4,5-Dihydro-3H-naphtho[1,8-bc]furans 4 and 6 which have various substituents (R1 and R2) have been synthesized from 8-oxo-5,6,7,8-tetrahydro-1-naphthyloxyacetic acids 1 and 3 or their ethyl esters 2 . The reaction of acids 1 and 3 with sodium acetate in acetic anhydride gave a mixture of furans 4 and 6 and lactones 5 and 7 . The ratios of the products were varied according to the types of substituents (R1 and R2) in acids 1 and 3 . As the substituent R1 (R2 = hydrogen) in acids 1 was changed from hydrogen to a methyl, ethyl or isopropyl group, production of furans 4 became more difficult. However, when a phenyl group was used as the substituent, furan 4 was obtained in good yield. Similarly, as the substituent R2 (R1 = hydrogen) in acids 1 was changed from hydrogen to a methyl, ethyl or isopropyl group, furan formation was more difficult. In contrast, acids 3 which had electron-withdrawing substituents such as chlorine, bromine or a nitro group at the 4-position afforded furans 6 in good yield. 4,5-Dihydro-3H-naphtho[1,8-bc]furans 4 and 4,5-dihydro-3H-naphtho[1,8-bc]furan-2-carbocylic acids 8 were synthesized from the reaction of esters 2 and potassium hydroxide in dioxane. When the substituents R1 or R2 in esters 2 were varied from hydrogen to a methyl, ethyl or isopropyl group the total yields of furans 4 and furancarboxylic acids 8 were reduced. 相似文献
New chiral pyrazoles, (4R,7R)‐4‐methyl‐7‐isopropyl‐3‐phenyl‐ (3‐phenyliso menthopyrazole cis‐1), (4R,7S)‐4‐methyl‐7‐isopropyl‐ (1‐menthopyrazole; trans‐2), (4R,7R)‐4‐isopropyl‐7‐methyl‐ (iso carvomen‐thopyrazole, cis‐3) and (4R,7S)‐4‐isopropyl‐7‐methyl‐4,5,6,7‐tetrahydro‐1H‐indazole (carvomenthopyra‐zole, trans‐3) were prepared. The diastereomeric pairs of these 1–3 were structurally characterized by NMR spectroscopy. The subtle differences of structures of 1–3 should induce the useful effects for a chiral auxiliary or a chiral catalyst. 相似文献
Synthesis, spectral analysis, and antibacterial activity of new coumarin derivatives are described in this paper. Twelve new coumarin derivatives were synthesized in moderate to good yields by the react with 4‐methyl‐6‐(prop‐2‐ynyloxy)‐2H‐chromen‐2‐one ( 3a – c ) and ethyl azide ( 4a – l ) and done by the click reaction to obtained 6‐[(l‐ethyl‐lH‐l,2,3‐triazol‐4‐yl)methoxy]‐4‐methyl‐2H‐chromen‐2‐ones ( 5a – l ). The structures of all the newly synthesized molecules were assigned by elemental analysis and spectral data. The synthesized compounds were screened for their antibacterial activities strains using Cup plate method. 相似文献
Abstract The synthesis of various substituted 1,4‐dihydropyridines has been achieved by the reaction of aldehydes, ethyl/methyl acetoacetates, and ammonium acetate in water using phase‐transfer catalyst under microwave irradiation. Compared to the classical Hantzsch's reaction conditions, this new method consistently has the advantage of good yields and short reaction times. Bifunctional compounds containing two units have been synthesized using dialdehyde as precursor in good yields. 相似文献
2H‐Pyridazino[1,2‐a]indazole‐1,6,9(11H)‐triones were synthesized through one‐pot, three‐component condesation of aldehydes, maleic hydrazide, and dimedone using a green and inexpensive Brönsted acidic ionic liquid 1‐methyl‐2‐pyrrolidinone hydrosulfate ([Hnmp]HSO4) as catalyst under solvent‐free conditions. The method provided several advantages such as milder conditions, shorter reaction time, high yields, and environmentally benign procedure. 相似文献
Ethyl 2‐(2,6‐dioxocyclohexyl)‐2‐oxoacetate was prepared by reacting cyclohexane‐1,3‐dione ( 1 ) and diethyl oxalate ( 2 ) with the help of sodium ethoxide in ethanol at 0–5°C. Subsequent treatment of ethyl 2‐(2,6‐dioxocyclohexyl)‐2‐oxoacetate with hydrazine hydrate in ethanol resulted into ethyl 4‐oxo‐4,5,6,7‐tetrahydro‐2H‐indazole‐3‐carboxylate while without solvent in excess hydrazine hydrate on reflux resulted into 4‐oxo‐4,5,6,7‐tetrahydro‐2H‐indazole‐3‐carbohydrazide ( 3 ). The synthesis of novel indazole bearing oxadiazole derivatives (ODZ 01 to 16) has been achieved by the reaction of hydrazide of 2H‐indazole ( 3 ) with acid ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o , 4p ) in the presence of POCl3, and the antimicrobial activity of synthesized novel compounds has been studied. 相似文献
The combination of Pd/C–CuI–PPh3 has been identified as an efficient catalytic system for the C–C bond formation between 6‐bromo‐3‐iodo‐1H‐indazole and terminal alkynes in ethanol. Mono and/or dialkynyl‐substituted indazoles can be prepared using this general and practical methodology in good to excellent yields. Some of the compounds synthesized were tested for cytotoxic activities in vitro. 相似文献
Summary: Polypeptide‐shelled poly(propylene imine) dendrimers were realized by ring‐opening polymerization of α‐amino acid N‐carboxyanhydrides, initiated by dendrimers as core molecules. Polypeptides with 2nd generation core were used as model compounds to investigate interior complexes between metal ion and surface‐modified dendrimers. Micro‐calorimetric measurements outlined the formation of approximate 1:1 complexes between CuII and polypeptide‐shelled dendrimers and the influence of polypeptide chain compositions on differential molar heats of complexation.
Composition of one of the polypeptides synthesized. 相似文献
New four‐substituted indazoles 4a–e were synthesized by regioselective nucleophilic substitution of hydrogen of N‐alkyl‐7‐nitroindazoles 2a,b with arylacetonitriles 3a–c . Compounds 4a–e were reacted with arylsulfonyl chloride in pyridine to give some new indazole linked sulfonamides with good yields. The SNH at position C‐4 of 7‐nitroindazole with arylacetonitrile is confirmed by X‐ray diffraction analysis of compounds 4e and 6a . 相似文献
Electrophilic trisubstituted ethylene monomers, alkyl ring‐substituted 2‐phenyl‐1,1‐dicyanoethylenes, RC6H4CH?C(CN)2 (where R is 2‐methyl, 3‐methyl,4‐methyl, 4‐ethyl, 4‐isopropyl, 4‐butyl, and 4‐t‐butyl), were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, 1H‐ and 13C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C‐NMR, GPC, DSC, and TGA. High Tg of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 190–700°C range. 相似文献
Carbosilane dendrimers bearing galabiose (Galα1-4Gal) with three, four, and six galabiose units at the periphery of the dendrimers were synthesized for use as artificial inhibitors against Shiga toxins (Stxs) produced by Escherichia coli O157:H7. The galabiose unit, prepared from penta-O-acetyl-β-d-galactopyranose, was linked with carbosilane dendrimers of three shapes to afford acetyl-protected glycodendrimers in good yields. De-O-acetylation of the clusters was carried out in the presence of NaOMe and then aq NaOH to give the desired three shapes of galabiose-coated carbosilane dendrimers. Their biological activities toward Stxs were evaluated by kinetic analysis, binding assays, and cytotoxic assays. 相似文献
The 1‐{[(1H‐1,2,3‐Triazol‐4‐yl)methoxy]phenyl}‐1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives 5 were synthesized by a simple and efficient method, i.e., by the four‐component, one‐pot condensation reaction of phthalohydrazide 4 , a (propargyloxy)benzaldehyde 1 , an active methylene compound 3 (malononitrile or ethyl cyanoacetate), and an azide 2 in the presence of Cu(OAc)2/sodium L ‐ascorbate as catalyst and 1‐methyl‐1H‐imidazolium trifluoroacetate ([Hmim](CF3COO)) as an ionic‐liquid medium in good to excellent yields (Scheme 1). 相似文献
A series of urea‐derived heterocycles, 5N‐substituted hexahydro‐1,3,5‐triazin‐2‐ones, has been prepared and their structures have been determined for the first time. This family of compounds only differ in their substituent at the 5‐position (which is derived from the corresponding primary amine), that is, methyl ( 1 ), ethyl ( 2 ), isopropyl ( 3 ), tert‐butyl ( 4 ), benzyl ( 5 ), N,N‐(diethyl)ethylamine ( 6 ), and 2‐hydroxyethyl ( 7 ). The common heterocyclic core of these molecules is a cyclic urea, which has the potential to form a hydrogen‐bonding tape motif that consists of self‐associative (8) dimers. The results from X‐ray crystallography and, where possible, Laue neutron crystallography show that the hydrogen‐bonding motifs that are observed and the planarity of the hydrogen bonds appear to depend on the steric hindrance at the α‐carbon atom of the N substituent. With the less‐hindered substituents, methyl and ethyl, the anticipated tape motif is observed. When additional methyl groups are added onto the α‐carbon atom, as in the isopropyl and tert‐butyl derivatives, a different 2D hydrogen‐bonding motif is observed. Despite the bulkiness of the substituents, the benzyl and N,N‐(diethyl)ethylamine derivatives have methylene units at the α‐carbon atom and, therefore, display the tape motif. The introduction of a competing hydrogen‐bond donor/acceptor in the 2‐hydroxyethyl derivative disrupts the tape motif, with a hydroxy group interrupting the N? H???O?C interactions. The geometry around the hydrogen‐bearing nitrogen atoms, whether planar or non‐planar, has been confirmed for compounds 2 and 5 by using Laue neutron diffraction and rationalized by using computational methods, thus demonstrating that distortion of O‐C‐N‐H torsion angles occurs to maintain almost‐linear hydrogen‐bonding interactions. 相似文献
Isoxazolo[5,4‐d]pyrimidine‐4,6(5H,7H)diones 2a – 2f have been synthesized from the reaction of ethyl 5‐amino‐3‐methyl‐4‐isoxazole carboxylate ( 1 ) with aryl isocyanates in the presence of Keggin heteropolyacid H3[PW12O40] as a green solid acid catalyst at room temperature in a one‐pot process in good yields. 相似文献
New calixarene‐based dendrimers, containing calix[4]arene as the core and different generations of Fréchet‐type poly(benzyl ether) dendrons as building blocks, which possess either Br‐atoms or COOtBu groups at their surface were synthesized and presented herein for the first time. The new calix[4]arene‐cored dendritic macromolecules were fully characterized and found to prefer strictly the cone conformation. 相似文献
An etiobilirubin‐IIβ analog with the central C(10) CH2 group replaced by a diacetylene unit ( 1 ) was synthesized by base‐catalyzed condensation of bis‐[3‐methyl‐4‐ethyl‐5‐formylpyrrol‐2‐yl]‐diacetylene ( 3 ) with 3‐methyl‐4‐ethyl‐5‐p‐toluenesulfonyl‐2‐pyrrolinone ( 10 ). Diacetylenic rubin 1 is a dark red solid, giving orange solutions with uv‐visible absorption maxima near 460 nm. 相似文献
Synthesis of the title compounds 4(a – i) was accomplished through a two‐step process. The synthetic route involves the cyclization of equimolar quantities of 2,2′‐methylene(methyl)bis(4,6‐di‐tert‐butyl‐phenol) ( 1 ) with tris‐(2‐chloro‐ethyl) phosphite ( 2a ), tris‐(2‐bromo‐ethyl) phosphine ( 2b ), and tris‐bromo methyl phosphine ( 2c ) in the presence of sodium hydride in dry tetrahydrofuran at 45–50°C. They were further converted to the corresponding oxides, sulfides, and selenides under N2 atmosphere by reacting them with hydrogen peroxide, sulfur, and selenium, respectively ( 4a – c , 4d – f, and 4g – i ). But the compounds 6a , b were prepared by the direct cyclocondensation of equimolar quantities of 1 with (2‐chloro‐ethyl)‐phosphonic acid dibromomethyl ester ( 5a ) and (2‐chloro‐ethyl)‐phosphonic acid bis(2‐bromo‐ethyl) ester ( 5b ) in the presence of sodium hydride in dry tetrahydrofuran at 45–50°C in moderate yields. All the newly synthesized compounds 4 ( a – i ) and 6 ( a – b ) exhibited moderate in vitro antibacterial and antifungal activities. 相似文献