α-Cupriobenzylideneamines, a novel class of thermally stable organocopper compounds

Koten, G. van; Noltes, J. G.

doi:10.1039/c39720000059

Cited by 48 publications

(54 citation statements)

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“…However, it is assumed that the main structural features for the compounds I-V (multicenter bonded aryl groups; tetranuclear Cu, cluster) are retained in solution. This view seems justified, (I) by the observation that both in the solid and in solution the compounds are tetranuclear and (ii) by the proof [ 20,211 for multicenter bonded aryl groups in the related R4CuzLiz and R,Ag,Li, compounds in solution. As follows from Table 2 and Fig.…”

Section: Mass Spectrometrymentioning

confidence: 98%

Structural characterization of some 2-(dimethylamino)methyl-substituted phenylcopper compounds R4Cu4

Koten¹,

Noltes²

1975

Journal of Organometallic Chemistry

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2-[(Dimethylamino)methyl]phenylcopper and its 5-methyl and 5-methoxy anaiogues are tetrameric in benzene. 5-Methyl-2-[ (dimethylamino)methyl]phenylcopper is tetrameric in the solid state (X-ray structure determination).The bonding in this tetranuclear cluster (Cu-Cu 2.38 A, multicenter bonded aryl groups) is discussed. NMR spectroscopy provides indications that Cu-N coordination okserved in the solid is wea!! in solution. Mass spectra of 2-[(dimethylarnino)methyl] -phenylcopper (RJCuJ) and its 5-methyl analogue (5-hleR)4Cu4 reveal that the CUE cluster in both compounds has considerable stability_ Although the R4Cuq* ions in both spectra are very abundant, the R3Cu4* (even electron species) forms the base peak in the R,Cu, part of the mass spectra. The occurrence in solution of an intercluster exchange between RJCuJ and (5-ivleR)&u,l with formation of the three possible mixed species R(5-MeR)&u,, R,(5-MeR)2Cu, and RJ(5-MeR)C& was confirmed by the mass spectra, which show five patterns in the parent peak region separated by 14 mass units.

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Section: Mass Spectrometrymentioning

confidence: 98%

Structural characterization of some 2-(dimethylamino)methyl-substituted phenylcopper compounds R4Cu4

Koten¹,

Noltes²

1975

Journal of Organometallic Chemistry

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“…Although further study is necessary to disclose the reaction mechanism, the high diastereoselectivity observed in the 1,4-addition of arylcopper reagents is consistent with previous proposals. 2,6) Since it is assumed that the conjugate addition takes place via the s-cis conformation 6) of a,b-unsaturated tertiary amide 1, a diarylcopper reagent, which would be dimeric, 14) could attack preferentially from the C(3)-Re face of transition state A, affording 4 as shown in Fig. 1.…”

Section: )mentioning

confidence: 99%

1,6-Asymmetric Induction during the Conjugate Addition of Arylcopper Reagents to a Chiral Sulfinyl-Substituted Pyrrolyl .ALPHA., .BETA.-Unsaturated Amide.

Arai

Ueda

Xie

et al. 2001

CHEMICAL & PHARMACEUTICAL BULLETIN

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Organocopper conjugate addition to a,b-unsaturated carbonyl systems represents an important area for organic synthesis.2) To overcome difficulties encountered with 1,4-addition to unsaturated aldehydes and esters due to competing 1,2-addition and to unsaturated amides owing to low reactivity of the C-C double bond in their carbonyl compounds, Lewis acid-and trimethylsilyl halide-mediated organocopper reagents have been devised. Moreover, to enhance the reactivity of the organocopper reagents, various types of reagents including the higher-order cuprates have also been developed.Asymmetric organocopper-conjugate addition reactions have been carried out by the use of 1) chiral auxiliaries in either the copper reagent or the a,b-unsaturated carbonyl compound, 2) chiral ligands, 3) a chiral catalyst, or 4) a chiral solvent. Compared with other asymmetric additions of cuprates, methods employing a conjugate acceptor with a chiral auxiliary are most reliable and promising in view of high performance because selectivities in the reactions by other methods are dependent on a large number of factors, including substrate and cuprate structure, solvent, 3) and the presence of added salts. Asymmetric conjugate addition of organometallic species to a,b-unsaturated enone with a chirally sulfinylated auxiliary has been developed by Posner et al.4) who reported highly stereoselective 1,4-additions of Grignard reagents with or without a Lewis acid, and organocuprates. On the other hand, studies of asymmetric organocopper-conjugate additions using a,b-unsaturated amides are not common since the amides are essentially inert toward organometallic reagents 5) unless another activating group is introduced in these molecules. To circumvent the low reactivity of the C-C double bond in these amides, activated amides (X*ϭchiral auxiliary, XϭC, N, O) such as the N-enoyl lactams 6) (A, B) and the N-enoyl sultams 7) (C), or the use of trimethylsilyl chloride (TMSCl) as an additive for the amide (D) 8) have been devised to date. In the course of our studies on asymmetric reactions using chiral sulfoxides, we recently reported the highly diastereoselective Diels-Alder reaction of a,b-unsaturated amides 1 and 2, which are obtained, respectively, from a chiral sulfinyl auxiliary 3 and (E)-cinnamoyl-and crotonoyl chloride. 9) Encouraged by the excellent results with both the reactivity and the diastereoselectivity of 1 in the cycloaddition, we were intrigued by the conjugate addition of an organocopper reagent to these amides. To evaluate the reactivity and selectivity in organocopper-conjugate addition, we planned the reaction using the a,b-unsaturated amides. Here we describe the diastereoselective conjugate addition of organocopper reagents to 1 and 2 with a remote chiral auxiliary 3. 10)First, we undertook the conjugate addition of methylcopper and dimethyl cuprate derived from methyllithium and copper(I) iodide to cinnamide 1 (Chart 1). The results are December 2001 Chem. Pharm. Bull. 49(12) 1609-1614 (2001) 1609 * To whom correspondenc...

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“…Recently van Koten et al (6) have used the chiral labelling technique (10) to show that the Hg-N coordination is stable on the nmr time scale at -70°C in LHgX compounds (X = CI, OAc), but becomes labile at higher temperatures.…”

Section: Nuclear Magnetic Resonance Spectroscopymentioning

confidence: 99%

Zinc(II) and cadmium(II) compounds with the 2-[(dimethylamino)methyl]phenyl ligand

Osman¹,

Steevensz²,

Tuck³

et al. 1984

Can. J. Chem.

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α-Cupriobenzylideneamines, a novel class of thermally stable organocopper compounds

Cited by 48 publications

References 0 publications

Structural characterization of some 2-(dimethylamino)methyl-substituted phenylcopper compounds R4Cu4

Structural characterization of some 2-(dimethylamino)methyl-substituted phenylcopper compounds R4Cu4

1,6-Asymmetric Induction during the Conjugate Addition of Arylcopper Reagents to a Chiral Sulfinyl-Substituted Pyrrolyl .ALPHA., .BETA.-Unsaturated Amide.

Zinc(II) and cadmium(II) compounds with the 2-[(dimethylamino)methyl]phenyl ligand

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