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1.
The unique reactive intermediate formed in the 3,4,6‐tri‐O‐benzyl‐d‐glucal–TfOH (triflic acid)–n‐Bu4NI reaction system (in dichloromethane) reacted with nucleophiles in a regio‐ and stereoselective manner. These selectivities resulted in hitherto unknown compounds, such as benzyl 4,6‐di‐O‐benzyl‐2,3‐dideoxy‐3‐iodo‐α‐glucopyranoside, which was obtained in the presence of an iodide ion as a nucleophile. The corresponding 2‐deoxy α‐glycosides were obtained exclusively in the corresponding reaction with hydroxylic nucleophiles.  相似文献   

2.
Quite unlike the reported facile ene reactions on the periphery of many related heterocyclic systems, similarly disposed moieties on the periphery of the chromen‐4‐one (=4H‐1‐benzopyran‐4‐one) system fail to undergo an ene reaction and display a rather unusual preference for an overall [1,5] shift of the allylic C‐atom. Thus, heating xylene solutions of 2‐(N‐allylanilino)‐, 2‐(N‐crotylanilino)‐, and 2‐(N‐cinnamylamino)‐substituted (E)‐(oxochromenyl)propenoates 9a – c and 2‐[allyl(benzyl)amino]‐, 2‐[benzyl(crotyl)amino]‐, and 2‐[benzyl(cinnamyl)amino]‐substituted (E)‐(oxochromenyl)propenoates 16a – c in a sealed tube at 220–230° leads to a [1,5] shift of the allylic moieties (allyl, crotyl, cinnamyl), which is followed by intramolecular cyclization involving the N‐atom and the ester function, to give the 3‐allyl‐3‐crotyl‐, and 3‐cinnamyl‐substituted‐1‐phenyl‐ or 1‐benzyl‐2H‐[1]benzopyrano[2,3‐b]pyridine‐2,5(1H)‐diones 10a – c and 17a – c . The anticipated carbonyl–ene reaction in the 2‐(N‐allylanilino)‐, 2‐(N‐crotylanilino)‐, 2‐(N‐cinnamylanilino)‐, 2‐[allyl(benzyl)amino]‐, 2‐[benzyl(crotyl)amino]‐, and 2‐[benzyl(cinnamyl)amino]‐substituted 4‐oxochromene‐3‐carboxaldehydes 8a – c and 15a – c is also not observed, and these molecules remain untransformed under identical conditions. No [1,5] shifts of benzyl, phenyl, or methyl groups are observed, even in the absence of allylic moieties, though facile [1,5]‐H shift occurs in 2‐(benzylamino)‐ and 2‐(phenylamino)‐substituted (E)‐(oxochromenyl)propenoates 23a , b , which is followed by a similar intramolecular cyclization leading to the 2H‐[1]benzopyrano[2,3‐b]pyridine‐2,5(1H)‐diones 24a , b .  相似文献   

3.
3‐Benzylindole‐2‐carbohydrazides (4) on reaction with triethylorthoformate in a polar solvent like DMF yielded only 10‐benzyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles (5) while (4) on reaction with triethylorthoacetate in DMF yielded both 10‐benzyl‐4‐methyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles (5) and 3‐benzyl‐2‐(5‐methyl‐1,3,4‐oxadiazol‐2‐yl)indoles (6) instead of only the triazinoindoles as expected. The oxadiazolylindoles (6) were also synthesized by refluxing (4) with excess of orthoesters. The structures of the compounds formed were characterized by their analytical and spectral data.  相似文献   

4.
Silica-supported polyphosphoric acid (PPA-SiO2) was found to be an efficient catalyst for the multi-component condensation reaction of benzaldehydes, 2-naphthol, and methyl/benzyl carbamate to afford the corresponding N-[α-(β-hydroxy-α-naphthyl)(benzyl)] O-alkyl carbamate derivatives in good to excellent yields. This new approach consistently has the advantage of short reaction time, high conversions, clean reaction profiles, and simple experimental and work-up procedures.  相似文献   

5.
The synthesis of α‐benzamido‐α‐benzyl lactones 23 of various ring size was achieved either via ‘direct amide cyclization’ by treatment of 2‐benzamido‐2‐benzyl‐ω‐hydroxy‐N,N‐dimethylalkanamides 21 in toluene at 90 – 110° with HCl gas or by ‘ring transformation’ of 4‐benzyl‐4‐(ω‐hydroxyalkyl)‐2‐phenyl‐1,3‐oxazol‐5(4H)‐ones under the same conditions. The precursors were obtained by C‐alkylations of 4‐benzyl‐2‐phenyl‐1,3‐oxazol‐5(4H)‐one ( 15 ) with THP‐ or TBDMS‐protected ω‐hydroxyalkyl iodides. Ring opening of the THP‐protected oxazolones by treatment with Me2NH followed by deprotection of the OH group gave the diamides 21 , whereas deprotection of the TBDMS series of oxazolones 25 with TBAF followed by treatment with HCl gas led to the corresponding lactones 23 in a one‐pot reaction.  相似文献   

6.
The present study investigates the challenging approach of post‐polymerization modification on polymers with a sterically demanding reaction center. Therefore, the general possibility to functionalize polymethylene moieties was investigated. Poly(benzyl 2‐ylidene‐acetate) was synthesized by polymerization of benzyl 2‐diazoacetate utilizing [(L‐prolinate)RhI(1,5‐dimethyl‐1,5‐cyclooctadiene)] as a catalyst. Subsequently, the modification of C1 polymerized poly(benzyl 2‐ylidene‐acetate) with amines was analyzed and the obtained data set was compared with experimental data derived for the C2 analog poly(benzyl acrylate). This is the first study on post‐polymerization modification utilizing densely functionalized polymethylenes as starting materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 686–691  相似文献   

7.
5‐Alkyl‐4‐benzyl‐1,3‐dihydroimidazol‐2‐ones ( 3a‐d ) and 5‐alkyl‐4‐benzyl‐1,3‐dihydroimidazole‐2‐thiones (7a‐d) were prepared via Dakin West reaction on DL‐phenylalanine with the appropriate aliphatic acid anhydrides followed by hydrolysis and reaction with potassium cyanate or potassium thiocyanate. Compounds 3a‐d were alkylated with ethoxymethyl chloride to give the alkylated imidazoles 5a‐d which were considered analogues of Emivirine with deletion of carbonyl group at the 4‐position. Alkylation of 7a‐d afforded the corresponding S‐alkylated derivatives 8a‐p which in a similar way were considered analogues of S‐DABO. However all the imidazole derivatives were devoid of activity against HIV.  相似文献   

8.
《中国化学》2017,35(7):1141-1148
Synthesis of di‐substituted aryl olefins via a Pd(0)‐catalyzed cross‐coupling reaction of biphenyl ketones/aldehydes, tosylhydrazide, and aryl bromides (or benzyl halides) was developed. This methodology was achieved by one‐pot two‐step reactions involving the preparation of N ‐tosylhydrazones by reacting tosylhydrazide with biphenyl ketones/aldehydes, followed by coupling with aryl bromides (or benzyl halides) in the presence of Pd(PPh3 )4 and lithium t ‐butoxide to produce various di‐substituted aryl olefins in moderate to good yields.  相似文献   

9.
An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.  相似文献   

10.
Abstract

Glucuronic acid‐containing di‐ and trisaccharide thioglycoside building blocks, ethyl (benzyl 2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranosyluronate)‐(1 → 2)‐3‐O‐allyl‐4,6‐di‐O‐benzyl‐1‐thio‐α‐D‐mannopyranoside, ethyl (benzyl 2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranosyluronate)‐(1 → 2)‐6‐O‐acetyl‐3‐O‐allyl‐4‐O‐benzyl‐1‐thio‐α‐D‐mannopyranoside and ethyl (2,3,4‐tri‐O‐benzyl‐β‐D‐xylopyranosyl)‐(1 → 4)‐[(benzyl 2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranosyluronate)‐(1 → 2)]‐3‐O‐allyl‐6‐O‐benzyl‐1‐thio‐α‐D‐mannopyranoside, corresponding to repetitive structures in the capsular polysaccharide (CPS) of Cryptococcus neoformans, have been synthesized. The blocks contain an orthogonal allyl group in the 3‐position of the mannose residue to allow formation of the (1 → 3)‐linked mannan backbone of the CPS and benzyl ethers as persistent protecting groups to facilitate access to acetylated target structures. The glucuronic acid moiety was introduced using an acetylated trichloroacetimidate donor and the xylose residue employing the benzoylated bromo sugar to ensure β‐selectivity in the couplings. Exchange to benzyl protecting groups was then performed at the di‐ or trisaccharide level. Assembly of suitable blocks employing DMTST as promoter in diethyl ether then afforded, in high yield and with stereoselectivity, a protected pentasaccharide corresponding to a C. neoformans serotype D CPS structure.  相似文献   

11.
The synthesis of arborescent polymers with poly(γ‐benzyl L‐glutamate) (PBG) side chains was achieved through successive grafting reactions. The linear PBG building blocks were produced by the ring‐opening polymerization of γ‐benzyl L‐glutamic acid N‐carboxyanhydride initiated with n‐hexylamine. The polymerization conditions were optimized to minimize the loss of amino chain termini in the reaction. Acidolysis of a fraction of the benzyl groups on a linear PBG substrate and coupling with linear PBG using a carbodiimide/hydroxybenzotriazole promoter system yielded a comb‐branched or generation zero (G0) arborescent PBG. Further partial deprotection and grafting cycles led to arborescent PBG of generations G1 to G3. The solvent used in the coupling reaction had a dramatic influence on the yield of graft polymers of generations G1 and above, dimethylsulfoxide being preferable to N,N‐dimethylformamide. This grafting onto scheme yielded well‐defined (Mw/Mn ≤ 1.06), high molecular weight arborescent PBG in a few reaction cycles, with number‐average molecular weights and branching functionalities reaching over 106 and 290, respectively, for the G3 polymer. α‐Helix to coiled conformation transitions were observed from N,N‐dimethylformamide to dimethyl sulfoxide solutions, even for the highly branched polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5270–5279  相似文献   

12.
The present investigation introduces a new series of cycloplatinated(II) complexes, with the general formula Pt(O‐bpy)(Me)(CN‐R)] (R = benzyl, 2‐naphtyl and tert‐butyl), which are able to generate the stable trans‐Pt(IV) product in the solution after the reaction with iodomethane. In fact, the trans product is both the kinetic and thermodynamic product of the reaction; this observation was supported by DFT calculations. These Pt(II) complexes are supported by 2,2'‐bipyridine N‐oxide (O‐bpy) and one of several isocyanides as the cyclometalated and ancillary ligands, respectively. These new Pt(II) complexes undergo oxidative addition with MeI to give the corresponding trans‐Pt(IV) complexes. All the complexes were identified employing the multi‐nuclear NMR spectroscopy and single crystal X‐ray crystallography. The kinetic investigations were also performed for the oxidative addition reactions in order to measure the reaction rates; the reaction was followed by UV‐Vis spectroscopy. The rates obtained follow the trend CN‐tBu > CN‐Bz > CN‐2 Np for the CN‐R ligands in the Pt(II) complexes. The order can be related to the degree of electron‐donation of the R group (tert‐butyl > benzyl > 2‐naphtyl).  相似文献   

13.
A series of novel four‐arm A2B2 and A2BC and five‐arm A2B2C miktoarm star polymers, where A is poly(dimethylsiloxane) (PDMS), B is polystyrene (PS), and C is polyisoprene (PI), were successfully synthesized by the combination of chlorosilane and benzyl chloride linking chemistry. This new and general methodology is based on the linking reaction of in‐chain benzyl chloride functionalized poly(dimethylsiloxane) (icBnCl–PDMS) with the in‐chain diphenylalkyl (icD) living centers of PS‐DLi‐PS, PS‐DLi‐PI, or (PS)2‐DLi‐PI. icBnCl–PDMS was synthesized by the selective reaction of lithium PDMS enolate (PDMSOLi) with the chlorosilane groups of dichloro[2‐(chloromethylphenyl)ethyl]methylsilane, leaving the benzyl chloride group intact. The icD living polymers, characterized by the low basicity of DLi to avoid side reactions with PDMS, were prepared by the reaction of the corresponding living chains with the appropriate chloro/bromo derivatives of diphenylethylene, followed by a reaction with BuLi or the living polymer. The combined molecular characterization results of size exclusion chromatography, 1H NMR, and right‐angle laser light scattering revealed a high degree of structural and compositional homogeneity in all miktoarm stars prepared. The power of this general approach was demonstrated by the synthesis of a morphologically interesting complex miktoarm star polymer composed of two triblock terpolymer (PS‐b‐PI‐b‐PDMS) and two diblock copolymer (PS‐b‐PI) arms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6587–6599, 2006  相似文献   

14.
From the reaction of 1H‐imidazole ( 1a ), 4,5‐dichloro‐1H‐imidazole ( 1b ), 1H‐benzimidazole ( 1c ), 1‐methyl‐1H‐imidazole ( 1d ), and 1‐methyl‐1H‐benzimidazole ( 1f ) with methyl 4‐(bromomethyl)benzoate ( 2 ), symmetrically and nonsymmetrically 4‐(methoxycarbonyl)benzyl‐substituted N‐heterocyclic carbene (NHC) precursors, 3a – 3f , were synthesized. These NHC precursors were then reacted with silver(I) acetate (AgOAc) to yield the NHC–silver acetate complexes (acetato‐κO){1,3‐bis[4‐(methoxycarbonyl)benzyl]imidazol‐2‐ylidene}silver ( 4a ), (acetato‐κO){4,5‐dichloro‐1,3‐bis[4‐(methoxycarbonyl)benzyl]‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4b ), (acetato‐κO){1,3‐bis[4‐(methoxycarbonyl)benzyl]‐2,3‐dihydro‐1H‐benzimidazol‐2‐yl}silver ( 4c ), (acetato‐κO){1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4d ), (acetato‐κO){4,5‐dichloro‐1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4e ), and (acetato‐κO){1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐benzimidazol‐2‐yl}silver ( 4f ), respectively. The three NHC–AgOAc complexes 4a, 4c , and 4d were characterized by single‐crystal X‐ray diffraction. All compounds studied in this work were preliminarily screened for their antimicrobial activities in vitro against Gram‐positive bacteria Staphylococcus aureus, and Gram‐negative bacteria Escherichia coli using the qualitative disk‐diffusion method. All NHC–AgOAc complexes exhibited weak‐to‐medium antibacterial activity with areas of clearance ranging from 4 to 7 mm at the highest amount used, while the NHC precursors showed significantly lower activity. In addition, NHC–AgOAc complexes 4a and 4b , and 4d – 4f exhibited in preliminary cytotoxicity tests on the human renal‐cancer cell line Caki‐1 medium‐to‐high cytotoxicities with IC50 values ranging from 3.3±0.4 to 68.3±1 μM .  相似文献   

15.
A basic alumina‐supported microwave assisted simple methodology has been developed for the synthesis of aryl‐heteroaryl methanes (benzylated quinolones) via transition metal catalyzed cross‐coupling reaction of halo substituted polynuclear oxa‐aza quinolones with benzyl indium, an organometallic reagent easily derived from commercially available benzyl bromide.  相似文献   

16.
Novel phosphates, Op‐(hydroxymethyl)benzyl O,O‐diethyl phosphate ( 1 ) and O‐(2‐bromoisobutyryloxymethyl)benzyl O,O‐diethyl phosphate ( 2 ) were synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol and the successive reaction with 2‐bromoisobutyryl bromide in the presence of triethylamine and submitted to the polymerization of ?‐caprolactone and methyl methacrylate as the initiators. They afforded phosphate end‐functional poly(?‐caprolactone) and poly(methyl methacrylate) with controlled molecular weights and polydispersity ratios by living ring‐opening polymerization and samarium‐induced polymerization. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate end‐functional polymers as the latent polymeric initiators in the presence of ZnCl2. The polymerization of GPE did not proceed below 90 °C, but it rapidly proceeded to afford poly(GPE) above the temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3832–3840, 2001  相似文献   

17.
A series of new benzimidazolium chlorides bearing N,N′‐benzyl, 2,4,6‐trimethylbenzyl and 2,4,6‐triisopropylbenzyl substituents have been designed and synthesized from various o‐phenylenediamines. Subsequently, corresponding Cu‐based N‐heterocyclic carbenes (NHCs) were generated in situ in the reaction medium which represents a new application of NHCs exploiting distinct catalytic property towards intermolecular cyclization reaction cascade for the synthesis of 2‐aryl‐3‐(arylethynyl)quinoxalines from o‐phenylenediamines and terminal alkynes. The outcome of the cyclization reaction product depends upon the N,N′‐substituents present on the benzimidazolium chlorides.  相似文献   

18.
Radical catalyzed thiol‐ene reaction has become a useful alternative to the Huisgen‐type click reaction as it helps to expand the variability in reaction conditions as well as the range of clickable entities. Thus, direct generation of hyperbranched polymers bearing peripheral allyl groups that could be clicked using a variety of functional thiols would be of immense value. A specifically designed AB2 type monomer, that carries two allyl benzyl ethers groups and one alcohol functionality, was shown to undergo self‐condensation under acid‐catalyzed melt‐transetherification to yield a hyperbranched polyether that carries numerous allyl end‐groups. Importantly, it was shown that the kinetics of polymerization is not dramatically affected by the change of the ether unit from previously studied methyl benzyl ether to an allyl benzyl ether. The peripheral allyl groups were readily clicked quantitatively, using a variety of thiols, to generate an hydrocarbon‐soluble octadecyl‐derivative, amphiphilic systems using 2‐mercaptoethanol and chiral amino acid (N‐benzoyl cystine) derivatized hyperbranched structures; thus demonstrating the versatility of this novel class of clickable hyperscaffolds. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

19.
A reaction of N‐benzylpyridinamines with n‐BuLi, followed by a reaction with CS2 and R3SnCl or R2SnCl2 (R = n‐Bu, PhCH2, or Ph) gave a series of mononuclear organotin dithiocarbamates. A similar reaction of N,N'‐bis(benzyl)‐1,3‐benzenediamine and N,N'‐bis(benzyl)‐2,6‐pyridinediamine afforded dinuclear and macrocyclic organotin dithiocarbamates. All of these complexes were characterized by elemental analysis, IR, and multinuclear NMR (1H, 13C, and 119Sn). Their structures have been confirmed by the X‐ray single crystal diffraction analysis, suggesting the dithiocarbamate groups acted as anisobidentate chelating ligands in these complexes. The primary fungicidal activity of these complexes was tested in vitro, showing that most complexes displayed good antifungal activity to Sclerotinia sclerotiorum.  相似文献   

20.
A series of novel N‐((l‐benzyl‐lH‐l,2,3‐triazol‐5‐yl) methyl)‐4‐(6‐methoxy benzo[d ]thiazol‐2‐yl)‐2‐nitrobenzamide derivatives were prepared from 4‐(6‐methoxybenzo[d ]thiazol‐2‐yl)‐2‐nitro‐N‐(prop‐2‐ynyl) benzamide with benzyl azides by using click reaction (copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction) in the presence of CuSO4.5H2O and sodium ascaorbate. All the newly synthesized compounds were evaluated further in vitro antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus and Bacillus subtillis ), Gram‐negative bacteria (Echerichia coli and Pseudomonas aeuroginosa ), and fungi (Aspergillus niger and Aspergillusfumigatus ) strains. The new compounds were characterized based on spectroscopic evidence. Among them compounds 10a , 10h , and 10i were showed promising activity when compared with standard drugs Ciprofloxacin and Miconazole.  相似文献   

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