Hydroacridines: Part 23. 1H and 13C NMR spectra of sym‐octahydroacridine,its 9‐(3‐pyridyl) and 9‐(4‐pyridyl) derivatives and the corresponding N(10)‐oxides. An experimental approach to the diamagnetic anisotropy of the pyridine nucleus

The complete ¹H NMR chemical shift assignments of 1,2,3,4,5,6,7,8‐octahydroacridine ( 1 ), 1,2,3,4,5,6,7,8‐octahydro‐9‐(3‐pyridyl)acridine ( 2 ), 1,2,3,4,5,6,7,8‐octahydro‐9‐(4‐pyridyl)acridine ( 3 ) and the corresponding N(10)‐oxides 1a , 2a and 3a , respectively, were achieved on the basis of 400 MHz ¹H NMR spectra and proton–proton decoupling, HMQC and NOEDIFF experiments. The spectral data for the above compounds provided the first experimental evidence of the difference in the anisotropy effect of the two non‐symmetrical moieties of the pyridine nucleus, and allowed us to ascertain that the shielding effect of the moiety defined by the C(2′)—N—C(6′) atoms is weaker than that of the C(3′)—C(4′)—C(5′) moiety. The ¹³C NMR spectra of 1 – 3 and 1a – 3a and the effect of N(10)‐oxidation on the ¹³C NMR chemical shifts are also discussed. The N‐oxidation of 2 and 3 with m‐chloroperbenzoic acid occurred regiospecifically, affording the N(10)‐oxides 2a and 3a free of N(1′)‐oxide isomers. Copyright © 2002 John Wiley & Sons, Ltd.     

H‐transfer reaction during decomposition of N‐(2‐methylpropyl)‐ N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐N‐oxyl (SG1)‐based alkoxyamines

Thermal decomposition of four tertiary N‐(2‐methylpropyl)‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐N‐oxyl (SG1)‐based alkoxyamines (SG1‐C(Me)₂‐C(O)‐OR, R = Me, tBu, Et, H) has been studied at different experimental conditions using ¹H and ³¹P NMR spectroscopies. This experiment represents the initiating step of methyl methacrylate polymerization. It has been shown that H‐transfer reaction occurs during the decomposition of three alkoxyamines in highly degassed solution, whereas no products of H‐transfer are detected during decomposition of SG1‐MAMA alkoxyamine. The value of the rate constant of H‐transfer for alkoxyamines 1 (SG1‐C(Me)₂‐C(O)‐OMe) and 2 ( SG1‐C(Me)₂‐C(O)‐OtBu) has been estimated as 1.7 × 10³ M^?1s^?1. The high influence of oxygen on decomposition mechanism is found. In particular, in poorly degassed solutions, nearly quantitative formation of oxidation product has been observed, whereas at residual pressure of 10^?5 mbar, the main products originate from H‐atom transfer reaction. The acidity of the reaction medium affects the decomposition mechanism suppressing the H‐atom transfer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

One‐step synthesis of 6‐acetamido‐3‐(N‐(2‐(dimethylamino) ethyl) sulfamoyl) naphthalene‐1‐yl 7‐acetamido‐4‐hydroxynaphthalene‐2‐sulfonate and its characterization with 1D and 2D NMR techniques

A one‐step method was reported for the synthesis of 6‐acetamido‐3‐(N‐(2‐(dimethylamino) ethyl) sulfamoyl) naphthalene‐1‐yl 7‐acetamido‐4‐hydroxynaphthalene‐2‐sulfonate by treating 7‐acetamido‐4‐hydroxy‐2‐naphthalenesulfonyl chloride with equal moles of N, N‐dimethylethylenediamine in acetonitrile in the presence of K₂CO₃. The chemical structure of the obtained compounds was characterized by MS, FTIR, ¹H NMR, ¹³C NMR, gCOSY, TOCSY, gHSQC, and gHMBC. The chemical shift differences of ¹H and ¹³C being δ 0.04 and 0.2, respectively, were unambiguously differentiated. Copyright © 2013 John Wiley & Sons, Ltd.     

Configuration and conformation of a novel uridine analogue: 1H and 13C NMR spectra of (5'S)‐1‐[2'‐(2‐hydroxyethyl)tetrahydropyran‐5'‐yl]‐1H‐pyrimidine‐2,4‐dione

A combination of homo‐ and heteronuclear 1D and 2D NMR techniques provided the assignment of the ¹H and ¹³C resonances of the major component of a reaction product consisting of the two possible diastereomers of (5^′S)‐1‐[2^′‐(2‐hydroxyethyl)tetrahydropyran‐5^′‐yl]‐1H‐pyrimidine‐2,4‐dione and showed that the tetrahydropyranyl ring in the major 5^′S,2^′S‐isomer adopts the twist conformation. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis of phosphorylated 1,3,5‐oxadiazines via N‐acyltrifluoroacetimidoylphosphonates

N‐Benzoyl‐ and N‐methoxycarbonyltrifluoroacetimidoylphosphonates react with dimethylcyanamide in a [4+2]‐cycloaddition to give 4‐phosphorylated 1,3,5‐oxadiazines. The structures of the products were confirmed by NMR (¹H, ¹³C, ¹⁹F, ³¹P) and IR spectra and by XRD analysis. © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:22–26, 2002; DOI 10.1002/hc.1102     

Synthesis and biological activity of novel N‐tert‐butyl‐N,N′‐substitutedbenzoylhydrazines containing 2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl

In a search for new insect growth regulators with unusual biological properties and different activity spectrum, we thought that the preservation of the bioactive unit and the introduction of 2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl in N‐tert‐butyl‐N,N′‐dibenzoylhydrazine would enhance their larvicidal activities to a significant degree. Therefore, we designed and synthesized N′‐tert‐butyl‐N′‐[2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl]‐N‐benzoylhydrazine and analogs by two procedures. These novel compounds were characterized by elemental analyses, IR, and ¹H NMR. At the same time, N‐tert‐butyl‐N‐substitutedbenzoylhydrazines were prepared by a new method, and some reactions involved were studied. The preliminary results indicate that some compounds have inhibitory effects against plant pathogenetic bacteria such as early blight of tomato. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]‐pyrimidine‐6‐carboxamides

Possible approaches to synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]pyrimidine‐6‐carboxamides 4 have been discussed. It is shown that the preferable approach is cyclization of 2‐iminocoumarin‐3‐carboxamides 1 , utilizing 5‐amino‐3‐methyl‐N²‐arylthiophene‐2,4‐dicarboxamides 2 as binucleophilic reagents. The proposed procedure allowed us to easily obtain 4 in two stages, using common reagents. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:341–346, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20303     

Supramolecular architectures in two 1:1 cocrystals of 5‐fluorouracil with 5‐bromothiophene‐2‐carboxylic acid and thiophene‐2‐carboxylic acid

In solid‐state engineering, cocrystallization is a strategy actively pursued for pharmaceuticals. Two 1:1 cocrystals of 5‐fluorouracil (5FU; systematic name: 5‐fluoro‐1,3‐dihydropyrimidine‐2,4‐dione), namely 5‐fluorouracil–5‐bromothiophene‐2‐carboxylic acid (1/1), C₅H₃BrO₂S·C₄H₃FN₂O₂, (I), and 5‐fluorouracil–thiophene‐2‐carboxylic acid (1/1), C₄H₃FN₂O₂·C₅H₄O₂S, (II), have been synthesized and characterized by single‐crystal X‐ray diffraction studies. In both cocrystals, carboxylic acid molecules are linked through an acid–acid R ₂²(8) homosynthon (O—H…O) to form a carboxylic acid dimer and 5FU molecules are connected through two types of base pairs [homosynthon, R ₂²(8) motif] via a pair of N—H…O hydrogen bonds. The crystal structures are further stabilized by C—H…O interactions in (II) and C—Br…O interactions in (I). In both crystal structures, π–π stacking and C—F…π interactions are also observed.     

Structural studies of (prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine hetero‐scorpionate copper complexes

The structures of five compounds consisting of (prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine complexed with copper in both the Cu^I and Cu^II oxidation states are presented, namely chlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(I) 0.18‐hydrate, [CuCl(C₁₅H₁₇N₃)]·0.18H₂O, (1), catena‐poly[[copper(I)‐μ₂‐(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ⁵N,N′,N′′:C²,C³] perchlorate acetonitrile monosolvate], {[Cu(C₁₅H₁₇N₃)]ClO₄·CH₃CN}_n, (2), dichlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II) dichloromethane monosolvate, [CuCl₂(C₁₅H₁₇N₃)]·CH₂Cl₂, (3), chlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II) perchlorate, [CuCl(C₁₅H₁₇N₃)]ClO₄, (4), and di‐μ‐chlorido‐bis({(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II)) bis(tetraphenylborate), [Cu₂Cl₂(C₁₅H₁₇N₃)₂][(C₆H₅)₄B]₂, (5). Systematic variation of the anion from a coordinating chloride to a noncoordinating perchlorate for two Cu^I complexes results in either a discrete molecular species, as in (1), or a one‐dimensional chain structure, as in (2). In complex (1), there are two crystallographically independent molecules in the asymmetric unit. Complex (2) consists of the Cu^I atom coordinated by the amine and pyridyl N atoms of one ligand and by the vinyl moiety of another unit related by the crystallographic screw axis, yielding a one‐dimensional chain parallel to the crystallographic b axis. Three complexes with Cu^II show that varying the anion composition from two chlorides, to a chloride and a perchlorate to a chloride and a tetraphenylborate results in discrete molecular species, as in (3) and (4), or a bridged bis‐μ‐chlorido complex, as in (5). Complex (3) shows two strongly bound Cl atoms, while complex (4) has one strongly bound Cl atom and a weaker coordination by one perchlorate O atom. The large noncoordinating tetraphenylborate anion in complex (5) results in the core‐bridged Cu₂Cl₂ moiety.     

Decomposition of model alkoxyamines in simple and polymerizing systems. II. Diastereomeric N‐(2‐methylpropyl)‐N‐(1‐diethyl‐phosphono‐2,2‐dimethyl‐propyl)‐aminoxyl‐based compounds

Thermal reactions of the alkoxyamine diastereomers DEPN‐R′ [DEPN: N‐(2‐methylpropyl)‐N‐(1‐diethylphosphophono‐2,2‐dimethyl‐propyl)‐aminoxyl; R′: methoxy‐carbonylethyl and phenylethyl] with (R,R) + (S,S) and (R,S) + (S,R) configurations have been investigated by ¹H NMR at 100 °C. During the overall decay the diastereomers interconvert, and an analytical treatment of the combined processes is presented. Rate constants are obtained for the cleavage and reformation of DEPN‐R′ from NMR, electron spin resonance, and chemically induced dynamic nuclear polarization experiments also using 2,2,6,6‐tetramethylpiperidinyl‐1‐oxyl (TEMPO) as a radical scavenger. The rate constants depend on the diastereomer configuration and the residues R′. Simulations of the kinetics observed with styrene and methyl methacrylate containing solutions yielded rate constants for unimeric and polymeric alkoxyamines DEPN‐(M)_n‐R′. The results were compatible with the known DEPN mediation of living styrene and acrylate polymerizations. For methyl methacrylate the equilibrium constant of the reversible cleavage of the dormant chains DEPN‐(M)_n‐R′ is very large and renders successful living polymerizations unlikely. Mechanistic and kinetic differences of DEPN‐ and TEMPO‐mediated polymerizations are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3264–3283, 2002     

Synthesis and NMR characteristics of N‐acetyl‐4‐nitro,N‐acetyl‐5‐nitro,N‐acetyl‐6‐nitro and N‐acetyl‐7‐nitrotryptophan methyl esters

N‐acetyl‐4‐nitrotryptophan methyl ester (2), N‐acetyl‐5‐nitrotryptophan methyl ester (3), N‐acetyl‐6‐nitrotryptophan methyl ester (4) and N‐acetyl‐7‐nitrotryptophan methyl ester (5) were synthesized through a modified malonic ester reaction of the appropriate nitrogramine analogs followed by methylation with BF₃‐methanol. Assignments of the ¹H and ¹³C NMR chemical shifts were made using a combination of ¹H–¹H COSY, ¹H–¹³C HETCOR and ¹H–¹³C selective INEPT experiments. Copyright © 2008 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

NMR analysis of 6‐(2′,3′‐dihydro‐1′H‐inden‐1′‐yl)‐1H‐indene

¹H, ¹³C and two‐dimensional NMR analyses were applied to determine the NMR parameters of 6‐(2′,3′‐dihydro‐1′H‐inden‐1′‐yl)‐1H‐indene. The measurements were accomplished with 0.5 mg of the substance, this quantity being sufficient to determine the chemical shifts of all the H and C atoms, and also the appropriate coupling constants and to give the complete NMR resonance assignments of the molecule. The predicted patterns of the four different H atoms of the methylene groups of the indane structural element coincided completely with the complex patterns in the NMR spectra. Copyright © 2002 John Wiley & Sons, Ltd.     

Complete assignment of the 1H and 13C NMR spectra of some N‐benzyl‐(piperidin or pyrrolidin)‐purines

The ¹H and ¹³C shifts of six N‐benzyl‐(piperidin or pyrrolidin)‐purines were fully assigned by a combination of HSQC and HMBC experiments. The ¹H,¹H coupling constants were also determined. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis and Herbicidal Activity of 2‐Alkyl(aryl)‐4‐amino‐3‐[alkyl(alkoxy)carbonyl]‐5‐cyano‐6‐[(3‐trifluoromethyl)phenoxy]‐pyridines

To find novel bleaching herbicide lead compounds, a series of novel 2‐alkyl(aryl)‐4‐amino‐3‐[alkyl(alkoxy)carbonyl]‐5‐cyano‐6‐[(3‐trifluoromethyl)phenoxy]‐pyridines was designed and synthesized by the multistep reactions. N,S‐acetal 1 reacted with 2 to obtain multisubstituted pyridines 3 in the presence of zinc nitrate as the catalyst. The target compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l were formed by the oxidation of 3 , followed by the substitution with 3‐(trifluoromethyl)phenol in the presence of potassium carbonate. Their structures were confirmed by IR, ¹H NMR, EI‐MS, and elemental analyses. The preliminary bioassays indicated that some of them displayed moderate herbicidal activity against dicotyledonous weed Brassica campestris L at the concentration of 100 mg/L.     

Synthesis,characterization, X‐ray crystal structure and in vitro antitumour activity of sodium bis(2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylato)triphenylstannate

Sodium bis[2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylato]triphenylstannate, [(CH₃OCH₂CH₂OCH₂CH₂OCH₂CH₂)‐1,2‐C₂B₁₀H₁₀‐9‐COO)₂SnPh₃]^? Na⁺, compound 1, was synthesized by the 1:1 condensation of triphenyltin(IV) hydroxide with 2‐(3′,6′,9′‐trioxadecyl)‐1,2‐dicarba‐closo‐dodecaborane‐1‐carboxylic acid and crystallized in the presence of sodium bicarbonate. Its structure was determined by spectroscopy, elemental analysis and X‐ray diffraction. The structure of 1 consists of trigonal bipyramidal [Sn(Ph)₃(L)₂]^? anions and Na⁺ cations coordinated by oxygen atoms of polyoxaalkyl chains of different stannate anions, forming cation–anion chains elongated along the c axis. Compound 1 is significantly more active in vitro against seven tumour cell lines of human origin than 5‐fluorouracil, cis‐platin, carboplatin, and previously reported organotin carboranecarboxylates, but is less active than organotin polyoxaalkylcarboxylates. Copyright © 2004 John Wiley & Sons, Ltd.     

Kinetics of the reactions of OH with 3‐methyl‐2‐cyclohexen‐1‐one and 3,5,5‐trimethyl‐2‐cyclohexen‐1‐one under simulated atmospheric conditions

Relative rate coefficients for the reactions of OH with 3‐methyl‐2‐cyclohexen‐1‐one and 3,5,5‐trimethyl‐2‐cyclohexen‐1‐one have been determined at 298 K and atmospheric pressure by the relative rate technique. OH radicals were generated by the photolysis of methyl nitrite in synthetic air mixtures containing ppm levels of nitric oxide together with the test and reference substrates. The concentrations of the test and reference substrates were followed by gas chromatography. Based on the value k(OH + cyclohexene) = (6.77 ± 1.35) × 10^?11 cm³ molecule^?1 s^?1, rate coefficients for k(OH + 3‐methyl‐2‐cyclohexen‐1‐one) = (3.1 ± 1.0) × 10^?11 and k(OH + 3,5,5‐trimethyl‐2‐cyclohexen‐1‐one) = (2.4 ± 0.7) × 10^?11 cm³ molecule^?1 s^?1 were determined. To test the system we also measured k(OH + isoprene) = (1.11 ± 0.23) × 10^?10 cm³ molecule^?1 s^?1, relative to the value k(OH + (E)‐2‐butene) = (6.4 ± 1.28) × 10^?11 cm³ molecule^?1 s^?1. The results are discussed in terms of structure–activity relationships, and the reactivities of cyclic ketones formed in the photo‐oxidation of monoterpene are estimated. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 7–11, 2002     

Towards the Synthesis of 1‐Deoxy‐1‐nitropiperidinoses

In the course of the first of several attempts to elaborate methods for the synthesis of 1‐nitropiperidinoses, lincosamine was transformed into lactam 6 via hemiacetal 1 , lactone 2 , amide 3 , oxo amide 4 , and its cyclic tautomer 5 . Treatment of the N‐Boc‐protected lactam oxime 9 , obtained from lactam 6 , with brominating agents failed to provide the bromonitroso carbamate 10 . The N‐Boc‐protected lactam 13 derived from 6 was reduced to hemiacetal 14 , but the corresponding N‐Boc‐aminooxime did not tautomerise to the C(1)‐hydroxylamine, and nitrone 17 , a potential precursor of the nitropiperidine 12 , was not formed. Oxidation of the anomeric azide 20 with HOF?MeCN failed to provide the expected nitropiperidine 21 . The phosphinimines 22 derived from 20 did not react with O₃. In the next approach to 1‐nitropiperidinoses, we treated the N‐Boc‐protected hemiacetal 25 , obtained from the known gluconolactam 23 with N‐benzylhydroxylamine. The resulting nitrone 26 exits in equilibrium with the anomeric N‐benzyl‐glycosylhydroxylamine that was oxidized to the anomeric nitrone 28 . Ozonolysis of 28 led to the hemiacetal 25 , resulting from the desired, highly reactive protected nitropiperidinose 29 , that was evidenced by an IR band at 1561 cm^?1. Similarly to the synthesis of nitrone 26 , reaction of the N‐tosyl‐protected hemiacetal 31 with N‐benzylhydroxylamine and oxidation provided the anomeric N‐benzylhydroxylamines 33 via the p‐toluenesulfonamido nitrone 32 . Their oxidation with MnO₂ led to the anomeric nitrone 34 . Ozonolysis of 34 as evidenced by ¹H‐NMR and ReactIR spectroscopy led to the highly reactive nitropiperidinose 35 . Like 29, 35 was transformed during workup, and only the hemiacetal 31 was isolated. The similarly prepared lincosamine‐derived nitrone 17 was subjected to ReactIR‐monitored ozonolysis that evidenced the formation of the protected nitropiperidinose 12 , but only led to the isolation of 14 . The facile transformation of the nitropiperidinoses to hemiacetals is rationalised by heterolysis of the anomeric C,N bond, recombination of the ion pair, and denitrosation of the resulting anomeric nitrite by a nucleophile. Attempts to convert the 1‐deoxy‐1‐nitropiperidinose 35 to uloses 43 by base‐catalysed Michael additions or Henry reactions were unsuccessful.     

Synthesis of 2‐substituted‐2,3‐dihydro‐5‐benzoyl‐1H‐1,3,2‐benzodiazaphosphole 2‐oxides/sulfides

Syntheses of 2‐aryloxy/2‐chloro ethoxy‐2,3‐dihydro‐5‐benzoyl‐1H‐1,3,2‐benzodiaza‐phosphole 2‐oxides 3a–h were accomplished by reactions of equimolar quantities of 3,4‐diaminobenzophenone ( 1 ) with various aryl/chloroethoxy phosphorodichloridates 2a–g and 2h in the presence of triethylamine at 50–60°C. Compounds 3i–k were prepared by reacting 3,4‐diaminobenzophenone ( 1 ) with aryl thiophosphorodichloridates 2i–k under similar conditions. They were characterized by IR, ¹H, ¹³C, and ³¹P NMR spectral data. Some of these products possessed siginificant antimicrobial activity © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:340–345, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10044     

NMR studies on 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one

An unsymmetrical heterocyclic diamine, 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one, was synthesized. Its ¹H and ¹³C NMR spectra were completely assigned by utilizing the two‐dimensional heteronuclear ¹³C–¹H multiple‐bond coherence (HMBC) spectroscopy, and heteronuclear ¹³C–¹H one‐bond correlation spectroscopy, homonuclear shift correlation spectroscopy (H,H‐COSY) and rotating frame Overhauser enhancement spectroscopy (ROESY). The structure of the compound was shown to be the phthalazinone rather than the phthalazine ether from cross peaks and chemical shifts of the protons. Copyright © 2002 John Wiley & Sons, Ltd.     

N‐(Substituted benzyl)‐3,5‐bis(benzylidene)‐4‐piperidones: Synthesis and Preliminary Anti‐leukemia Activity (I)

A series of novel N‐(substituted benzyl)‐3,5‐bis(benzylidene)‐4‐piperidones 5a – 5o were synthesized with substituted benzylamines as raw materials via a series of Michael addition, Dieckmann condensation, hydrolysis decarboxylation and aldol condensation. The structures were confirmed by ¹H NMR, IR, MS techniques and elemental analysis. Assay‐based antiproliferative activity study using leukemic cell lines K562 revealed that most of the title compounds have high effectiveness in inhibiting leukemia K562 cells proliferation, among which the compounds 5g (IC₅₀=7.81 µg·mL⁻¹), 5k (IC₅₀=6.35 µg·mL⁻¹), 5l (IC₅₀=7.20 µg·mL⁻¹), and 5o (IC₅₀=5.79 µg·mL⁻¹) have better inhibition activities than standard 5‐fluorouracil (IC₅₀=8.56 µg·mL⁻¹).