of sulfoxides to sulfides was carried out by refluxing in aqueous-alcoholic solutions with stannous chloride (yields 62-93%) [186 Procedure 36, p. 214), with titanium trichloride (yields 68-91%) [203], by treatment at room temperature with molybdenum trichloride (prepared by reduction of molybdenyl chloride M0OCI3 with zinc dust in tetrahydrofuran) (yields 78-91%) [216], by heating with vanadium dichloride in aqueous tetrahydrofuran at 100° (yields 74-88%) [216], and by refluxing in aqueous methanol with chromium dichloride (yield 24%) [190], A very impressive method is the conversion of dialkyl and diaryl sulfoxides to sulfides by treatment in acetone solutions for a few minutes with 2.4 equivalents of sodium iodide and 1.2-2.6 equivalents of trifluoroacetic anhydride (isolated yields 90-98%) [655]. 

Esters of 4-oxoacids, such as ethyl levulinate, can also be cyclized in the cold by treatment with hydrogen sulfide under acid conditions. An early report (39JCS1116) described the conversion of diethyl 2-acetylsuccinate (168) to ethyl 2-methyl-5-ethoxythiophene-3-carboxylate (169), by treatment with hydrogen sulfide in alcoholic HC1 at 0 °C. The reaction was reviewed in 1977 <77PS(3)377) a large number of 4-oxoesters (170) were subjected to the hydrogen sulfide treatment, and the products were carefully isolated and characterized. 

Hydrogen sulfide ion (HS ) Use of hydrogen sulfide as a nucleophile permits the conversion of alkyl halides to compounds of the type RSH. These compounds are the sulfur analogs of alcohols and are known as thiols. 

Sulfides can be prepared from alcohols. A convenient conversion under mild conditions and in high yields has been published [20], The work-up is particularly simple. 

Dess-Martin A5-iodane 44 is an extremely useful reagent for the conversion of primary and secondary alcohols to aldehydes and ketones at 25 °C [70]. It does not oxidize aldehydes to carboxylic acids under these conditions. It selectively oxidizes alcohols in the presence of furans, sulfides, and vinyl ethers. The oxidation mechanism involves a facile ligand exchange with alcohols, followed by reductive /1-elimination. 

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