Ketones copper triflate

Lithiated [bis(phenylsulfanyl)methyl]trimethylsilane reacts readily with a,) -unsaturated ketones to give the enolates 1. Ring closure accompanied by elimination of lithium ben-zenethiolate occurs upon warming in the presence of equimolar amounts of copper triflate to give the 1-phenylsulfanyl-1-trimethylsilylcyclopropanes 2. 

Salomon and his coworkers have over the years studied the influence of copper(I) triflate on the cyclization of non-conjugated dienes. In the present example the diene (170) is converted readily on irradiation in the presence of the catalyst and affords the alcohol (171). This is oxidised to the corresponding ketone. The intramolecular cyclization of the diene (172), using a copper triflate catalyst, affords the straight (2-1-2) adduct (173). This cyclization was used as an approach to the synthesis of RobustadiaJ B. However, it was shown that the proposed structure of the natural product was wrong and that the robustadials should have the camphahe moiety in their structure as shown in (174). ... 

In recent years some work has been done to link oleochemicals with petrochemicals via oligomerization. One possibility is the Dids-Alder reaction of linoleic acid esters with dienophiles, for instance with quinones or ,/Tun saturated aldehydes and ketones [80]. Using scandium or copper triflates as catalysts the reaction can be carried out at very mild temperature conditions (25-40°C) with good yields (< 94%). For the first time in oleochemistry it was possible to carry out Diels-Alder cycloadditions with low catalyst concentrations instead of stoichiometric amounts of Lewis acids. The most successful way to recycle the catalyst was the successive extraction of the triflates with water. After removing the water and drying in vacuum the catalyst was used three times without any loss of yield. 

Direct a-Phenylations of Cyclic Ketones. Copper enolates obtained by reaction of the corresponding lithiate with stoichiometric amounts of anhydrous copper cyanide react with diphenyliodonium triflate to afford Q ,Q -diphenylated or a-phenylated ketones in moderate yields. Five-membered cyclic ketones gave only Q, o -diphenylated compounds, whereas larger cyclic ketones afford only cK-phenylated products (eq 1). It is noteworthy that copper enolates afford the best yields of phenylated compounds. 

As anticipated from the complexation experiments, reaction of 4.42 with cyclopentadiene in the presence of copper(II)nitrate or ytterbium triflate was extremely slow and comparable to the rate of the reaction in the absence of Lewis-acid catalyst. Apparently, Lewis-acid catalysis of Diels-Alder reactions of p-amino ketone dienophiles is not practicable. 

Buynak et al. reported the synthesis of representative 7-vinylidenecephalosporine derivatives bearing an axial allene chirality (Scheme 4.5) [9]. A chiral allene 24 was prepared stereoselectively utilizing the reaction of an organocopper reagent with propargyl triflate 23, obtained by a diastereoselective ethynylation of the ketone 22 with ethynylmagnesium bromide. Terminally unsubstituted allene 26 was synthesized via bromination of the triflate 23 followed by reduction of the bromide 25 with a zinc-copper couple. 

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... 

It has been reported that diphenyliodonium triflate reacts with the lithium enolates of some cyclic ketones in the presence of copper cyanide to yield the corresponding a-phenylated or a-diphenylated ketones.58 There has been a detailed analysis of the products of thermal decomposition of diphenyliodonium tetrafluoroborate and hexafluorophosphate salts.59... 

Arylations with aryliodonium salts can be effectively catalyzed by transition metals. The arylation of the lithium enolates of cyclic ketones with di-phenyliodonium triflate in the presence of stoichiometric quantities of copper cyanide affords the corresponding a-phenylated ketones in moderate yields [73]. 

Taking into account the competitive hydrolysis of the silyl enol ether, this reaction is remarkable. The method was shown to be general and was extended to a variety of aldehydes and several a,j9-unsaturated carbonyl compounds giving uniformly 1,4-addition with aldehydes and a mixture of 1,4- and 1,2-adducts in the case of ketones [187]. Later, this aqueous version of the Mukaiya-ma reaction was shown to give near quantitative yields in the presence of a water-tolerant Lewis acid such as ytterbium triflate [188]. Keeping with the same concept,copper(II) triflate [189],indium(III) trichloride [190],tris(pentafluoro-phenyl)boron [191] and scandium(III) triflate in the presence of a surfactant [192] have proved to be active catalysts. 

Aminopyridines can be used in other ways copper-catalysed interaction with diazo-ketones and three-component reactions involving an isonitrile and an aldehyde also give imidazo[l,2-a]pyridines such condensations can be promoted using an ionic liquid" or scandium triflate with microwave heating." In the former route, 2-substituted products result and from the latter, 3-aminoimidazo[l,2-a]pyridines are formed. 

The first examples reported were the copper(ll) complexes of 28 and 61, both with NCCH3 as the sixth ligand, and crystallized as the triflate salt (82). Both were available in the 9-ketone and the hydrated forms. These complexes have identical chromophores and only differ in the substituent at N7 [see Rg. 11 (o and... 

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