Acylations copper chloride

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... 

Photochemical decomposition of diazo(trimethylsilyl)methane (1) in the presence of alkenes has not been thoroughly investigated (see Houben-Weyl Vol. E19b, p 1415). The available experimental data [trimethylsilylcyclopropane (17% yield) and la,2a,3/J-2,3-dimethyl-l-trimethylsilylcyclopropane (23% yield)] indicate that cyclopropanation occurs only in low yield with ethene and ( )-but-2-ene.24 In both cases the formal carbene dimer is the main product. In reactions with other alkenes, such as 2,3-dimethylbut-2-ene, tetrafluoroethene or hexafluoro-propene, no cyclopropanes could be detected.24 The transition-metal-catalyzed decomposition of diazo(trimethylsilyl)methane (1) has been applied to the synthesis of many different silicon-substituted cyclopropanes (see Table 3 and Houben-Weyl Vol.E19b, p 1415).3-20a b-11 Copper chloride has been most commonly used for carbene transfer to ethyl-substituted alkenes, cycloalkenes, styrene, and related arylalkenes.3,203,15,21 25 For the cyclopropanation of acyl-substituted alkenes, palladium(II) chloride is the catalyst of choice, while palladium(II) acetate was less efficient, and copper chloride, copper(II) sulfate and rhodium(II) acetate dimer were totally unproductive.21 The cyclopropanation of ( )-but-2-ene represents a unique... 

Acylations. Alkenylzirconocene chlorides that are generated from hydrozirconation of alkynes readily undergo copper-catalyzed acylations. Thus, enones containing tin and selenium substituents are available from alkynylstannanes and alkynylselenides, respectively. Alkenyl alkynyl ketones are obtained when the reaction is carried out under carbon monoxide with alkynyliodonium salts. ... 

Organozirconocene Chlorides. Acyl zirconocene chlorides function as efficient donors of acyl anions and can react with allylic or propargylic halides (X=Cl, Br, I, OTs) under Cul catalysis. In these reactions, acyl copper species (RCOCu), generated by the transfer of acyl group fromZr to Cu, were speculated to be the reactive species. These Cul-catalyzed reactions of acyl zirconocene chloride are cort5)lementary to the palladium-catalyzed reactions and enable the formation of -y-unsaturated ketones, which suffer ready isomerization under the palladium-catalyzed conditions (eq 23). On the other hand, carbonylative cross-coupling of F-o -selanylvinylzirconiums with alkynyUodonium tosylates can be performed in THF in the presence of 3 mol% of Cul and atmospheric pressure of carbon monoxide in a palladium-free system. 

For example, the reaction of nitronates (123) with a zinc copper pair in ethanol followed by treatment of the intermediate with aqueous ammonium chloride a to give an equilibrium mixture of ketoximes (124) and their cyclic esters 125. Heating of this mixture b affords pyocoles (126). Successive treatment of nitronates (123) with boron trifluoride etherate and water c affords 1,4-diketones (127). Catalytic hydrogenation of acyl nitronates (123) over platinum dioxide d or 5% rhodium on aluminum oxide e gives a-hydroxypyrrolidines (128) or pyrrolidines 129, respectively. Finally, smooth dehydration of a-hydroxypyrrolidines (128) into pyrrolines (130f) can be performed. 

A typical procedure calls for reaction of the hemiacetal donor with dicydohexyl carbodiimide and copper(I) chloride (0.1 equiv) at 80 °C, followed by an addition of the acceptor and continued heating. As an early demonstration of this protocol, oc-riboside 86 was prepared in moderate yield but with exclusive stereoselectivity [141]. Further measures were required for the glycosylation of monosaccharide acceptors, such as addition of p-toluenesulfonic add (0.1 equiv) to promote the formation of disaccharide 87 [144]. The method was more suitably applied to the synthesis of O-acyl glycopeptides, as evidenced by the formation of 88 in 60% yield [143,144]. Various peptides with non-nudeophilic side chains were found to be amenable to this stereoselective reaction. The [3-selectivity was suggested to arise from a preponderance of the a-isourea intermediate 85 in the activation step. 

The syntheses of 1 utilized the Ullmann ether synthesis.13 Reaction of 2 mol of 1-bromonaphthalene with 4,4-(hexafluoroisopropylidiene)diphenol afforded the desired product 1. The reaction was carried out in DM Ac at 160°C in the presence of potassium carbonate as the base and copper (I) iodine as the reaction catalyst to yield 1, as depicted in Scheme 1. The reaction proceeded slowly but in good yield with easy isolation of the desired compound. Acylation of 1 with 4-fluorobenzoyl chloride to prepare 2 was carried out under modified Friedel-Crafts reaction conditions14 using dimethyl-sulfone as catalyst moderator. Both 1 and 2 were easily recrystallized to yield high-purity monomers suitable for polymerizations. 

The regioselectivity is maintained with mono- and even disubstituted propargylic chlorides (Table 9.33) [56], The copper complex affords allenylcarbinols (A) and the nickel complex favors homopropargylic alcohols (B). In the latter case, the syn adducts are predominant, suggestive of an acylic transition state. 

Furthermore, the preparation and reactions of 2-methoxythiophene were studied by Sice (70). This compound was obtained by a copper catalysed Williamson synthesis. It was also found that iodothiophene reacted readily with sodium alkoxides, whereas bromothiophene reacted slowly and chlorothiophene did not react at all. Sodium iodide accelerated the reaction of bromothiophene. The ortho, para orienting alkoxy group on carbon atom 2 increased the directive influence of the sulphur atom to the 5 position but competed with it to induce some attack on the 3 position by electrophilic reagents (nitration, acylation). The acylation of 2-methoxythiophene with stannic chloride at low temperatures furnished a mixture of two isomers. The 5-methoxy-2-acetothienone was obtained in higher yield and was identified by its ultraviolet absorption spectrum. 

The reaction between zinc-copper reagents and acid chlorides is very general and provides a useful synthesis of ketones [7, 34, 41, 42], This acylation has also been used to prepare various indoles substituted in position 2 (Scheme 2.42) [88],... 

Acylation reactions can also be greatly improved in this way, with t-alkyl- or sec-alkyl-manganese reagents reacting with acid chlorides in excellent yields [123]. The related addition-elimination to 3-ethoxy-2-cyclohexenone is also improved, resulting after acidic aqueous workup in 3-methyl-2-cyclohexenone [125]. The perilla-ketone 126 was prepared in an improved yield using copper(I) catalysis (Scheme 2.58) [129]. 

Reduction of cuprous chloride with sodium borohydride gives copper hydride which is a highly selective agent for the preparation of aldehydes from acyl chlorides [775]. 

In order to modulate the reactivity of intermediate 331, it was transformed into its copper derivative by treatment with copper(I) bromide or iodide in THF at —78 °C, and then was allowed to react with a,/3-unsaturated carbonyl compounds (to give compounds 343 resulting from a conjugated addition), acyl chlorides (to give ketones 344) and copper(II) chloride (to dimerize giving compounds 345) (Scheme 100)"° ". ... 

Also in the case of intennediate 374, a lithium-copper transmetallation with a copper(I) halide (bromide or chloride) allowed one to carry out the conjugate addition [to electrophilic olefins R CH = CH2Z (Z = COR, CO2R) giving compounds 381 in 31-76% yield], the acylation (with acyl chlorides yielding ketones 382 in 35-65% yield) and dimerization [using copper(II) chloride as the additive, to give compound 383 in 59% yield] processes ... 

Electrophiles, which lead to high yields, are methyl iodide, trialkyltin- and trialkylsUyl chlorides, diphenylphosphinyl chloride, acid chlorides, aldehydes and carbon dioxide. Remarkably, though highly acidic ketones are formed on acylation, no deprotonation or racemization by excess of carbanionic species occurs. Other alkyl halides than methyl iodide react very sluggishly with low yields. Benzylic and aUylic halides lead to partial racemization, presumably due to single-electron transfer (SET) in the alkylation step. As very recently found by Papillon and Taylor, racemization of 42 can be suppressed by copper-zinc-lithium exchange before alkylation to 43 via the Knochel cuprates (equation 7) °. 

Upon acylation of the copper complex with benzoyl chloride the corresponding 5-benzoylthio-1,2,3,4-thiatriazole is formed. The reaction product is (apparently) incorrectly assigned by the authors to 4-benzoyl-1,2,3,4-thiatriazole-5-thione based upon comparison with the product obtained from direct acylation of thiatriazol-5-thiol and citation of the older incorrect structure assignments. The thiothiatriazolato-copper(I) complexes are formulated as Cu-N(4) complexes. However, this assignment is based upon an IR band at 1200 cm attributed to a thiocarbonyl group, again upon comparison with the older literature. Further characterization therefore seems necessary. 

Acyl cyanides can be prepared by reaction of acid chlorides with cyanotrimethyl-silane at 60-70°1 or with copper cyanide.2. ... 

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