Cuprous triflate

The copper complex 1s available from Strem Chemicals, Inc., under the name cuprous triflate (benzene complex). The checkers recommend handling the material In a dry box because of Its high moisture and air sensitivity. 

Acyclic dienes as 1,6-heptadienes can be converted to bicyclic compounds, e.g. bicyclo[3.2.0]heptanes, in the presence of cuprous triflate (4.36) 439). 

The treatment of various sulfides with Phi = NTs in the presence of cuprous triflate leads to the corresponding N-tosylsulfimides (N-tosylsulfilimines) 21 [30]. The presence of the chiral bis(oxazoline) ligand 22 in the reaction medium results in coordination of the copper(III)-nitrene intermediate, L Cu(III) = NTs, and enables the enantioselective production of 21 (Scheme 12). Similar copper-catalyzed reactions of allylic sulfides with Phi = NTs lead to formal insertion of the NTs group into the carbon-sulfur bond of the substrates, and proceed via a [2,3]-rearrangement with allylic inversion, to give sulfonamides 23 [30]. 

Modestly enantioselective tosylimidations of a series of 2-substituted -1,3-dithianes 24 with Phi = NTs, cuprous triflate, and the chiral bis(oxazoline) ligand... 

Enantioselective conversions of aryl benzyl selenides to N-tosylselenimides 28 with [(tosylimino)iodo]benzene, cuprous triflate, and the chiral bis(oxazo-line) 22 have recently been demonstrated (Scheme 16) [37,38]. Because benzyl phenyl selenide undergoes uncatalyzed imidation with Phi = NTs in acetonitrile (46 % yield) or dichloromethane (trace yield), toluene was selected as the solvent for the asymmetric imidation reactions. Furthermore, in order to avoid racem-ization of 28 by moisture, molecular sieves were added to the reaction medium. 

Asymmetric aziridination was also successfully performed using benzylidene derivatives of 1,2-diaminocyclohexane in presence of cuprous triflate [45],... 

The presence of catalytic amounts of cuprous triflate or silver(I) sulfonates exerts a remarkable influence on the activation energy and regiochemistry of alkynyl(phenyl)-iodonium tosylate and mesylate decompositions5,6. Such reactions proceed in acetonitrile at room temperature and afford moderate yields of alkynyl tosylates and mesylates (equations 82 and 83)5,6. It is noteworthy, however, that the treatment of alkynyliodonium triflates (R = n-Bu, r-Bu) with cuprous triflate in acetonitrile does not afford alkynyl triflates6. Silver(I) catalysis has similarly been applied to the conversion of bis(alkynyliodo-nium) tosylates to bisalkynyl tosylates (equation 84)43. As might be expected, mono-tosylate esters are also produced in these reactions. 

Several mechanisms for the catalytic action of Cu(I) and Ag(I) have been considered6. Among these, the metal-assisted addition-elimination sequence shown in equation 85 and illustrated with cuprous triflate was deemed most consistent with various control studies. A mechanism not discussed but equally plausible is the metal-assisted MC sequence depicted in equation 86. The greater separation of iodonium-sulfonate ion pairs in acetonitrile versus benzene should provide the tosylate (or mesylate) ions with sufficient mobility to add to the /7-carbon atom of the alkynyliodonium ion. 

Ring contraction of 156 under cuprous triflate catalysis occurs stereoselec-tively to give either (5)- or (R)-pyrrolidones 157 in 95% yield (95AG104). 

Ullmann reaction. When o-iodonitrobenzene (1) is treated at room temperature with cuprous triflate in acetone solution containing 5% aqueous ammonia. 

This elimination reaction has been applied to the adducts (2) obtained by reaction of lithio dithiophenoxymethane (1) with aldehydes or ketones. Treatment of (2) with cuprous triflate and a base gives the homologous a-thio-phenoxy ketone (3) with preferential migration either of hydrogen or of the more highly substituted alkyl group. 

Cuprous triflate can also be used for coupling of vinyl halides (c/. Use of copper powder, 4, 102-103). In this case acetone saturated with ammonia gas is superior to aqueous ammonia. 

Biid cycloheptanone. The intermediate (8) is an a-epoxythioether and can also he prepared by reaction of cycloheptanone with the ylide (11). If the reaction of (7) with cuprous triflate is condueted at 62°, 1-thiophenoxycycloheptanecar-hoxuldehyde (9) is obtained as the major product. 

A neat synthesis of a- and /S-panasinsene (255) has been described which incorporates an intramolecular variant of the cuprous triflate-catalysed photocycloaddition of the allylic alcohol (253) to afford (254).Oxidation of (254), followed by treatment with methyl-lithium and dehydration yielded a mixture... 

Ring-expansion Reactions. The thioacetal (41), which had been prepared from cyclohexanone and the lithium derivative of dithiophenoxymethane in 74% yield, rearranged on treatment with cuprous triflate in the presence of a 3° amine to give 2-... 

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