Copper!I triflate

The submitters state that the copper(I) triflate is quite air stable In solution In the presence of the allyllc alcohol. 

Silver(I) Inflate and copper(I) triflate can be applied as catalysts A representative example is the preparation of alkynyl tosylates by the catalytic decomposition of alkynyl lodonium salts in the presence of these salts [727] (equation 67)... 

Corey et al. [19] simultaneously reported similar studies using a2,2 -bis(oxazolyl)-6,6 -dimethyl-l,l -biphenyl as copper(I)triflate chelate. This hgand afforded a stable monomeric chiral Cu(I) complex providing a highly... 

The presence of Cu(I) salts promotes intermolecular photocycloaddition of simple alkenes. Copper(I) triflate is especially effective.182 It is believed that the photoreactive species is a 2 1 alkene Cu(I) complex in which the two alkene molecules are brought together prior to photoexcitation.183... 

Copper(I) triflate can facilitate these intramolecular additions, as is the case for inter-molecular reactions. 

Copper(II) triflate is quite inefficient in promoting cyclopropanation of allyl alcohol, and the use of f-butyl diazoacetate [164/(165+166) = 97/3%] brought no improvement over ethyl diazoacetate (67/6 %)162). If, however, copper(I) triflate was the catalyst, cyclopropanation with ethyl diazoacetate increased to 30% at the expense of O/H insertion (55%). As has already been discussed in Sect. 2.2.1, competitive coordination-type and carbenoid mechanisms may be involved in cyclopropanation with copper catalysts, and the ability of Cu(I) to coordinate efficiently with olefins may enhance this reaction in the intramolecular competition with O/H insertion. 

Lehn has also reported the hydrogen-bonding templated assembly of receptors based on bipyridine copper and palladium complexes [102]. A mixture of substituted bipyridines (76, 77) (see Scheme 39) with copper(I) triflate generates a mixture of tetrahedral complexes and uncoordinated ligands. 

Direct, controlled preparation of copper(I) complexes was achieved by Evans [7] from bisoxazolines and copper(I)triflate, which avoids the use of other methods for reduction or accidental reduction by the substrate, which may not always be efficient. When isobutene is the substrate one obtains only two enantiomers and no other products for styrene we obtain a cis and a trans product each occurring as a pair of enantiomers. We will illustrate this with styrene and the results of Pfaltz s semicorrin-copper. 

Because of the high nucleophilicity and reactivity of diazoalkanes, catalytic decomposition occurs readily, not only with a wide range of transition metal complexes but also with Brpnsted or Lewis acids. Well-established catalysts for diazodecomposition include zinc halides [638,639], palladium(II) acetate [640-642], rhodium(II) carboxylates [626,643] and copper(I) triflate [636]. Copper(II)... 

Direct coupling of imidazole with aryl iodides in the presence of copper(I) triflate results in 1-aryl-imidazoles, which can be alkylated in a second step [Eq. (5)]. This route represents a variation of the Gridnev method. ... 

The most widely exploited photochemical cycloadditions involve irradiation of dienes in which the two double bonds are fairly close and result in formation of polycyclic cage compounds. Some examples are given in Scheme 6.7. Copper(I) triflate facilitates these intramolecular additions, as was the case for intermolecular reactions. 

Intramolecular cyclopropanations are also well documented in the literature. It has been shown by Koskinen and co-workers that the cyclopropanation of diazomalonate 57, illustrated in Figure 9.18, using benzyl bis(oxazoline) 40 and copper(I) triflate afforded lactone 58 in 73% yield and 32% ee. Nishiyama and coworkers showed that cyclopropanations of diazoacetates 59a-c proceeded in yields ranging from 79-93% and 24-86% ee (Table 9.6, Fig. 9.18, p. 544). ... 

The power of chiral C2-symmetric bis(oxazolines) in cyclopropanation reactions has also been exhibited in total synthesis. One example is Corey and co-workers synthesis of sirenin 63 using bis(oxazoline) ligand 8 (Fig. 9.19). They showed that the intramolecular cyclopropanation of diazo derivative 61 proceeded in 77% yield and with 90% ee. Shibasaki and co-workers constructed prostratin 67 through the intermediate cyclopropane 66, also shown in Figure 9.19. Using bis(oxazoline) ligand 64 and copper(I) triflate-derived catalyst, compound 66 was prepared in 70% yield and 92% ee from diazo derivative 65. ... 

Uemura and co-workers discovered that prochiral sulfides react with [N-(p-toluenesulfonyl)imino]phenyliodinane 207 in the presence of bis(oxazoline) ligands to form the corresponding chiral sulfimides. ° For example, ( )-cinnamyl phenyl sulfide 220 reacted with 207 in the presence of copper(I) triflate and ent-6 to form the chiral sulfimide 221 in 80% yield (58% ee) as shown in Figure 9.63. 

In certain cases, when the palladium or nickel catalyzed coupling is not efficient or fails completely, an alternate solution is provided by the use of copper based catalyst systems. The 5-iodouracil derivative shown in 7.77. was unreactive towards imidazole using either the Buchwald-Hartwig conditions or the copper(I) triflate promoted the carbon-nitrogen bond formation reported by Buchwald98 These latter conditions, however, were effective in coupling the iodouracil with a series of other amines (7.77.), The optimal catalyst system consisted of copper(I) triflate, phenantroline and dibenzylideneacetone (dba).99... 

Finally, a recently reported copper catalyzed carbon-nitrogen bond forming process utilises reagents with polarity opposite to the common disconnection protocols. An electrophilic nitrogen, in most cases an (9-acyl hydroxylamine derivative, was successfully coupled with diarylzinc reagents in the presence of copper triflate or copper chloride. Di(2 -pyridyl)zinc and TV-benzoyloxy-morpholine were reacted at ambient temperature in the presence of 1% copper(I) triflate to give 2-morpholinopyridine in 71% yield (7.81.), Under these mild conditions the reaction was over in less than one hour.103... 

An intramolecular photocyclization catalyzed by copper(I) triflate provided a key step in a total synthesis of the ginseng sesquiterpenes a- and /J-panasinsene, (8) and (9). The unsaturated allylic alcohol (6) is cyclized by irradiation at 254 tun in the presence of CuOTf to a mixture of saturated alcohols, which is oxidized to the ketone 7. The ketone is inert to methylenetriphenylphosphorane, but can be converted into a 2 5 mixture of 8 and 9 by addition of mcthyllithium followed by dehydration.2... 

Another phenoxide activating approach published by Buchwald et al. [18] is based on the reaction of cesium phenoxides with aryl bromides or iodides in the presence of catalytic amounts of copper(I) triflate and ethyl acetate in refluxing toluene (Scheme 3b). In certain cases equimolar amounts of 1-naphthoic acid have been added in order to increase the reactivity of the phenoxide. The authors assume the formation of a cuprate-like intermediate of the structure [(ArO)2Cu] Cs+ as the reactive species. In addition, diaryl ether formation between phenols and aryl halides has been achieved using a phosphazene base forming naked phenoxide in the presence of copper bromide in refluxing toluene or 1,4-dioxane [19]. 

Isolation of the air-sensitive silacyclopropene was avoided by development of a two-step, one-flask procedure, which transformed alkynes into the desired azasilacyclopentadienes (Scheme 7.29)." For terminal alkynes, silver phosphate was employed for di-terf-butylsilylene transfer and copper(I) triflate was used to promote nitrile insertion. These conditions successfully transformed phenylacetylene into azasilacyclopentadiene 106b. For internal alkynes, copper(I) triflate catalyzed both silylene transfer to 3-hexyne as well as nitrile insertion to produce enamine 106k. 

While investigating trisubstituted allylic ethers, Woerpel and coworkers observed insertion of silylene into the allylic C-O bond (Scheme 7.56).136 The product formation was dependent on the identity of the catalyst. Silver trifluor-oacetate promoted the formation of allylic disilane 201, whereas copper(I) triflate... 

Copper-catalyzed [2 + 2] photocycloadditions are related to the latter reactions. These transformations have been extensively studied, frequently in the context of application to organic synthesis [21], When irradiated in the presence of copper(I) triflate, norbomene 12 was effidently transformed into its dimer 13 (Scheme 5.3, reaction 4) [22]. Although complexes such as III are involved in the reaction mechanism [22, 23], it is unclear whether MLCT (metal to ligand charge transfer) or LMCT (ligand to metal charge transfer) excitation induces the transformation. 

Interestingly, when using copper(I)triflate, the cyclopentadiene dimer 14 reacts in an intermolecular way, leading to the cydobutane 15 (reaction 5) [22], When the same substrate is transformed in the presence of the triplet sensitizer acetone, an intramolecular [2 + 2] cycloaddition takes place and the cage hydrocarbon compound 16 is formed. Obviously, the formation of a copper complex intermediate involving both alkene double bonds of the substrate is unfavorable in this case. 

Sensitized intramolecular reaction of two 1,3-dienes (86) (Sch. 17) yields predominantly the [2+2] adduct 87, with small amounts of [4+4] adduct 89 and little, if any, [4+2] product 88 [58,59], consistent with Hammond results for intermolecular reactions of acyclic dienes (Sch. 4). Benzophenone-sensitized reaction yields a mixture of two isomers of 87. Heating this mixture to 200 °C converts both isomers of 87 to cyclo-octadiene 89 [58]. Unsensitized photoreaction of 86 in the presence of copper(I) triflate gives a significant amount of [4+2] adduct 88. Extended irradiation time converts much of 87 and 89 into 88, as well as producing secondary products [59]. Copper triflate-mediated photocycloaddition of a related tethered diene-monoalkene, gave only the [2+2] adduct [59]. 

Following the publication of our method, similar procedures were reported by two other groups. One involves the use of bromamine-T as a nitrogen source instead of CT for the aziridination of olefins [14] the other is the copper(I) triflate-catalyzed aziridination and allylic amination with CT trihydrate [7d] (Schemes 8 and 9). 

A different approach that even obviates the use of a preformed silyllithium reagent takes advantage of the cleavage of the Si-Si bond of a disilane by a copper salt. Hosomi and co-workers185 have reported on the reaction of various enones or enals 250 with hexamethyldisilane or l,l,2,2-tetramethyl-l,2-diphenyldisilane, catalyzed by copper(i) triflate-benzene complex (Scheme 61). The transformation requires heating to 80-100 °C in DMF or DMI and the presence of tri-/z-butylphosphine in order to stabilize the copper catalyst under these harsh conditions. The addition products 251 were obtained with high yield after acidic work-up. The application of the method to alkylidene malonates as the Michael acceptor was recently disclosed.1... 

Alkynylation of aziridines can be effected through the copper-catalyzed ring opening with acetylides. For example, lithium phenylacetylide engages in smooth nucleophilic attack of A-tosyl-7-azabicyclo[4.1.0]heptane 160 in the presence of copper(i) triflate to provide the cyclohexyl alkyne 161 in excellent yield (Scheme 42) <2004SL1691>. 

Oxidations. A widely used method for allylic oxidation is the Kharash-Sosnovsky reaction using a peroxide and a copper(I) salt system. Enantioselective allylic oxidations of cycloalkenes such as cyclopentene, cyclohexene and cycloheptene with tert-butyl peibenzoate were investigated with a variety of catalysts derived from bis(oxazoline) ligands and copper(I) triflate complexes (eq 18). The ligand-copper(I) complexes from the /-Bu-... 

Thioacetals readily eliminate to vinylsnlfides at room temperature in the presence copper(I) triflate [46]. Acyclic (75) and cyclic (77) substrates react equally well (Sch. 20). The a-ketothioacetal 79 furnished furan 80, presumably via a carbocation mechanism, and the diene 82 resulted from sequential elimination of two sulfides from 81. 

Copper(I) triflate was used as a co-catalyst in a palladium-catalyzed carbonylation reaction (Sch. 27). The copper Lewis acid was required for the transformation of homoallylic alcohol 118 to lactone 119. It was suggested that the CuOTf removes chloride from the organopalladium intermediate to effect olefin complexation and subsequent migratory insertion [60]. Copper(I) and copper(II) chlorides activate ruthenium alkylidene complexes for olefin metathesis by facilitating decomplexation of phosphines from the transition metal [61]. 

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