Copper® sulfinates

Suzuki, H., and Abe, H., A new straightforward synthesis of alkynyl sulfones via the sonochemical couphng between alkynyl halides and copper sulfinates. Tetrahedron Lett., 37, 3717, 1996. 

Alkynyl sulfones. A straightforward preparation of these sulfones consists of the nochemical induction of coupling of 1 -iodoalkynes with copper sulfinates (tosylates, etc.) - THF. 

The coupling of acetylenic iodides with copper sulfinates leads to the formation of uncommon acetylenic sulfones (Fig. 26). Sonication promotes this reaction, which can be made even easier by using a mixture of the sulfinic acid and commercial copper "carbonate" (a hydrated mixture of copper carbonate and hydroxide).i54 Successful results were also recorded in an extension using copper thiosulfonates and copper dimethyl phosphite. 

Additions of sulfinic acids to polyenes ( hydrosulfonylation ), however, proceed with very strong acids80 or under catalysis of Pd complexes81 (equation 17). With copper(II) arenesulfinates, azulene has been oxidatively sulfonylated in the 1- and 2-positions of the five-membered ring82 (equation 18). The sulfonylmercuration has also been applied with success to conjugated dienes83 (equation 19). 

Whereas acyclic sulfoxides form complexes with various metal salts, thiirane oxides react with copper(II) chloride or bromide163 in benzene at room temperature to give the thiolsulfonate 146a. In alcoholic solution below 0 °C the major products are sulfinates (149). Similar results are obtained in the reaction of thiirane oxides with ethanesulfinyl chloride163 as summarized in equation 60. 

Aryl sulfones have been prepared from sulfinic acid salts, aryl iodides and Cul. Unactivated thiocyanation has been accomplished with charcoal supported copper(I) thiocyanate." ... 

Diazonium salts can be converted to sulfonyl chlorides by treatment with sulfur dioxide in the presence of cupric chloride. The use of FeS04 and copper metal instead of CUCI2 gives sulfinic acids (ArS02H). See also 13-18. 

Sulfur dioxide (see above) as well as S02, SO , and SOj have been used as building blocks in three-component sulfone syntheses. It has long been known that aromatic sulfinic acids are easily available from diazonium salts and sulfur dioxide under copper catalysis . Mechanistically, aryl radicals as reactive intermediates add to sulfur dioxide generating arenesulfonyl radicals, which either take up an electron (or hydrogen) yielding a sulfinic acid or add to an olefinic double bond yielding final y -halogenated alkyl aryl sulfones (equation 78). 

In a similar reaction, chloro(tnfluoromethyl)sulfine is formed by the dechlon nation of 1,1 dichloro-2,2,2-tnfluoroethanesulfinyl chlonde with copper at 200 °C in the gas phase [66] (equation 34)... 

This nucleophilic replacement of halogen atoms proceeds under mild conditions due to the neighboring azo group and the presence of copper ions. The o-sulfonic acid group is also susceptible to the copper-mediated nucleophilic substitution, and other nucleophiles, such as alkoxy, alkylamino, cyano, and sulfinic acid can also replace the halogen atom in the position ortho to the azo group in the presence of copper ions. 

Antongst other confounds which function as accelerators with diazonium salts are thiourea dioxide (formamldine sulfinic acid), and p-tolylhydrazine. whilst copper is the most efficient of the metal ions, catalytic qviantities giving a large Increase in R, some other transition metals have a marked effect. These include titanic sulfate and vanadyl sulfate. 

Calcium-binding Proteins Copper Enzymes in Denitrification Copper Proteins with Type 1 Sites Copper Proteins with Type 2 Sites Iron Heme Proteins Electron Transport Iron-Sulfin Proteins Metal-mediated Protein Modification Metallochaperones Metal Ion Homeostasis Molybdenum MPT-containing Enzymes Nickel Enzymes Cofactors, Nitrogenase Catalysis Assembly Zinc Enzymes. 

Aryl sulfones have been prepared from sulfinic acid salts, aryl iodides and Formation of thiocyanates from unactivated aryl halides has been accomplished with charcoal supported copper(l) thiocyanate. " The copper catalyzed reaction of Na02SMe and aryl iodides give the aryl methyl sulfone. " A similar synthesis of diaryl sulfones has been reported using a palladium catalyst. " ... 

FIGURE 2.40 The major pathway for taurine biosynthesis in the liver- First, cy teine is converted to cysteine sulfinic acid in an oxygen-requiring reaction catalyzed by an iron metalloeozyme- The second step, catalyzed by a vitamin B -requiring enzyme, is a decarboxylation reaction. The final step appears to be catalyzed by a copper metaLloenzyme and to require oxygen. Apparently, about one-fourth of the cysteine in the liver eventually is converted to taurine. 

Although N sulfinyl imines can be prepared by several other methods (oxidation of sulfenimines [12] and iminolysis of sulfinates [13]), they are most conveniently synthesized by condensing aldehydes with tert butanesulfinamide in the presence of copper(II) sulfate or magnesium sulfate/pyridinium p toluenesulfonate as a Lewis add catalyst and water scavenger (Scheme 1.4) [14]. When ketones, more sterically hindered aldehydes or even electronically deactivated aldehydes are used, titanium tetraethoxide is the preferred Lewis add and water scavenger. These methods are convenient to synthesize both alkyl and aryl substituted imines. 

Stereoselective conversion of propargylic compounds to haloallenes normally proceeds with high anti stereoselectivity. On the other hand, syn selectivity is observed for the copper(I) bromide hydrobromide induced conversion of propargylic alcohol into the corresponding 1-bromoallene with low enantiomeric excess (6% ee). The sulfinate ester, however, again gave anti stereoselectivity with moderate enantiomeric excess150. 

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