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1.
Even late transition metal complexes function as active and selective catalysts for α‐olefin polymerization. The discovery of a highly active family of catalysts 1 based on iron, a metal that had no previous track record in this field, has highlighted the possibilities for further new catalyst discoveries. As a result, an intense search has developed for new‐generation catalysts, in both academic and industrial research laboratories. R1=H, Me; R2=Me, iPr; R3=H, Me, iPr; R4=H, Me; X=halide.  相似文献   

2.
Enantiomeric excesses of up to 99 % could be obtained in the synthesis of the biologically interesting acylated α-aminophosphinic acids 1 (R1=Me, Ph; R2=H, Me, Et; R3=H, F, iPr) by asymmetric hydrogenation with rhodium complex catalysts and subsequent hydrolysis [Eq. (1)]. cod=1,5-cyclooctadiene.  相似文献   

3.
Twelve novel 3-alkyl[aryl]-1-carboxamides-5-trichloromethyl-5-hydroxy-4,5-dihydro-lH-pyrazole have been synthesized in good yields (72–90%) using environmentally benign microwave-induced techniques. The compounds were synthesized from the cyclocondensation of 4-alkoxy-1,1,1-trichloro-3-alkyl[aryl]-2-ones [Cl3CC(O)C(R2) = C(R1)OR, where R = Me, Et; R1 = H, Me, Et, Pr, i-Pr, i-Bu, t-Bu, Ph, Ph-4-NO2, Ph-4-F, Ph-4-Cl, Ph-4-Br; and R2 = H, Me] with semicarbazide hydrochloride in the presence of pyridine and using methanol/water (3:1 v/v) as the solvent. The advantages of using microwave irradiation, rather than a conventional method, were demonstrated.  相似文献   

4.
Two series of 5-trichloromethylisoxazoles were synthesized from the cyclocondensation of 1,1,1-trichloro-4-methoxy-3-alken-2-ones [Cl3CC(O)C(R2) = C(R1)OMe, where R1 = H, Me, Et, Pr, iso-Pr, cyclo-Pr, Bu, terc-Bu, CH2Br, CHBr2, CH(Me)SMe, (CH2)2Ph, and Ph, and R2 = H; R1 = H and R2 = Me and Et; R1 and R2 = -(CH2)4- and -(CH2)5-; and R1 = Et and Ph and R2 = Me] with hydroxylamine hydrochloride through a rapid one-pot reaction in water. The 5-trichloromethyl-4,5-dihydroisoxazoles were aromatized by reaction with concentrated sulfuric acid to obtain the respective 5-trichloromethylisoxazoles. Their structures were confirmed by elemental analysis, 1H/13C nuclear magnetic resonance, and electron impact mass spectroscopy. Crystal structure analysis for 5-triclhoromethyl-5-hydroxy-3-propyl-4,5-dihydroisoxazole (2d) and 5-trichloromethyl-5-hydroxy-3,4-hexamethylene-4,5-dihydroisoxazole (2o) is presented. The antimicrobial activities of the 5-trichloromethyl-4,5-dihydroisoxazole derivatives were examined using the standard twofold dilution method against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and yeasts (Candida spp. and Cryptococcus neoformans). All of the tested 5-trichloromethyldihydroisoxazoles exhibited antibacterial and antifungal activities at the tested concentrations.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.  相似文献   

5.
Asymmetric formylation of aromatic compounds is virtually unexplored. We report the synthesis and evaluation of a library including 20 new chiral formamides in the kinetic resolution of 7,8‐dipropyltetrathia[7]helicene, affording the corresponding formyl‐ or diformylhelicenes in up to 73 % ee, making enantiopure compounds available by recrystallisation. With the N,N‐disubstituted formamides used in this study, the best enantioselectivity has been achieved with R1=iPr, R2=Me, R3=H, R4=1‐naphthyl or its 1‐pyrenyl equivalent.  相似文献   

6.
Variations in the ligand structure of homogeneous late transition metal catalysts through judicious choice and location of substituent is the foremost strategy in improving their catalytic performance for ethylene polymerization. In this contribution, symmetrical and unsymmetrical bis(imino)pyridylcobaltous chloride complexes adorned with nitro and benzhydryl groups {2‐[1‐(2,6‐dibenzhydryl‐4‐nitrophenylimino)ethyl]‐6‐[1‐(alkylphenylimino)ethyl]pyridylcobaltous chloride (alkyl: R1 = Me and R2 = H, Co1 ; R1 = Et and R2 = H, Co2 ; R1 = iPr and R2 = H, Co3 ; R1 and R2 = Me, Co4 ; R1 = Et and R2 = Me, Co5 ; R1 = benzhydryl and R2 = NO2, Co6 )} have been prepared and applied as catalysts for ethylene polymerization. The molecular structure of Co1 and Co2 revealed the unequal steric protection of the cobalt center induced by bis(imino)pyridine chelate. In the presence of methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) activators at different ethylene feeding rates (1 and 10 atm), catalysts Co1 – Co5 displayed high activities at 10 atm ethylene and produced strictly linear polyethylene (PE) with high molecular weight, Co2 /MMAO being the most highly active catalytic system showing the highest activity of 9.41 × 106 g of PE (mol of Co)?1 h?1 which is three times higher than that of prototypal cobalt catalyst ( Co0 ) under identical conditions. Moreover, high melt temperature and unimodal molecular weight distribution are the characteristics of the resulting polyethylene.  相似文献   

7.
《化学:亚洲杂志》2017,12(2):239-247
Five bis(quinolylmethyl)‐(1H ‐indolylmethyl)amine (BQIA) compounds, that is, {(quinol‐8‐yl‐CH2)2NCH2(3‐Br‐1H ‐indol‐2‐yl)} ( L1H ) and {[(8‐R3‐quinol‐2‐yl)CH2]2NCH(R2)[3‐R1‐1H ‐indol‐2‐yl]} ( L2–5H ) ( L2H : R1=Br, R2=H, R3=H; L3H : R1=Br, R2=H, R3=i Pr; L4H : R1=H, R2=CH3, R3=i Pr; L5H : R1=H, R2=n Bu, R3=i Pr) were synthesized and used to prepare calcium complexes. The reactions of L1–5H with silylamido calcium precursors (Ca[N(SiMe2R)2]2(THF)2, R=Me or H) at room temperature gave heteroleptic products ( L1, 2 )CaN(SiMe3)2 ( 1 , 2 ), ( L3, 4 )CaN(SiHMe2)2 ( 3 a , 4 a ) and homoleptic complexes ( L3, 5 )2Ca ( D3 , D5 ). NMR and X‐ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L3–5 )CaN(SiMe3)2) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of (E )‐1,2‐bis(8‐isopropylquinol‐2‐yl)ethane.  相似文献   

8.
Without any formation of stereoisomers , the intramolecular pinacol cyclization of 1 —planar chiral mono-Cr(CO)3 complexes of 1,1′-biphenyls with carbonyl functionalities at the 2- and 2′-positions—with samarium diiodide gives cyclic trans-1,2-diols 2 . Upon exposure to sunlight, the chromium-complexed diols 2 produce optically pure chromium-free trans-diols 3 . Similarly, the corresponding enantiomerically pure trans-1,2-diamines and amino alcohols are obtained from the planar chiral chromium complexes of biphenyls with diimino or keto-imino functionalities. R1=H, OMe; R2=H, Me; R3=H, Me.  相似文献   

9.
Monomeric bis(isopropoxy) titanium complexes LTi(Oi Pr)2 (L =  ─ OC6H2–4‐R1–6‐R2–2‐CH2N[(CH2)2N(R3)2]CH2–4‐R4–6‐R5‐C6H2O ─ , R1 = R2 = t Bu, R3 = Et, R4 = R5 = Cl, (L1)Ti(Oi Pr)2; R1 = R2 = Me, R3 = Et, R4 = R5 = Me, (L2)Ti(Oi Pr)2; R1 = R2 = t Bu, R3 = Et, R4 = OMe, R5 = t Bu, (L3)Ti(Oi Pr)2; R1 = R4 = OMe, R3 = Et, R2 = R5 = t Bu, (L4)Ti(Oi Pr)2; R1 = R2 = t Bu, R3 = Me, R4 = OMe, R5 = t Bu, (L5)Ti(Oi Pr)2) supported by amine bis(phenolate) ligands were synthesized and characterized using NMR spectroscopy and elemental analysis. The solid‐state structure of (L3)Ti(Oi Pr)2 was determined using single‐crystal X‐ray diffraction. (L1–5)Ti(Oi Pr)2 were all found to initiate the ring‐opening polymerization of l ‐lactide and rac ‐lactide in a controlled manner at 110–160°C. As shown by kinetic studies, (L1)Ti(Oi Pr)2 polymerized l ‐lactide faster than did (L2–5)Ti(Oi Pr)2. In addition, good number‐average molecular weight and narrow polydispersity index (1.00–1.71) of polymers were also obtained. The microstructure of the polymers and a possible mechanism of coordination–insertion of polymerization were evidenced by MALDI‐TOF and 1H NMR spectra of the polylactides.  相似文献   

10.
Racemiccloso-rhodacarboranes,vis. closo-(η3,2-C7H3-2-CR 2 1 )-1-R2-2-R3-3,1,2-RhC2B9H9 (R1=R2=R3=H; R1=H, R2=R3=Me; R1=R2=R3=Me) and (closo-2,2-(η3,2-C7H7-2-CH2)-2,1,7-RhC2B9H11), were successfully separated into enantiomers by high-performance liquid chromatography (HPLC). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 759–761, April, 2000.  相似文献   

11.
《Tetrahedron: Asymmetry》2001,12(6):847-852
The bioreduction of α-methyleneketones, R1C(O)C(CH2)R2 (R1=Me, Et, Pr, iso-Bu, Ph, CH2CH2Ph; R2=Cl, Me, Et, n-Pr, iso-Pr, n-Bu, n-C6H13, Ph, CH2Ph), was mediated by baker's yeast (Saccharomyces cerevisiae) to obtain the corresponding α-methylketones. The R1 and R2 groups had a significant influence on the rate and enantioselectivity of the reductions. The rate of CC bond reduction was higher than that of CO bond reduction. Only α-methyleneketones having R1=Me yielded α-methylketones in high enantioselectivity with e.e.s of 88–99%.  相似文献   

12.
The reactions between secondary carbosilanes 1-3 and 1-propylbiguanide/1-phenylbiguanide, H6bigR proceed via SiH/NH dehydrocoupling and afford 1,4-bis(silyl)-5-propyl/phenylbiguanides with the general formula (R1R22SiCH2CH2SiMeH)2·H4bigR, [R1=Ph, R2=Me, R=nPr (4), R=Ph (5); R1=Me, R2=Ph, R=nPr (6), R1=R2=Et, R=Ph (7)]. These compounds represent a new family of pentacoordinate silicon derivatives comprising of [Si-N-C-N-C-N] chelate ring and have been characterized by elemental analysis, FAB mass, IR and multinuclear (1H, 13C and 29Si) NMR spectral studies.  相似文献   

13.
The series of bidentate N^N iron(II) and cobalt(II) complexes containing 8-(1-aryliminoethylidene) quinaldine derived ligands, 8-[2,6-(R1)2-4-R2-C6H2NC (Me)]-2-Me-C10H5N, were synthesized and characterized by elemental and spectroscopic techniques. The molecular structures of Co1 (R1 = Me, R2 = H), Co3 (R1 = iPr, R2 = H) and Co4 (R1 = R2 = Me) were confirmed as the distorted tetrahedral by single crystal X-ray diffraction. On treatment with modified methylaluminoxane (MMAO), these complexes exhibited good catalytic activities of up to 5.71 × 105 g mol−1(Fe) h−1 for the ethylene dimerization at 30 °C under 10 atm of ethylene, in which iron pre-catalysts produced butenes with a high selectivity for α-butene. The correlation between metal complexes, catalytic activities and the product formed were investigated under various reaction parameters.  相似文献   

14.
Abstract

P.P-Dialkylthiophosphinsäureamide R2P(S)NHR' (R=Me, 'Pr, 'Bu; R'=Me, Et, iPr. cHex. tBu. Ph. etc.) wurden erhalten durch Umsetzung von R2PNHR' mit Schwefel oder durch Reaktion von Me2P(S)CI mit primaren Aminen. Ihre 31P- und 13C-NMR-Spektren werden diskutiert. Insbesondere die Di-t-butylthiophosphinsäureamide sind auszilg;ergewöhnlich stabil gegen Hydrolyse und Luftsauerstoff. P,P-Dialkylthiophosphinic acid amides R2P(S)NHR' (R=Me. iPr. tBu; R'=Me, Et, iPr, cHex. tBu, Ph. etc.) have been obtained by reaction of the corresponding aminophosphines with sulfur or by reaction of dimethylthiophosphorylhalides with primary amines. Their 31P- and 13C-NMR spectra are discussed. The di-t-butylthiophosphinic compounds proved to be remarkably stable against moisture and oxygen.  相似文献   

15.
Treatment of 2-X-substituted pyrazines [X = H, Me, Et, Pr, i-Pr, t-Bu, MeCH(OH), H2N, AcNH] with O-mesitylenesulfonylhydroxylamine gave the corresponding 2-X- and 3-X-(1-amino)pyrazin-1-ium mesitylenesulfonates. 2-Alkylpyrazines (X = Me, Et, Pr, i-Pr) displayed a correlation between the logarithms of the concentration ratio of 2- and 3-substituted cations and substituent steric constants. Wider series of substituted pyrazines [X = H, Me, Et, Pr, i-Pr, MeCH(OH), H2N, AcNH] conformed to a multiparameter correlation between the logarithms of the concentration ratio of 2- and 3-substituted cations, on the one hand, and substituent constants σI, σRo, and E so, on the other. The obtained data on the regioselectivity of amination of pyrazines were interpreted in terms of DFT/PBE/3Z quantum-chemical calculations.  相似文献   

16.
The signals in the13C NMR spectra of 2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-dienes (R1=R2=H, Me,cyclo-C3H5, SiMe3, SnMe3, R1=Me, R2=H, Cl) were completely assigned using 2D NMR spectroscopy. The pattern of the variation of the chemical shifts in the13C NMR spectra indicates that the effects of substituents R1 and R2 on the heterocycle and on the phenyl groups are of inductive rather than mesomeric origin and include the direct through-space polarization of bonds (field effect). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1962–1965, November, 1997.  相似文献   

17.
Treatment of the thioether‐substituted secondary phosphanes R2PH(C6H4‐2‐SR1) [R2=(Me3Si)2CH, R1=Me ( 1PH ), iPr ( 2PH ), Ph ( 3PH ); R2=tBu, R1=Me ( 4PH ); R2=Ph, R1=Me ( 5PH )] with nBuLi yields the corresponding lithium phosphanides, which were isolated as their THF ( 1 – 5Pa ) and tmeda ( 1 – 5Pb ) adducts. Solid‐state structures were obtained for the adducts [R2P(C6H4‐2‐SR1)]Li(L)n [R2=(Me3Si)2CH, R1=nPr, (L)n=tmeda ( 2Pb ); R2=(Me3Si)2CH, R1=Ph, (L)n=tmeda ( 3Pb ); R2=Ph, R1=Me, (L)n=(THF)1.33 ( 5Pa ); R2=Ph, R1=Me, (L)n=([12]crown‐4)2 ( 5Pc )]. Treatment of 1PH with either PhCH2Na or PhCH2K yields the heavier alkali metal complexes [{(Me3Si)2CH}P(C6H4‐2‐SMe)]M(THF)n [M=Na ( 1Pd ), K ( 1Pe )]. With the exception of 2Pa and 2Pb , photolysis of these complexes with white light proceeds rapidly to give the thiolate species [R2P(R1)(C6H4‐2‐S)]M(L)n [M=Li, L=THF ( 1Sa , 3Sa – 5Sa ); M=Li, L=tmeda ( 1Sb , 3Sb – 5Sb ); M=Na, L=THF ( 1Sd ); M=K, L=THF ( 1Se )] as the sole products. The compounds 3Sa and 4Sa may be desolvated to give the cyclic oligomers [[{(Me3Si)2CH}P(Ph)(C6H4‐2‐S)]Li]6 (( 3S )6) and [[tBuP(Me)(C6H4‐2‐S)]Li]8 (( 4S )8), respectively. A mechanistic study reveals that the phosphanide–thiolate rearrangement proceeds by intramolecular nucleophilic attack of the phosphanide center at the carbon atom of the substituent at sulfur. For 2Pa / 2Pb , competing intramolecular β‐deprotonation of the n‐propyl substituent results in the elimination of propene and the formation of the phosphanide–thiolate dianion [{(Me3Si)2CH}P(C6H4‐2‐S)]2?.  相似文献   

18.
Alkane elimination reactions of the tethered bis(urea) proligand 1,4‐(tBuNHCONH)2‐C4H8 ( 1 ) with ZnR2 (R = Me, Et, nPr) yielded trimetallic zinc complexes [RZn‐1,4‐(tBuNHCON)2‐C4H8]2Zn [R = Me ( 2 ), Et ( 3 ), and nPr ( 4 )]. 2 – 4 were characterized by heteronuclear NMR (1H, 13C) and IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction.  相似文献   

19.
Electrochemical reduction of 1-X-1-R1-5-methyl-2-phenyl-7-R2-1,2-dihydro-1,2,4,3-tri-azaphospholo[4,5-a]quinolines1–5 (1: X is the lone electron pair (LEP), R1=Et2N, R2=Me;2: X=LEP, R1=Ph, R2=H;3: X=S, R1=Et2N, R2=H;4: X=LEP, R1=Et2N, R2=H;5: X=LEP, R1=MeO, R2=H) in DMF with 0.1M Bu4NI as supporting electrolyte is reversible and results in metastable radical anions. Radical anions of compounds1–3 efficiently reduce 1,2-dichloro-2-methoxycarbonyl-2-methylcyclopropane both in the presence and in absence of Ni11 ions. Effective reduction rate constants have been evaluated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 1999.  相似文献   

20.
A series of substituted pyrazino[2,3‐f][1,10]‐phenanthroline (Rppl) ligands (with R=Me, COOH, COOMe) were synthetized (see 1 – 4 in Scheme 1). The ligands can be visualized as formed by a bipyridine and a quinoxaline fragment (see A and B ). Homoleptic [Ru(R1ppl)3](PF6)2 and heteropleptic [Ru(R1ppl){(R2)2bpy}2](PF6)2 (R1=H, Me, COOMe and R2=H, Me) metal complexes 5 – 7 and 8 – 13 , respectively, based on these ligands were also synthesized and characterized by conventional techniques (Schemes 2 and 3, resp.). In the heteroleptic complexes, the R1‐ppl ligand reduces at a less‐negative potential than the bpy ligand, reflecting the acceptor property conferred by the quinoxaline moiety. The potentiality of some of these complexes as solar‐cell dyes is discussed.  相似文献   

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