Cyclo copper

Estr-5(10)-ene-3a,17 -diol (10 g, 36.2 mmoles) is added over a period of 1 hr to a refluxing mixture consisting of 60 g (0.92 moles) of zinc-copper couple, 350 ml of dry ether and 180 g (54 ml, 0.67 moles) of methylene iodide. After the addition is complete, half of the solvent is removed by distillation and 200 ml dry ether is added. The reaction mixture is then transferred to a sealed stainless steel tube and maintained for 3 hr at 92° before being cooled in an ice bath and poured into 500 ml of saturated aqueous sodium bicarbonate solution. The resultant mixture is extracted with ether and the extracts are dried over anhydrous sodium sulfate and concentrated to yield a solid residue which gives 8.4 g (80%) 5,19-cyclo-5a,10a-androstane-3a,17) -diol mp 161-163° [aJo 40° (CHCI3), on crystallization from acetone. 

Dicyclohexylammonium nitrite s (DCHN) has a solubility of 3-9g in 100 g of aqueous solution at 25°C, giving a solution pH of about 6-8. Its vapour pressure at 25°C appears to be about 1-3 x 10 N/m but the value for commercial materials depends markedly on purity. It may attack lead, magnesium, copper and their alloys and may discolour some dyes and plastics. Cyclohexylammonium cyclohexyl carbamate (the reaction product of cyclohexylamine and carbon dioxide, usually described as cyclo-hexylamine carbonate or CHC)" is much more volatile than DCHN (vapour pressure 53 N/m at 25°C), and much more soluble in water (55 g in 100cm of solution at 25°C, giving a pH of 10-2). It may attack magnesium, copper, and their alloys, discolour plastics, and attack nitrocellulose and cork. It is said to protect cast iron better than DCHN, and to protect rather better in the presence of moderate concentrations of aggressive salts. 

The reversal of the stereoselectivity is attributed to the ability of chlorotrimethylsilane to trap the initially formed cuprate-enone complex, thereby suppressing equilibration of the diastereomeric complexes. The copper-catalyzed 1,4-addition of Grignard reagents to 5-substituted 2-cyclo-hexenone also proceeded with very high trans diastereoselectivity22. 

Carboxylic acids, a-bromination of 55, 31 CARBOXYLIC ACID CHLORIDES, ketones from, 55, 122 CARBYLAMINE REACTION, 55, 96 Ceric ammonium nitrate [Ammonium hexa mtrocerate(IV)[, 55, 43 Chlorine, 55, 33, 35, 63 CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Cinnamomtnle, a-phenyl- [2-Propeneni-tnle 2,3-diphenyl-], 55, 92 Copper(l) iodide, 55, 105, 123, 124 Copper thiophenoxide [Benzenethiol, copper(I) salt], 55, 123 CYCLIZATION, free radical, 55, 57 CYCLOBUTADIENE, 55, 43 Cyclobutadieneiron tricarbonyl [Iron, tn-carbonyl(r)4-l,3-cyclo-butadiene)-], 55,43... 

Numerous examples have been pubhshed dealing with the heterogeneization of copper complexes, as immobihzed catalysts for the asymmetric cyclo-propanation of alkenes. Some of them have already been mentioned in the text for a direct comparison with their homogeneous coimterparts. Other reusable catalytic systems have been developed and will be described as follows. 

The above-described structures are the main representatives of the family of nitrogen ligands, which cover a wide spectrum of activity and efficiency for catalytic C - C bond formations. To a lesser extent, amines or imines, associated with copper salts, and metalloporphyrins led to good catalysts for cyclo-propanation. Interestingly, sulfinylimine ligands, with the chirality provided solely by the sulfoxide moieties, have been also used as copper-chelates for the asymmetric Diels-Alder reaction. Amide derivatives (or pyridylamides) also proved their efficiency for the Tsuji-Trost reaction. 

Diazomalonic esters, in their behavior towards enol ethers, fit neither into the general reactivity pattern of 2-diazo-l,3-dicarbonyl compounds nor into that of alkyl diazoacetates. With the enol ethers in Scheme 17, no dihydrofurans are obtained as was the case with 2-diazo-l,3-dicarbonyl compounds. Rather, copper-induced cyclo-propanation yielding 70 occurs with ethoxymethylene cyclohexane u4). However,... 

Copper-catalyzed cyclopropanation of benzene and its derivatives by a diazoacetic ester yields a norcaradiene 230 which undergoes spontaneous ring opening to cyclo-heptariene 231. At the temperatures needed for successful cyclopropanation, sigma-tropic H-shifts leading to conjugated isomers of cycloheptatriene carboxylates cannot be avoided. The situation is complicated by the formation of regioisomers upon cyclopropanation of substituted benzenes, and separation of the cycloheptatriene isomers may became tedious if not impossible. 

In 1966, Nozaki et al. reported that the decomposition of o-diazo-esters by a copper chiral Schiff base complex in the presence of olefins gave optically active cyclopropanes (Scheme 58).220 221 Following this seminal discovery, Aratani et al. commenced an extensive study of the chiral salicylaldimine ligand and developed highly enantioselective and industrially useful cyclopropanation.222-224 Since then, various complexes have been prepared and applied to asymmetric cyclo-propanation. In this section, however, only selected examples of cyclopropanations using diazo compounds are discussed. For a more detailed discussion of asymmetric cyclopropanation and related reactions, see reviews and books.17-21,225... 

Various approaches to epoxide also show promise for the preparation of chiral aziridines. Identification of the Cu(I) complex as the most effective catalyst for this process has raised the possibility that aziridination might share fundamental mechanistic features with olefin cyclopropanation.115 Similar to cyclo-propanation, in which the generally accepted mechanism involves a discrete Cu-carbenoid intermediate, copper-catalyzed aziridation might proceed via a discrete Cu-nitrenoid intermediate as well. 

Reactions with cyclopropene.11 Lithium organocuprates react with the cyclo-propenone ketal 1 (12, 152-154) to form a copper species (a) that behaves as an enolate of a cyclopropanone. Thus it reacts with alkyl halides to form cis-2,3-disubstituted derivatives of 1. 

This chapter will begin with a discussion of the role of chiral copper(I) and (II) complexes in group-transfer processes with an emphasis on alkene cyclo-propanation and aziridination. This discussion will be followed by a survey of enantioselective variants of the Kharasch-Sosnovsky reaction, an allylic oxidation process. Section II will review the extensive efforts that have been directed toward the development of enantioselective, Cu(I) catalyzed conjugate addition reactions and related processes. The discussion will finish with a survey of the recent advances that have been achieved by the use of cationic, chiral Cu(II) complexes as chiral Lewis acids for the catalysis of cycloaddition, aldol, Michael, and ene reactions. 

The metal-catalysed autoxidation of alkenes to produce ketones (Wacker reaction) is promoted by the presence of quaternary ammonium salts [14]. For example, using copper(II) chloride and palladium(II) chloride in benzene in the presence of cetyltrimethylammonium bromide, 1-decene is converted into 2-decanone (73%), 1,7-octadiene into 2,7-octadione (77%) and vinylcyclohexane into cyclo-hexylethanone (22%). Benzyltriethylammonium chloride and tetra-n-butylammo-nium hydrogen sulphate are ineffective catalysts. It has been suggested that the process is not micellar, although the catalysts have the characteristics of those which produce micelles. The Wacker reaction is also catalysed by rhodium and ruthenium salts in the presence of a quaternary ammonium salt. Generally, however, the yields are lower than those obtained using the palladium catalyst and, frequently, several oxidation products are obtained from each reaction [15]. 

Another illustration of the stabilizing effect of phosphines is supplied by cyclo-pentadienylcopper triphenylphosphine, one of the very few examples in which a cyclopentadienyl group is t -bonded to copper (see Fig. 1.6) [52]. 

Raney nickel at 250° and 100-200atm afforded 88% yield of ethyl 3-cyclo-hexylpropanoate [1068], and hydrogenation of the same compound over copper chromite at 250° and 220atm gave 83% yield of 3-phenylpropanol [7057] (p. 158). 

A regio- and stereospecific synthesis of modhephene has also been achieved beginning with the Weiss-Cook reaction As illustrated in Scheme XCVII, cyclo-pentai -l,2-dione can be readily crait l into a-diazo ketone 8(M), copper-catalyz l decomposition of which delivers tricyclic ketone 801. Following the dimethylation of this intermediate, carbomethoxylation was accomplished to give 802 and provide... 

SCHEME 3. Enantioselective copper-catalyzed addition of butylmagnesium chloride to 2-cyclo-hexenone... 

Fenderson, F. F., Kumar, S., Adman, E. T., Liu, M.-Y., Payne, W. J., and LeGall,]. (1991). Amino acid sequence of nitrite reductase A copper protein from Achromobacter cyclo-clastes. Biochemistry 30, 7180-7185. 

Earlier examples of copper(I)-photocatalyzed cycloalkene cyclodimerizations have been summarized in Houben-Weyl, Vol. 4/5a, pp 280-292 as was the copper(I) chloride photocata-lyzed isomerization of cycloocta-1,5-diene to tricyclo[3.3.0.02 6]octane (see Houben-Weyl, Vol. 4/5 a, p 231). This same reaction has recently been used for the preparation of 4-oxatctra-cyclo[6.3.0.02,(,.07,1 L]undecanes.10... 

Cu3N6C15H2], Copper, tris[p-(3,5-dimethyl-1H-pyrazolato-Nl lfi)]tn-, cyclo, [129674-74-4], 31 300... 

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