Synthesis and Crystal Structure of 4-（4-Chlorophenyl）-6-methyl-5-methoxy-caronyl-3,4-dihydropyrimidin-2（H）-one

1 INTRODUCTION Biginelli reaction is a three-component condensa-tion of ethyl acetoacetate, benzaldehyde and urea forthe synthesis of 3,4-dihydropyrimidin-2(1H)-ones(Scheme 1). The reaction can be carried out in aone-pot fashion in alcohol solution in t…     

Characterization of 4-Aryl-5-ethoxycarbonyl-6-methyl-3,4-dihydro- pyrimidin-2 （1H）-thiones by EI-TOF Mass Spectrometry

IntroductionIn1893,Pietro Biginelli reported the first synthe-sis(termed the Biginelli reaction)of3,4-dihydropyrim-idinone(denoted as“oxo-orO-Biginelli compound”in-cluding its derivatives,type A in Scheme1).In thelast decade,interest in these compounds …     

Synthesis and Crystal Structure of 4-（4-Bromophenyl）- 3,4-dihydro-6-methyl quinolin-2（1H）-one

The title compound (C16H14BrNO) has been synthesized by the reaction of p-tolylamine, Meldrum’s acid and 4-bromo-benzaldehyde, and its structure was characterized by IR, 1H NMR and X-ray single-crystal diffraction. The crystal belongs to monoclinic, space group P21/n with a = 7.6850(11), b = 8.3004(11), c = 21.301(3) , β = 95.110(2)°, V = 1353.4(3) 3, Mr = 316.19, Z = 4, Dc = 1.552 g/cm3, μ(MoKα) = 3.028 mm-1, F(000) = 640, the final R = 0.0345 and wR = 0.0768. X-ray analysis reveals that the atoms of C(1), C(2), C(3), C(4), C(5) and N(1) form a six-membered ring of boat conformation.     

One—Pot Synthese of 3,4—Dihydropyrimidine—2（1H）—thiones Catalyzed by La（OTf）3

A general and practical procedure for the syntheses of 3,4-di-hydropyrimidine-2(1H)-thiones by a one-pot condensation of aldehyde,β-ketoester or β-diketone and thiourea using La(OTf)3 as the catalyst is described.Mild reaction conditions,excellent yields as well as the environmentally friendly character of La(OTf)3 make it an important alternative to the classic acid-catalyzed Biginelli‘s reaction.     

One—pot Synthesis of 3,4—dihydropyrimidin—2（1H）—one Using TsOH as a Catalyst under Microwave Irradiation

A series of Biginelli compounds was synthesized using TsOH as a catalyst under microwave irradiation.This simple method provided the title compounds in 86%-98% yields by the reaction of aromatic aldehydes with 1,3-carbonyl compound and urea.The structure of 40 was determined by single crystal Xray diffraction analysis.     

Synthesis and Crystal Structure of 1,7,7-Trimethyl- 4-（4-methoxyphenyl）-4,6,7,8-tetrahydroquinoline- 2,5（1H,3H）-diones under Microwave Irradiation

1 INTRODUCTION Various quinolone derivatives are known to dis- play interesting biological properties ranging from microbial activity to cytotoxicity[1]. They have been reported as antiviral (HIV-1)[2] and antitumor agents[3] as well as used as tubulin[4], topoisomerase[5] and thrombocyte inhibitors[6]. As a member of the quino- lone family, substituted N-phenyl-2-quinolones re-present the structural basis of many biologically active compounds, such as protein kinase inhibitors, immunodu…     

Crystal Structure and DFT Studies of a Triazole Derivative： 4- （ 2-Hydrobenzylideneamino ） -3- （ 1,2,4-triazol-4-ylmethyl） 1H-1, 2,4-triazole-5 （4H） -thione

A novel triazole derivative 4-(2-hydrobenzylideneamino)-3-(1,2,4-triazol-4-ylmethyl)-1H-1,2,4-triazole-5(4H)-thione(1) was synthesized and characterized using elemental analysis, FTIR, and 1H NMR, and its crystal structure was determined via X-ray single crystal diffraction analysis. Crystal data: monoclinic, P2(1)/c, a=0.83335(9) nm, b=1.49777(16) nm, c=1.14724(12) nm, β =107.990(2)°, D=1.470 Mg/m3, and Z=4. The geometries and the vibrational frequencies were determined using the density functional theory(DFT) method at the B3LYP/ 6-31G level. To demonstrate the accuracy of the reaction route of compound 1, one of the important intermediates was also tested using the same method. The structural parameters of the two compounds calculated using the DFT study are close to those of the crystals, and the harmonic vibrations of the two compounds computed via the DFT method are in good agreement with those in the observed IR spectral data. The thermodynamic properties of the title compound were calculated, and the compound shows a good structural stability at normal temperature. The test results of biological activities show that it has a certain bactericidal ability.     

Comparative Studies on Mass Spectrometric Fragmentation of Linear Chiral Secondary Alcohols （ R ） -1-（4-Alkylphenyl） and （ R ） -1- （ 4-Alkoxyphenyl/Alkylthiophenyl ） Alcohols

Introduction Chiralsecondaryalcoholsareveryimportantinter mediatesinorganicsynthesis.Theyaregenerallypre paredviachemicalorenzymaticresolutionofracemic secondaryalcohols[1—4],chemicalorenzymaticasym metricreductionofprochiralketones[5—7],andasym metrica…     

Synthesis, Crystal Structure and Antibacterial Activities of 3-[（2-Hydroxy-4-diethylamino-phenyl）methylenehydrazinocarbonyl]-4-hydroxy-6-methyl-2（1H）-pyridinones

1 INTRODUCTION Recently, compounds containing pyrazole, imida- zole, triazole (including benzotriazole), pyridine, tetrazole and indole have attracted much interest because of their fungicidal activity, plant-growth regulating activity and antibacterial activity[1～3]. Schiff bases also constitute a good type of biolo- gically active substructures[4～7]. Studies of pyri- dine Schiff base-type fungicides have been repor- ted[8]. However, some structures of pyridine com- pounds containing h…     

5-乙氧羰基-4-取代-6-甲基-3,4-二氢嘧啶-2(1H)-酮的电子轰击飞行时间质谱表征

The electron ionization time-of-flight (TOF) mass spectra of a series of 5-ethoxycarbonyl-4-substituted-6-methyl-3,4-dihydropyrimidin-2(1H)-ones were studied to establish their fragmentation processes. Using the high resolution capabilities of the TOF instrument, exact masses for each fragment were determined. These data were used to infer molecular formulas and elemental compositions for all molecular ions and fragments through software interpretation and according to the established fragmentation rules the majority of ions were fully assigned. Two main fragmentation routes can be found in this work. First of them, for all the title compounds, includes the formation of three cations, by loss of R1 from the position 4, C2H4 (via a McLafferty rearrangement) from the ester group and H2O via a cyclic-six-membered transition state. The second route, for 4-aromatic compounds, consists of the formation of a cation by loss of EtCO2. Several additional fragmentations for individual compounds are proposed.     

5-乙酰(苯甲酰)基-4-芳基-3,4-二氢嘧啶-2(1H)-酮的质谱裂解规律

Using high resolution capabilities of a time-of-flight instrument and ion trap tandem technique, electron impact mass spectra of 5-acetyl (benzoyl)-4-aryl-3,4-dihydropyrimidin-2 (1H)-ones 1-5 were studied. The molecular ion (M) peaks for 1-3 can be found in the spectra with high abundances, but very weak for 4 and 5,in which strong electron-attracting substituents are attached to the benzene ring. The main fragmentation pathways for 1-5 include the cleavage of (M-Ar) + with high intensity, (M-RCO) + with moderate abundance, (M-H) +with high intensity for the compounds without strong electron-attracting substituent in the aromatic ring, and the pyrimidine ring cleavage (loss of neutral NH=C=X). In addition, a prominent cation (Ph + , m/z 77) can be found in the low mass region of the spectra for all the compounds, which give rise by different pathways between 1- 2 and 3-5. Several additional fragmentations for individual compounds are proposed.     

New Fragmentation Pathways for Cephalosporins by Electrospray Ionization Quadrupole Time-of-flight Mass Spectrometry

Introduction Cephalosporins are antibiotics of β-lactam family. They have a broad spectrum of antibiotic activity due to their ability to inhibit bacterial cell wall synthesis of different Gram-positive and Gram-negative bacteria. Cephalosporins are used orally or parenterally to treat a wide variety of infections throughout the body and are often prescribed to fight penicillin resistant microorganisms. They also find a common use in prophylaxis for surgical procedures where infections in the operating area could pose a serious risk[1,2].     

Photo-oxidation of 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones

A variety of Biginelli 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones are efficiently oxidized to their corresponding pyrimidin-2(1H)-one derivatives upon UV irradiation under argon atmosphere in chloroform solution. The nature of the additional substituent on the phenyl ring located on C-4 of the heterocyclic ring influences the rate of reaction. An electron-transfer induced photoreaction is proposed based on the formation of HCl and CH₂Cl₂.     

Synthesis under Microwave Irradiation and Crystal Structure of 4-（3,4-Methylenedioxylphenyl）-6-methyl- 5-ethoxycaronyl-3,4-dihydropyrimidin-2（H）-one

1 INTRODUCTION Since Biginelli firstly reported the synthesis of 3,4-dihydropyrimidin-2(1H)-ones in 1893, this com- pound has been found to emerge as calcium channel blockers, antihypersive agents and a-antagonists[1]. Consequently, this Biginelli reacti…     

一类2(1H)-喹喔啉化合物的裂解机理

用电子轰击质谱（EI-MS）研究了一类喹喔啉化合物；1-烷基-3-甲基-2（1H）-喹喔啉-2-酮（1-alkyl-3-methyl-2(1H)-quinoxalin-2-one，简称AMQ，其中alky1=H,CH3，C2H5，n-C3H7，n-C5H11；结果表明随着烷基链的增长，样品熔点通常会有所降低，结合在电子轰击下所产生的裂解碎片离子，并根据其结构特征为乙基化样品为代表，推导了该类化合物在电子轰击作用下可能发生的裂解机理。