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1.
The reaction of [R-(R,R)]-(+)589-[(η5-C5H5){1,2-C6H4(PMePh)2}Fe(NCMe)]PF6 with (±)-AsHMePh in boiling methanol yields crystalline [R-[(R)-(R,R)]-(+)589)-[(η5-C5H5){1,2-C6H4(PMePh)2}Fe(AsHMePH)PF6, optically pure, in ca. 90% yield, in a typical second-order asymmetric transformation. This complex contains the first resolved secondary arsine. Deprotonation of the secondary arsine complex with KOBut at −65°C gives the diastereomerically pure tertiary arsenido-iron complex [R-[(R),(R,R)]]-[((η5-C5H5){1,2-C6H4(PMePh)2}FeAsMePh] · thf, from which optically pure [R-[(S),(R,R)]]-(+)589-[(η5-C5H5){1,2-C6H4(PMePh)2}Fe(AsEtMePh)PF6 is obtained by reaction with iodoethane. Cyanide displaces (R)-(−)589-ethylmethylphenylarsine from the iron complex, thereby effecting the asymmetric synthesis of a tertiary arsine, chiral at arsenic, from (±)-methylphenylarsine and an optically active transition metal auxiliary.  相似文献   

2.
A series of new imidazolyl and 1H-1,2,4-triazolyl derivatives of (η6-arene)(η5cyclopentadienyl)iron(II) salts have been prepared by reaction of the corresponding chloroarene complexes with the sodium salts of the heterocycles. Good yields of N-substituted products were obtained in all cases under very mild conditions. In contrast to substitution by primary and secondary amines, both chlorines were displaced from [(η5-1,2-dichlorobenzene)(η5-Cp)Fe][PF6], indicating electron withdrawal by the imidazolyl and triazolyl groups. Detailed 1H and 13C NMR analysis confirmed this point. NOE difference spectra were used for 13C assignments, and evidence for conformational isomers in the 1,2-disubstituted complexes is presented.  相似文献   

3.
Acylrhodium(III)-η3-1-ethylallyl complex (7) was prepared by the reaction of 8-quinolinecarboxaldehyde (3) and 1,4-pentadienerhodium(I) chloride (2) by C---H bond activation, followed by hydrometallation, and double bond migration. Higher concentrations of pyridine as coordinating ligand transforms η3-1-ethylallylrhodium(III) complexes (8a,8b) into η1-pent-2-enylrhodium(III) complex (11a). Acylrhodium(III)-η3-syn,anti-1,3-dimethylallyl complex (14) was also prepared from 1,3-pentadienerhodium(I) chloride (16) and 3. The reductive elimination of acylrhodium(III)-η1- and -η3-1-alkylallyl complexes by trimethylphosphite gives various β,γ-unsaturated ketones.  相似文献   

4.
An unexpected [2+2]-cycloaddition occured in the reaction of 4-methyldithieno-[3,4-6:3′,2′-d]pyridinium iodide (3)with two equivalents of DMAD, giving 4-(trans-1,2-dicarbomethoxy-2- iodovinyl)-5-methyl-6,7-dicarbomethoxy-4,5-dihydrothieno [23-c]quinoline (4) in 54% yield. 4 is formed via 4-methyl-5-(trans-1,2-dicarbomethoxy-2-iodo-4,5-dihydrothieno [3,4-b:3′,2′-d]pyridine (16), followed by [2+2]-cycloaddition. The primary adduct rearranges via a thiepin to an episulfide which eliminates sulfur to give 4.  相似文献   

5.
A tridentate Schiff base ligand [(CH3)2NCH2CH2N=C(CH3)C6H4OH)] (LH) has been synthesized from 2-hydroxyacetophenone and 2-dimethylaminoethylamine. This ligand forms the neutral complexes [Co(L)(N3){o-(CH3C=O)C6H4O}] (1) and [Co(L)(SCN){o-(CH3C=O)C6H4O}]·1/2H2O (2) in presence of equivalent amount of Co(II) acetate, and sodium azide for 1 and sodium thiocyanate for 2. The complexes have been characterized by spectroscopic and crystallographic methods. The coordination geometry around Co(III) in both the complexes is distorted octahedral with one tridentate ligand L, one bidentate 2-hydroxyacetophenone and one monodentate azide for 1 and thiocyanate for 2. The azide and thiocyanate ligands in the two complexes occupy different positions relative to the coordination sites of L.  相似文献   

6.
Reaction of the activated mixture of Re2(CO)10, Me3NO and MeOH with a 1:1 mixture of rac (d/l)- and meso-1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane (hptpd) yields a mixture of (d/l)- and meso-[{Re2(μ-OMe)2(CO)6}2(μ,μ′-hptpd)] 1. The diastereomers can be easily separated by selective dissolution of d/l-1 in benzene, and give clearly distinguishable 1H- and 31P-NMR spectra. The fluxional behavior of d/l-1 in solution has been studied by variable-temperature 1H- and 31P-{1H}-NMR spectroscopy. The crystal structures of both d/l- and meso-1 have been determined. Both molecules consist of two {Re2(μ-OMe)2(CO)6} moieties which are bridged by the two P---CH2---CH2---P moieties of the hptpd ligand. Whilst the molecules of meso-1 possess crystallographic i-symmetry, those of d/l-1 do not have any crystallographic symmetry. These diastereomers therefore give clearly distinguishable Raman spectra in the solid state. Reaction of tris[2-(diphenylphosphino)ethyl]phosphine (tdppep) with the activated mixture affords the complex [{Re2(μ-OMe)2(CO)6}(μ,η2-tdppep)] 2, and the analogous reaction involving bis[2-diphenylphospinoethyl)phenylphosphine (triphos) gives [{Re2(μ-OMe)2(CO)6}(μ,μ′,η3-triphos){Re2(CO)9}] 3 and [{Re2(μ-OMe)2(CO)6}(μ,η2-triphos)] 4.  相似文献   

7.
The reactions of η5-Cp*M(CO)3Na (M = Mo, W) with ,′-p-, m- and o-dichloro-xylenes yielded p-, m- and o-xylyl bridged dinuclear complexes of η5-Cp*M(CO)3 in high yields. All of such new complexes are stable to air and water, even stable in dilute acids and bases.  相似文献   

8.
Pentacarbonyl(diethylaminocarbyne)chromium tetrafluoroborate, [(CO)5− CrCNEt2]BF4 (I), reacts with PPh3 with substitution of CO and formation of trans-tetracarbonyl(diethylaminocarbyne)triphenylphosphanechromium tetra-fluoroborate, trans-[PPh3(CO)4CrCNEt2]BF4 (III). Substitution of CO by PPh3 in neutral trans-tetracarbonyl(halo)(diethylaminocarbyne)chromium complexes, trans-X(CO)4CrCNEt2 (IVa: X = Br, IVb: X = I), leads in a reversible reaction to the corresponding tricarbonyl complexes, mer-X(PPh3)(CO)3− CrNEt2 (V), PPh3 occupying the cis-position to the carbyne ligand. With PPh3 in large excess both reactions follow a first-order rate law. This as well as the activation parameters (ΔH≠ = 104–113 kJ mol−1, ΔS≠ = 64–71 J mol−1 K−1) indicate a dissociative mechanism.  相似文献   

9.
The reaction of N-(3,4-dichlorophenethyl)-N-methylamine (1) with 3-chloromethyl-5-phenyl-1,2,4-oxadiazole (2) was investigated. Employment of an equimolar amount of 1 and 2 in the presence of potassium carbonate led to the expected tertiary amine 3 (N-[(3,4-dichlorophenyl)ethyl]-N-methyl-N-[(5-phenyl-1,2,4-oxadiazol-3-yl)methyl]amine), whereas an excess of 1 and prolonged reaction time resulted in ring fission of the oxadiazole system in 3 and finally in the formation of N′-benzoyl-N-[(3,4-dichlorophenyl)ethyl]-N-methylguanidine (4) and N,N′-bis[(3,4-dichlorophenyl)ethyl]-N,N′-dimethylmethanediamine (5). The structures of products 3–5 were determined by means of 1H and 13C NMR-spectroscopy, mass spectrometry and IR-spectroscopy, for 3 (as picrate) and 4 also X-ray structure analysis was employed. A possible mechanism of the reaction pathway leading to compounds 4 and 5 is proposed.  相似文献   

10.
A new series of rigid-rod alkynylferrocenyl precursors with central fluoren-9-one bridge, 2-bromo-7-(2-ferrocenylethynyl)fluoren-9-one (1b), 2-trimethylsilylethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (2) and 2-ethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (3), have been prepared in moderate to good yields. The ferrocenylacetylene complex 3 can provide a direct access to novel heterometallic complexes, trans-[(η5-C5H5)Fe(η5-C5H4)CCRCCPt(PEt3)2Ph] (4), trans-[(η5-C5H5)Fe(η5-C5H4)CCRCCPt(PBu3)2CCRCC(η5-C5H4)Fe(η5-C5H5)] (5), [(η5-C5H5)Fe(η5-C5H4)CCRCCAu(PPh3)] (6) and [(η5-C5H5)Fe(η5-C5H4)CCRCCHgMe] (7) (R=fluoren-9-one-2,7-diyl), following the CuI-catalyzed dehydrohalogenation reactions with the appropriate metal chloride compounds. All the new complexes have been characterized by FTIR, 1H-NMR and UV–vis spectroscopies and fast atom bombardment mass spectrometry. The solid state molecular structures of 3, 5, 6 and 7 have been established by X-ray crystallography. The redox chemistry of these mixed-metal species has been investigated by cyclic voltammetry and oxidation of the ferrocenyl moiety is facilitated by the presence of the heavy metal centre and increased conjugation in the chain through the ethynyl and fluorenone linkage units.  相似文献   

11.
Reaction of phenyl magnesium bromide with the ,β-unsaturated ketone 3-methyl-2,3,4,5,6,7-hexahydroind-8(9)-en-1-one, followed by an aqueous work-up, generates the pro-chiral tetra-substituted cyclopentadiene, 1-phenyl-3-methyl-4,5,6,7-tetrahydroindene, CpH, a precursor to the η5-cyclopentadienyl ligand in (Cp)2Fe and [(Cp)Fe(CO)]2(μ-CO)2. Both complexes were generated as mixtures of rac-(RR and SS)- and meso-(RS)-isomers, and in either case pure meso-isomer was isolated by crystallisation and characterised by single crystal X-ray structure, both molecules having crystallographic Ci symmetry. Reduction with Na/Hg cleaves meso-(RS)-[(Cp)Fe(CO)]2(μ-CO)2 and the resulting mixture of (R)- and (S)-[(Cp)Fe(CO)2] anions reacts with MeI to give racemic (Cp)Fe(CO)2Me, which was characterised by the X-ray crystal structure. The Cp ligand is more electron donating than (η-C5H5) as revealed by the reduction potential of the (Cp)2Fe+/(Cp)2Fe couple, E°=−0.127 V (vs. Ag  AgCl). Reaction of LiCp with ZrCl4 yields the zirconocene dichloride [Zr(Cp)2Cl2] as mixture of rac- and meso-isomers, from which pure rac-isomer is obtained as a mixture of RR and SS crystals by recrystallisation. The reaction of rac-[Zr(Cp)2Cl2] with LiMe gives rac-[Zr(Cp)2Me2]. The structures of RR-[Zr(Cp)2Cl2] and rac-[Zr(Cp)2Me2] have been determined by X-ray diffraction. The structural studies reveal the influence of the bulky substituted cyclopentadienyl ligand on the metal---Cp distances and other metric parameters.  相似文献   

12.
CpIr(η4-C6H6) (2) has been obtained in high yield by a four-step synthesis. Thermal reaction of 2 with CpCO(C2H4)2 and photochemical reaction of 2 with CpRh(C2H4)2 or CpRh(C2H4)2 give the compounds μ-(η3: η3-C6H6)CoIrCp2 (3), μ-(η3: η3-C6H6)RhIrCp2 (4), and μ-(η3: η3-C6H6)(RhCp)(IrCp) (5), respectively. The X-ray crystallography data of 3 and 4 reveal a boat-shaped conformation of the synfacially bridging benzene ligand with a rather long Co---Ir bond distance in 3 and a relatively short Rh---Ir bond length in 4 which are caused by almost constant folding angles of the benzene unit. The dynamic behaviour of the benzene bridge was investigated by NMR spectrometry.  相似文献   

13.
Zhou L  Wang J  Zhang Y  Yao Y  Shen Q 《Inorganic chemistry》2007,46(14):5763-5772
The synthesis and structures of a series of lanthanide(II) and lanthanide(III) complexes supported by the amido ligand N(SiMe3)Ar were described. Several lanthanide(III) amide chlorides were synthesized by a metathesis reaction of LnCl3 with lithium amide, including {[(C6H5)(Me3Si)N]2YbCl(THF)}2.PhCH3 (1), [(C6H3-iPr2-2,6)(SiMe3)N]2YbCl(mu-Cl)Li(THF)3.PhCH3 (4), [(C6H3-iPr2-2,6)(SiMe3)N]YbCl2(THF)3 (6), and [(C6H3-iPr2-2,6)(SiMe3)N]2SmCl3Li2(THF)4 (7). The reduction reaction of 1 with Na-K alloy afforded bisamide ytterbium(II) complex [(C6H5)(Me3Si)N]2Yb(DME)2 (2). The same reaction for Sm gave an insoluble black powder. An analogous samarium(II) complex [(C6H5)(Me3Si)N]2Sm(DME)2 (3) was prepared by the metathesis reaction of SmI2 with NaN(C6H5)(SiMe3). The reduction reaction of ytterbium chloride 4 with Na-K alloy afforded monoamide chloride {[(C6H3-iPr2-2,6)(SiMe3)N]Yb(mu-Cl)(THF)2}2 (5), which is the first example of ytterbium(II) amide chloride, formed via the cleavage of the Yb-N bond. The same reduction reaction of 7 gave a normal bisamide complex [(C6H3-iPr2-2,6)(SiMe3)N]2Sm(THF)2 (8) via Sm-Cl bond cleavage. This is the first example for the steric effect on the outcome of the reduction reaction in lanthanide(II) chemistry. 5 can also be synthesized by the Na/K alloy reduction reaction of 6. All of the complexes were fully characterized including X-ray diffraction for 1-7.  相似文献   

14.
The enantioselective hydrolysis of (3RS,4RS)-trans-4-(4′-fluorophenyl)-6-oxo-piperidin-3-ethyl carboxylate (±)-2 was effected using a commercial preparation of lipase from C. antarctica A (CAL-A). We found that the hydrolytic activity of the lipase (immobilized on a number of very different supports) with this substrate was negligible. However, a contaminant esterase with Mw of 52 KDa from this commercial preparation exhibited much higher activity with (±)-2. This enzyme was purified and immobilized on PEI-coated support and the resulting enzyme preparation was highly enantioselective in the hydrolysis of (±)-2 (E >100), hydrolyzing only the (3S,4R)-(−)-3, which is a useful intermediate for the synthesis of pharmaceutically important (−)-paroxetine. Optimization of the reaction system was performed using a racemic mixture with a substrate concentration of 50 mM. This enzyme preparation was used in three reaction cycles and maintained its catalytic properties.  相似文献   

15.
We have prepared analogues of (2S,4S)-N-(t-butoxycarbonyl)-4-(diphenylphosphino)-2-[(diphenylphsphino)methyl]pyrrolidine (BPPM), bearing para-dimethyl-amino groups to prove the utility of our designing concept with regard to electronic effects of the phosphino groups on the enantioselectivity and the activity of the rhodium complex catalysts. Their rhodium complexes are much more effective than those of BPPM and (2S,4S)-N-(t-butoxycarbonyl)-4-(dicyclohexylphosphino)-2-[(diphenylphosphino)methyl]pyrrolidine (BCPM) for the asymmetric hydrogenation of dimethyl itaconate. The hydrogenation has also been used successfully in an efficient asymmetric synthesis of the key intermediate of new human renin inhibitors.  相似文献   

16.
In the reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr (isopropyl), chex (cyclohexyl)) with BI3 the Lewis acid attacks the triphenylstannyl ligand. Substitution of a phenyl for a iodine group leads to equilibrium mixtures of rhenium carbene complexes of general formula cis-(CO)4(SnPh3−χIχ)Re[C(OEt)NR2] (χ = 1−3; R = ipr, chex). By changing the solvent and ratio of can be shifted such that only one major product is formed. Thus this reaction pathway can be used for the preparation of cis-(CO)4(SnPhI2)Re[C(OEt)NR2] (R = ipr, chex). Even when a large excess of BI3 is present electrophilic attack by the Lewis acid on the carbene ligand is not observed.

Synthesis of cis-(CO)4(SnPh3−χIχ)Re[C(OEt)NR2] (χ = 1−3; R --- ipr, chex) can be achieved in high yield by reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr, chex) with one, two or three equivalents of HI. This reaction, with successive rupture of the tin-carbon bonds in the triphenylstannyl ligand and the simultaneous formation of benzene, affords the desired substitution product irreversibly. Reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr, chex) with I2 gives the compounds, cis-(CO)4(SnI3)Re[C(OEt)NR2] (R = ipr, chex), in relatively low yields.  相似文献   


17.
The reaction of epichlrohydrine (fx45-1) with lithium-diphenylphosphide (LiP(Ph)2 yields the alcohol (HOCH(CH2P(Ph)2)2) 1 in a stereochemically controlled reaction. To prove the constitution and coordination ability of 1, the compound has been used to synthesise the homoleptic bisdiphosphine-rhodium complexes trans/cis-[(1)2Rh1]B(Ph)42a, b. The X-ray structure of 2b shows a significant tetrahedral distortion of the planar coordination geometry theoretically favoured for a tetracoordinate metal d8 coordination compound. The diphosphino alcohol 1 easily reacts with chiral phosphorchloridites X2PCI(X2 = 2 R, 4R-2,4-pentanedioxy-3a); (±)- and R-2,2′-bi-1-naphthoxy-(3b)) to yield chiral-racemic as well as enantiomerically pure mixed donor group tripodal ligands (X2POCH(CH2P(Ph)2)2) 5a, b containing both phosphite and phosphine donor groups. The identity of these compounds has been proven by 1H-, 31P- and 13C-NMR spectroscopy, mass-spectra and microanalysis. The coordination capabilities of these novel tripod ligands are demonstrated by the synthesis and characterisation of the chiral rhodium-cyclooctadiene complexes {[(5a,b)Rh1(COD)]PF6} 6a,b, which show the typical hetero-bicyclooctane tripod metal cage of this type of tripod metal template. The rhodium complexes 6a,b are catalysts for the hydrogenation of prochiral olefines. Their activity is not too high and the enantioselectivity is low. The trihapto-coordination of the tripodal ligands is more of an impediment for this type of catalytic transformation.  相似文献   

18.
The butadienyl complexes formed by the reaction of trans-(R1)CH=CHCCR2 (R1, R2 = SiMe3, tBu, Me, Et) with RuCl(CO)H(PPh3)3 exhibit unique structures: instead of taking the 18-electron configuration of the metal by conventional η3-coordination of the butadienyl ligand, they shift significantly to the 16-electron η1-coordination state.  相似文献   

19.
13C and 31P{1H} NMR data at low temperature prompted us to characterize cis-[Rh(CO)2(PR3)Cl] (3) (3a, PR3 = PPh3; 3b, PR3 = PMe2Ph), as surprisingly stable products of the reaction between [{Rh(CO)2(μ-Cl)}2] (1) and tertiary phosphines in toluene (P : Rh = 1). Every attempt to isolate solid 3a led to the cis- and trans- halide-bridged dimers [{Rh(CO)2(μ-Cl)}2] (5a) and 6a which are formed from 3a by slow decarbonylation, a process which is greatly accelerated by the evaporation of the solvent under vacuum.

The analogous reaction of 1 with dimethylphenylphosphine follows a similar pathway; in this case, however, low temperature NMR spectra allowed us to characterize the pentacoordinated dinuclear species [{Rh(CO)2(μ-Cl)}2] (2b) as the unstable intermediate of the bridge-splitting process.

The reaction of 3 with a second equivalent of phosphine (P : Rh = 2) leads, at room temperature, to the well known product trans-[Rh(CO)(PR3)2Cl] (8) accompanied by evolution of CO; however our data show that when the reaction is performed at 200 K, decarbonylation is prevented and spectroscopic evidence of trigonal bipyramidal pentacoordinate [Rh(CO)2(PR3)2Cl] (7), stable only at low temperature, can be obtained.  相似文献   


20.
Katmusi Kotera 《Tetrahedron》1961,12(4):248-261
Hydrogenation of -anhydrodihydrocaranine (V) or anhydrocaranine (VII) with Adams catalyst in acetic acid or the Hauptmann reduction of -dihydrocaranone (XX) yielded (—)γ-lycorane (XVII). Catalytic reduction of β-anhydrodihydrocaranine (IX) with palladium-carbon in ethanol gave (+)γ-lycorane (XVIII), while with Adams catalyst in acetic acid it afforded (+)δ-lycorane (XIX) along with (—)β-lycorane (III). Reduction of anhydrocaranine in ethanol gave (±)γ-lycorane which was also obtained by hydrogenation of anhydrolycorine (X). Based on these findings, the configurational structures of -, β-, γ- and δ-lycorane were established and the configuration of dihydrolycorine was confirmed.  相似文献   

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