Sulfur trioxide dimethyl sulfoxide activator

In an example of the use of this activation method testosterone, with a IT -hydroxy group, was oxidized to A -androstene-3,17-dione very rapidly in high yield, in contrast to the use DMSO-acetic anhydride. During a reaction, when other oxidizing agents were found to be ineffective, sulfur trioxide/dimethyl sulfoxide led to smooth oxidation of the df-diol (16 equation 8) to an o-quinone in 49% yield and the ci.r-diol (17) to (18 equation 9) in 98% yield. - The use of dimethyl sulfoxide-acetic anhydride for this oxidation gave large amounts of the diacetate as the by-product. 

The above discussion has concentrated upon the reagents used, but it is equally of value to comment on the substrate, particularly in reactions for which other oxidation methods have been reported to fail. A good example is the oxidation of the iron-carbonyl complex (31) to the ketone (32 equation 14). The use of dimethyl sulfoxide activated with sulfur trioxide-pyridine complex gave a 70% yield of the product, in contrast to the use of the Pfitzner-Moffatt procedure (dimethyl sulfoxide-DCC) or the chromium... 

There are several methods reported in the literature for transforming vicinal diols into ct-diketones while avoiding the risk of C-C bond cleavage.26 Examples include the standard Swem conditions (dimethyl sulfoxide and oxalyl chloride followed by triethylamine), or the use of DMSO activated by acetic anhydride, pyridine-sulfur trioxide complex, or dicyclohexylcarbodiimide (Mq/J-att oxidation). Diones are also obtained by treatment with benzalacetone as a hydride acceptor in the presence of catalytic amounts of tris(triphenylphosphine)ruthenium dichlonde [(PPh RuCFl.27 Recent developments include the use of w-iodoxyben/.oic acid28 or the oxoammonium salt of 4-acctamidoletramethylpipcridine-1-oxyl and y -toluencNulfonic acid.29... 

One of the best activators fw dimethyl sulfoxide is the complex of sulfur trioxide/pyiidine, which in the presence of triethylamine rapidly oxidizes primary and secondary alcrdmls to aldehydes and ketones in very good yields at ambient temperature. This reagent also allows the very useM crmversion of allylic alcohols to the corresponding a, unsaturated carbonyl compounds. A further advantage of this procedure over many of the others is the ease of woiit-up, especially over the dimethyl sulfoxide-dicy-clohexylcarbodiimide method. 

The sulfur trioxide- dine activated dimethyl sulfoxide oxidation was also a key step in an excellent synthesis of die Prelog- jerassi lactonic acid, being highly recommended as the best method to avoid epimeiization of the C-2 center in the aldehyde (33). ... 

Other hazardous reactions may occur with carbon (e.g., soot, graphite, activated charcoal), dimethyl sulfoxide, ethylene oxide, chlorine, bromine vapor, hydrogen bromide, potassium iodide + magnesium bromide, chloride or iodide, maleic anhydride, mercury, copper(II) oxide, mercury(II) oxide, tin(IV) oxide, molybdenum(III) oxide, bismuth trioxide, phosphoms trichloride, sulfur dioxide, chromium trioxide. 

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