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1.
Fumio Sanda Taizo Fujiyama Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(5):732-741
α‐Methyl glutamic acid (L ‐L )‐, (L ‐D )‐, (D ‐L )‐, and (D ‐D )‐γ‐dimers were synthesized from L ‐ and D ‐glutamic acids, and the obtained dimers were subjected to polycondensation with 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride and 1‐hydroxybenzotriazole hydrate as condensation reagents. Poly‐γ‐glutamic acid (γ‐PGA) methyl ester with the number‐average molecular weights of 5000∼20,000 were obtained by polycondensation in N,N‐dimethylformamide in 44∼91% yields. The polycondensation of (L ‐L )‐ and (D ‐D )‐dimers afforded the polymers with much larger |[α]D | compared with the corresponding dimers. The polymer could be transformed into γ‐PGA by alkaline hydrolysis or transesterification into α‐benzyl ester followed by hydrogenation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 732–741, 2001 相似文献
2.
Mattia Silvi Carlo Cassani Antonio Moran Paolo Melchiorre 《Helvetica chimica acta》2012,95(10):1985-2006
The direct and enantioselective γ‐alkylation of α‐substituted α,β‐unsaturated aldehydes proceeding under dienamine catalysis is described. We have found that the Seebach modification of the diphenyl‐prolinol silyl ether catalyst in combination with saccharin as an acidic additive promotes an SN1 alkylation pathway, while ensuring complete γ‐site selectivity and a high stereocontrol. Theoretical and spectroscopic investigations have provided insights into the conformational behavior of the covalent dienamine intermediate derived from the condensation of 2‐methylpent‐2‐enal and the chiral amine. Implications for the mechanism of stereoinduction are discussed. 相似文献
3.
H3PW12O40/SiO2 or (PW/SiO2) promotes the regio‐, stereo‐ and chemoselective Claisen‐Schmidt condensation with improved yields. 相似文献
4.
Zolfigol Mohammad Ali Khazaei Ardeshir Mokhlesi Mohammad Zare Abdolkarim Safaiee Maliheh Derakhshan‐Panah Fatemeh Keypour Hassan Ali Dehghani‐Firouzabadi Ahmad Merajoddin Maria 《中国化学》2012,30(2):345-352
Aluminum chloride (AlCl3) efficiently catalyzes one‐pot multicomponent condensation of enolizable ketones or alkyl acetoacetates with aldehydes, acetonitrile and acetyl chloride to afford β‐acetamido ketone or ester derivatives in high to excellent yields and in relatively short reaction times. Moreover, by this synthetic method, some novel β‐acetamido ketones and esters (i.e. one complex structure) are prepared. 相似文献
5.
We report a new, effective and simple method for preparing α,β‐unsaturated carbonyl compounds by reacting ketones and aromatic alcohols at 56°C in the presence of CrO3 (CrO3 acts as an oxidant and also a catalyst) for around 10 h. The condensation reactions occurred effectively among a wide combination of ketones and alcohols. The procedure is simple and the yields can be high up to 98%. And a probable mechanism is proposed. 相似文献
6.
A new β‐ketoimine ligand was prepared through traditional condensation of 2‐acetylcyclohexanone with 1‐naphthylamine. Consequently, the new moisture‐ and air‐stable bis(β‐ketoamino)nickel(II) complex Ni[2‐CH3C(O)C6H8(NAr)]2 (Ar = naphthyl) was synthesized and characterized. The solid‐state structures of the ligand and complex have been determined by single‐crystal X‐ray diffraction. Additionally, the new complex is a highly active catalyst precursor for polymerization of norbornene in combination with methylaluminoxane. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
7.
Synthesis of Phenanthrene Derivatives through the Reaction of an α,α‐Dicyanoolefin with α,β‐Unsaturated Carbonyl Compounds 下载免费PDF全文
Abdolali Alizadeh Seyed Yasub Hosseini Hadi Sedighian Fahimeh Bayat 《Helvetica chimica acta》2015,98(10):1426-1434
Phenanthrene derivatives were prepared by reacting an α,α‐dicyanoolefin with different α,β‐unsaturated carbonyl compounds resulting from Wittig reaction of ninhydrin and phosphanylidene or condensation of barbituric acid and an aldehyde. The easy procedure, mild and metal‐catalyst free, reaction conditions, good yields, and no need for chromatographic purifications are important features of this protocol. The structures of the product of type 3 and 5 were corroborated spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS). A plausible mechanism for this type of reaction is proposed (Scheme 1). 相似文献
8.
Highly dispersed palladium nanoclusters incorporated in amino‐functionalized silica spheres for the selective hydrogenation of succinic acid to γ‐butyrolactone 下载免费PDF全文
Highly dispersed palladium nanoclusters incorporated on amino‐functionalized silica sphere surfaces (Pd/SiO2‐NH2) were fabricated by a simple one‐pot synthesis utilizing 3‐(2‐aminoethylamino)propyltrimethoxysilane (AAPTS) as coordinating agent. Uniform palladium nanoclusters with an average size of 1.1 nm can be obtained during the co‐condensation of tetraethyl orthosilicate and AAPTS owing to the strong interaction between palladium species and amino groups in AAPTS. The palladium particle size can be controlled by addition of AAPTS and plays a significant role in the catalytic performance. The Pd/SiO2‐NH2 catalyst exhibits high catalytic activity for succinic acid hydrogenation with 100% conversion and 94% selectivity towards γ‐butyrolactone using 1,4‐dioxane as solvent at 240°C and 60 bar for 4 h. Moreover, the Pd/SiO2‐NH2 catalyst is robust and readily reusable without loss of its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
9.
A simple and convenient procedure for the synthesis of 14‐aryl or alkyl‐14H‐dibenzo[a. j]xanthene derivatives is described through a one‐pot condensation of β‐naphthol with various aryl or alkyl aldehydes in the presence of HBF4‐SiO2 as the catalyst under thermal and solvent‐free conditions. 相似文献
10.
A Ph3P‐catalyzed cyclization of α‐halogeno ketones 2 with dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates) 3 produced halogenated α,β‐unsaturated γ‐butyrolactone derivatives 4 in good yields (Scheme 1, Table). The presence of electron‐withdrawing groups such as halogen atoms at the α‐position of the ketones was necessary in this reaction. Cyclization of α‐chloro ketones resulted in higher yields than that of the corresponding α‐bromo ketones. Dihalogeno ketones similarly afforded the expected γ‐butyrolactone derivatives in high yields. 相似文献
11.
Magnetically separable g‐C3N4 hybrid nanocomposite: Highly efficient and eco‐friendly recyclable catalyst for one‐pot synthesis of α‐aminonitriles 下载免费PDF全文
A magnetically separable graphitic carbon nitride nanocomposite (Fe3O4/g‐C3N4) as a catalyst for the three‐component condensation reactions of carbonyl compounds, amines and trimethylsilylcyanide was thoroughly investigated. The reaction of these three components was found to be efficient, economical and green and took place in the presence of a catalytic amount of the magnetically separable catalyst to yield the corresponding α‐aminonitriles in good to excellent yields. The prepared nanocomposite was characterized using scanning electron microscopy and energy‐dispersive X‐ray and Fourier transform infrared spectroscopies. The nanocomposite was also found to be reusable could be recovered easily and reused several times without distinct deterioration in its catalytic activity. 相似文献
12.
Cu(II) immobilized on guanidinated epibromohydrin‐functionalized γ‐Fe2O3@TiO2 (γ‐Fe2O3@TiO2‐EG‐Cu(II)): A highly efficient magnetically separable heterogeneous nanocatalyst for one‐pot synthesis of highly substituted imidazoles 下载免费PDF全文
A simple, efficient and eco‐friendly procedure has been developed using Cu(II) immobilized on guanidinated epibromohydrin‐functionalized γ‐Fe2O3@TiO2 (γ‐Fe2O3@TiO2‐EG‐Cu(II)) for the synthesis of 2,4,5‐trisubstituted and 1,2,4,5‐tetrasubstituted imidazoles, via the condensation reactions of various aldehydes with benzil and ammonium acetate or ammonium acetate and amines, under solvent‐free conditions. High‐resolution transmission electron microscopy analysis of this catalyst clearly affirmed the formation of a γ‐Fe2O3 core and a TiO2 shell, with mean sizes of about 10–20 and 5–10 nm, respectively. These data were in very good agreement with X‐ray crystallographic measurements (13 and 7 nm). Moreover, magnetization measurements revealed that both γ‐Fe2O3@TiO2 and γ‐Fe2O3@TiO2‐EG‐Cu(II) had superparamagnetic behaviour with saturation magnetization of 23.79 and 22.12 emu g?1, respectively. γ‐Fe2O3@TiO2‐EG‐Cu(II) was found to be a green and highly efficient nanocatalyst, which could be easily handled, recovered and reused several times without significant loss of its activity. The scope of the presented methodology is quite broad; a variety of aldehydes as well as amines have been shown to be viable substrates. A mechanism for the cyclocondensation reaction has also been proposed. 相似文献
13.
A simple and eco‐friendly method for the preparation of 1,5‐diaryl‐3‐(arylamino)‐1H‐pyrrol‐2(5H)‐ones via the cyclo‐condensation reaction of aldehydes, amines and ethyl pyruvate in the presence of silica supported ferric chloride (SiO2‐FeCl3) as reusable heterogeneous catalyst is described. The present methodology offers several advantages such as excellent yields, simple procedure and short reaction times. 相似文献
14.
Isao Yamaguchi Kohtaro Osakada Takakazu Yamamoto 《Journal of polymer science. Part A, Polymer chemistry》1999,37(9):1383-1392
The reactions of 3,3′‐diaminobenzidine with 1,12‐dodecanediol in 1 : 1–1:3 molar ratios in the presence of RuCl2(PPh3)3 catalyst give poly(alkylenebenzimidazole), [ (CH2)11 O (CH2)11 Im / (CH2)10 Im ]n (Im: 5,5′‐dibenzimidazole‐2,2′‐diyl) (Ia‐Id) in 71–92% yields. The relative ratio between the [(CH2)11 O (CH2)11 Im ] unit (A) and the [‐ (CH2)10 Im ] unit (B) in the polymer chain varies depending on the ratio of the substrates used. The polymer Ia obtained from the 1 : 3 reaction contains these structural units in a 98 : 2 ratio. The polymers are soluble in polar solvents such as DMF (N,N‐dimethylformamide), DMSO (dimethyl sulfoxide), and NMP (N‐methyl‐2‐pyrrolidone) and have molecular weights Mn (Mw) of 4,200–4,800 (4,800–6,500) by GPC (polystyrene standard). The polymerization of the diol and 3,3′‐diaminobenzidine in higher molar ratios leads to partial cross‐linking of the resulting polymers Ie and If via condensation of imidazole NH group with CH2OH group. Similar reactions of 3,3′‐diaminobenzidine with α,ω‐diols, HO(CH2)mOH (m = 4–10), in a 1 : 3 molar ratio give the polymers containing [ (CH2)m−1 O (CH2) m−1 Im ] and [ (CH2) m−2 Im ] units with partial cross‐linked structures. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1383–1392, 1999 相似文献
15.
The previously described chiral 2‐acyloxathianes 5 (Scheme I) are used in two different enantioselective syntheses of γ‐butyrolactones. In one synthesis, Grignard addition, cleavage and reduction to carbinols RR'C(OH)CH2OH is followed by tosylation, malonate homologation, lactonization, and removal of the carbomethoxy group to give optically active γ‐lactones. A modification of this synthesis (Scheme I) leads to optically active α‐methylene‐γ‐lactones. In the second synthesis, reaction of a bromomagnesium enolate with ketones 5 leads to β‐hydroxyesters, which, by appropriate sequences of reduction and cleavage (Scheme II) are converted to optically active α‐ or β‐hydroxy‐γ‐lactones. 相似文献
16.
Synthesis and Characterization of β‐Diketiminate Aluminum Compounds and Their Use in the Ring‐Opening Polymerization of ε‐Caprolactone 下载免费PDF全文
Xiaoli Ma Miaomiao Yao Mingdong Zhong Ziyan Deng Wenling Li Zhi Yang Herbert W. Roesky 《无机化学与普通化学杂志》2017,643(2):198-202
Four aluminum alkyl compounds, [CH{(CH3)CN‐2,4,6‐MeC6H2}2AlMe2] ( 1 ), [CH{(CH3)CN‐2,4,6‐MeC6H2}2AlEt2] ( 2 ), [CH{(CH3)CN‐2‐iPrC6H4}2AlMe2] ( 3 ), and [CH{(CH3)CN‐2‐iPrC6H4}2AlEt2] ( 4 ), bearing β‐diketiminate ligands [CH{(Me)CN‐2,4,6‐MeC6H2}]2 (L1H) and [CH{(Me)CN‐2‐iPrC6H4}]2 (L2H) were obtained from the reactions of trimethylaluminum, triethylaluminum with the corresponding β‐diketiminate, respectively. All compounds were characterized by 1H NMR and 13C NMR spectroscopy, single‐crystal X‐ray structural analysis, and elemental analysis. Compounds 1 – 4 were found to catalyze the ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) with good activity. 相似文献
17.
18.
Synthesis and X‐ray Crystal Structures of Zinc Dichloride Complexes Supported by a β‐Diimine Ligand 下载免费PDF全文
Christoph Scheiper Dominik Naglav Dieter Bläser Christoph Wölper Stephan Schulz 《无机化学与普通化学杂志》2015,641(5):871-875
β‐Diimine zinc dichloride complexes [CH2{C(Me)NAr}2]ZnCl2 [Ar = Mes ( 1 ), Dipp ( 2 )] were obtained from the reactions of ZnCl2 with the corresponding β‐iminoamines [ArN(H)C(Me)CHC(Me)NAr]. Complexes 1 and 2 were characterized by multinuclear NMR (1H, 13C) and IR spectroscopy, elemental analyses as well as by single‐crystal X‐ray diffraction. The energy differences between the enamine‐imine tautomers of the β‐iminoamines were quantified by quantum chemical calculations. 相似文献
19.
A convenient synthesis of α,α′‐ homo‐ and α,α′‐hetero‐bifunctionalized poly(ε‐caprolactone)s by ring opening polymerization: The potentially valuable precursors for miktoarm star copolymers 下载免费PDF全文
Sachin S. Patil Bhausaheb V. Tawade Prakash P. Wadgaonkar 《Journal of polymer science. Part A, Polymer chemistry》2016,54(6):844-860
Two new ring opening polymerization (ROP) initiators, namely, (3‐allyl‐2‐(allyloxy)phenyl)methanol and (3‐allyl‐2‐(prop‐2‐yn‐1‐yloxy)phenyl)methanol each containing two reactive functionalities viz. allyl, allyloxy and allyl, propargyloxy, respectively, were synthesized from 3‐allylsalicyaldehyde as a starting material. Well defined α‐allyl, α′‐allyloxy and α‐allyl, α′‐propargyloxy bifunctionalized poly(ε‐caprolactone)s with molecular weights in the range 4200–9500 and 3600–10,900 g/mol and molecular weight distributions in the range 1.16–1.18 and 1.15–1.16, respectively, were synthesized by ROP of ε‐caprolactone employing these initiators. The presence of α‐allyl, α′‐allyloxy and α‐allyl, α′‐propargyloxy functionalities on poly(ε‐caprolactone)s was confirmed by FT‐IR, 1H, 13C NMR spectroscopy, and MALDI‐TOF analysis. The kinetic study of ROP of ε‐caprolactone with both the initiators revealed the pseudo first order kinetics with respect to ε‐caprolactone consumption and controlled behavior of polymerization reactions. The usefulness of α‐allyl, α′‐allyloxy functionalities on poly(ε‐caprolactone) was demonstrated by performing the thiol‐ene reaction with poly(ethylene glycol) thiol to obtain (mPEG)2‐PCL miktoarm star copolymer. α‐Allyl, α′‐propargyloxy functionalities on poly(ε‐caprolactone) were utilized in orthogonal reactions i.e copper catalyzed alkyne‐azide click (CuAAC) with azido functionalized poly(N‐isopropylacrylamide) followed by thiol‐ene reaction with poly(ethylene glycol) thiol to synthesize PCL‐PNIPAAm‐mPEG miktoarm star terpolymer. The preliminary characterization of A2B and ABC miktoarm star copolymers was carried out by 1H NMR spectroscopy and gel permeation chromatography (GPC). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 844–860 相似文献
20.
Hans R. Kricheldorf Heiko Hachmann‐Thiessen Gert Schwarz 《Journal of polymer science. Part A, Polymer chemistry》2005,43(16):3667-3674
Monofunctional polylactones were prepared by Bu2Sn(OMe)2‐initiated ring‐opening polymerization of ε‐caprolactone (εCL) followed by acylation with bromoacetylbromide. Telechelic polylactones and polylactides were prepared via ring‐expansion polymerization with 2,2‐dibutyl‐2‐stanna‐1,3‐dioxepane (DSDOP) or 2,2‐dibutyl‐2‐stanna‐pentaoxacyclotridecane (Bu2SnTEG) as cyclic initiator. In situ combination of the polymerization with condensation by means of bromoacetylbromide yielded polylactones having bromoacetate endgroups. These endgroups were subjected to nucleophilic substitution with 3‐mercaptopropyl trimethoxysilane (3‐MPTMS). Analogous experiments were conducted with dl‐lactide. The telechelic trimethoxysilyl‐endcapped polylactones were characterized by viscosity, 1H and 13C NMR‐spectroscopy, and MALDI‐TOF mass spectrometry. The mass spectra revealed small amounts of cyclic oligolactones as byproducts in all samples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3667–3674, 2005 相似文献