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1.
The electrochemical oxidation of catechols (1a-c) has been studied in the presence of 6-methyl-1,2,4-triazine-3-thion-5-one 3 in aqueous sodium acetate, using cyclic voltammetry and controlled-potential coulometry. A plausible mechanism for the oxidation of catechols and their reaction with 3 is presented. All the catechol derivatives (1a-c) were converted into 7H-thiazolo[3,2-b]-1,2,4-triazin-7-one derivatives (6a-c) through a Michael-type addition reaction of 3 to anodically generated o-quinones. The electrochemical syntheses of 6a-c were successfully performed in one pot in an undivided cell using an environmentally friendly method with high atomic economy. 相似文献
2.
An efficient synthesis of 4-phenylquinolin-2(1H)-one derivatives has been achieved in a one-pot reaction from N-acyl-o-aminobenzophenones 1a-c (a: acyl=acetyl; b: acyl=propanoyl; c: acyl=heptanoyl) using NaH as a base. Treatment of 1 with NaH provided the quinolones 2a-c with 62-83% yields, whereas the reaction in the presence of alkyl iodide (alkyl=methyl, ethyl, n-octyl) gave the corresponding N-alkylated quinolones 3a-g in 75-95% yields. The alkylation reaction of 4-phenylquinolin-2(1H)-one 2a with alkyl halide gave a mixture of N-alkylated and O-alkylated products. Comparison of IR and NMR data of the N-alkylated and O-alkylated compounds with those of 2a-c indicated that 2a-c exist as the lactam form. 相似文献
3.
Natcharee Kongprakaiwoot 《Journal of organometallic chemistry》2004,689(21):3350-3356
Reactions of 1,4-dibromo-2,5-difluorobenzene with two equivalents of lithium diisopropylamide at low temperature (T < −90 °C) followed by a quench with a slight excess of ClPPh2 afford 1,4-dibromo-2,5-bis(diphenylphosphino)-3,6-difluorobenzene (1) in good yields. Reacting 1 with two equivalents of BuLi followed by a quench with a slight excess of ClPR2 yield novel 1,2,4,5-tetrakis(phosphino)-3,6-difluorobenzenes 1,4-(PPh2)2-2,5-(PR2)2-C6F2 (R = Ph (2a); R = iPr (2b); R = Et (2c)) in moderate yields. Compounds 1 and 2a-c were characterized by multinuclear NMR spectroscopy and elemental analyses. In addition, molecular structures of 2a-c have been determined by single crystal X-ray crystallography. Phosphorus atoms of PPh2/PR2 substituents in 2a-c are displaced from the plane of the central phenyl ring due to steric interactions with neighboring groups. 相似文献
4.
Naser Foroughifar Akbar Mobinikhaledi Sattar Ebrahimi Hassan Moghanian Mohammad Ali Bodaghi Fard Mehdi Kalhor 《Tetrahedron letters》2009,50(7):836-598
A series of new 1,2/1,3-bis[o-(N-methylidenamino-5-aryl-3-thiol-4H-1,2,4-triazole-4-yl)phenoxy]alkane derivatives 3a-d and bis[o-(N-methylidenamino-2-thiol-1,3,4-thiadiazole-5-yl)phenoxy]alkanes 6a-c were prepared by condensation of 4-amino-5-(aroyl)-4H-1,2,4-triazole-3-thiols 2a-b or 2-amino-5-mercapto-1,3,4-thiadiazole with bis-aldehydes 1a-c. Further reaction of compounds 3a-d and 6a-c with dibromoalkanes afforded the new macrocycles 5a-f and 8a-d. The cyclization does not require high dilution techniques and provides the expected azathia macrocycles in good yields, ranging from 55% to 68%. 相似文献
5.
Rachid Skouta 《Tetrahedron letters》2007,48(47):8343-8346
(±)-Pterocarpan and analogues (4a-c) have been synthesized efficiently via the annulation of salicylaldehydes (1a, 1b and 1c) and o-methoxymethoxylphenylacetylene (2a), followed by a one-pot reduction and acidic cyclization of the ketones (3a-c). In addition, isoflavone derivatives (5a-c) have been synthesized rapidly, in two steps, via the annulation of salicylaldehyde (1a) and arylacetylenes (2b, 2c and 2d), followed by IBX/DMSO oxidation of the isoflavanones (3d, 3e and 3f). 相似文献
6.
Shin-ichi Naya 《Tetrahedron》2005,61(36):8616-8624
The synthesis and properties of a novel type of 5-[bis(1-heteroazulen-3-yl)methylidene]pyrimidine-2,4,6(1,3,5H)-triones (13a-c) and (14a-c) are studied. The synthetic procedure is based on addition of bis(1-heteroazulen-3-yl)methyl cations with barbituric acid and subsequent oxidation by o-chloranil. Structural characteristics of 13a-c and 14a-c were clarified on inspection of the 13C NMR spectral data and X-ray crystal analysis. Based on the investigation of the UV-vis spectra of 13a-c and 14a-c and their protonated cations, conformational change of the heteroazulene-moiety and the barbituric acid-moiety is suggested. In the CV measurements of 13a-c and 14a-c, two reversible reduction waves are observed, indicating the stabilizing ability of heteroazulenes toward the corresponding radical and anion species. Furthermore, 13a-c and 14a-c exhibit one irreversible oxidation wave and the corresponding reduction wave appearing in a far negative region, which suggested a conformational change in the radical cation during the redox process. The conformational change is rationalized on the basis of the MO calculations. 相似文献
7.
Chih-Chin Chi 《Tetrahedron》2004,60(48):10869-10876
Refluxing an o-dichlorobenzene solution of 2,5-disubstituted thienosultines 10a-f with [60]fullerene for 2-24 h gave both 1:1 and 2:1 cycloadducts in 37-79% isolated yields. The reaction was highly accelerated by microwave irradiation giving comparable yields of cycloadducts. Sultines 10a-f underwent cheletropic extrusion of SO2 to form the corresponding non-Kekulé biradical intermediates 11a-f, which were subsequently trapped by [60]fullerene to form corresponding cycloadducts. The activation energy barriers (ΔGc≠) determined for the boat-to-boat inversion of these 4′,5′,6′,7′-tetrahydrobenzo[c]thieno-[5′,6′:1,2][60]fullerene adducts 12a-f were found to be in the range of 13.5-14.8 kcal/mol. Unexpectedly, one of the monoadduct 12a was found to be labile when kept in air under ambient light. Two new products 15 (a sulfine-enone) and 16 (an endione) were isolated from the decomposed 12a and were found to derive from self-sensitized singlet oxygen reaction on the 2,5-dimethylthieno moiety of 12a. 相似文献
8.
2,5-Dideuteriopyrazine (1-2,5-d2) and 2,6-dideuteriopyrazine (1-2,6-d2) phototranspose in the vapor phase to mixtures of 4,6-dideuteriopyrimidine (2-4,6-d2) and 2,5-dideuteriopyrimidine (2-2,5-d2) or 4,5-dideuteropyrimidine (2-4,5-d2) and 2,4-dideuteriopyrimidine (2-2,4-d2), respectively. In each case, a trace quantity of a dideuteriopyridazine (7-d2) photoproduct was also observed. These products are consistent with a diazaprefulvene mechanism involving, 2,6-bonding, one or two nitrogen migrations, and rearomatization. 相似文献
9.
Siriwan Sirinintasak 《Tetrahedron letters》2007,48(19):3433-3436
Syntheses of all-Z-tribenzo[12]annulenes (1a-c) and Z,Z-tribenzodidehydro[12]annulenes (2a-c) by the reduction of the corresponding tribenzohexadehydro[12]annulenes 3a-c were carried out using a low valent titanium complex generated from Ti(O-i-Pr)4 and i-PrMgCl. The unique structure of the first reduction products 2a-c as well as 1a-c was fully characterized. Complexation of these annulenes with silver(I) ions produces the corresponding silver complexes. Among them, the silver complexes of 2a-c exhibit interesting monomer-dimer equilibrium. 相似文献
10.
A convenient method for the preparation of benzofuro[3,2-c]isoquinoline derivatives is described. The condensation reaction of methyl 2-(chloromethyl)-benzoate with substituted salicylonitriles 7a-c and intramolecular cyclization of the resulting substituted methyl 2-[(2-cyanobenzyl)oxy]benzoates 10a-c using potassium tert-butoxide results in the substituted benzofuro[3,2-c]isoquinolin-5(6H)-ones 1a-c. The same sequence of reactions starting from 2-(chloromethyl)benzonitrile and compounds 7a-c gave substituted 5-aminobenzofuro[3,2-c]isoquinolines 13a-c. In addition, this method is useful for the synthesis of other heterocycles. For example, using 1-cyano-2-naphthol 16, instead of the salicylonitriles 7a-c, gives naphtho[1′,2′:4,5]furo[3,2-c]isoquinolines. 相似文献
11.
A simple four-step synthesis of 4-(2-aminoethyl)-5-hydroxy-1H-pyrazoles 8 (or their 1H-pyrazol-3(2H)-one tautomers 8′) as the pyrazole analogues of histamine was developed. First, enamino lactam 3 was prepared as the key intermediate in two steps from 2-pyrrolidinone (1). Next, acid-catalysed ‘ring switching’ transformations of 3 with monosubstituted hydrazines 4 gave N-[(1-substituted 5-hydroxy-1H-pyrazol-4-yl)ethyl]benzamides 7a-k and N-[2-(2-heteroaryl-3-oxo-2,3-dihydro-1H-pyrazol-4-yl)ethyl]benzamides 7′l-o. Benzamides 7a-k and 7′l-o were finally hydrolysed by heating in 6 M hydrochloric acid to furnish 1-substituted 4-(2-aminoethyl)-5-hydroxy-1H-pyrazoles 8a-k and 4-(2-aminoethyl)-2-heteroaryl-1H-pyrazol-3(2H)-ones 8′l-o in good overall yields. 相似文献
12.
To synthesize (3′R,5′S)-3′-hydroxycotinine [(+)-1], the main metabolite of nicotine (2), cycloaddition of C-(3-pyridyl)nitrones 3a, 3c, and 15 with (2R)- and (2S)-N-(acryloyl)bornane-10,2-sultam [(2R)- and (2S)-8] was examined. Among them, l-gulose-derived nitrone 15 underwent stereoselective cycloaddition with (2S)-8 to afford cycloadduct 16, which was elaborated to (+)-1. 相似文献
13.
Sukanta KamilaEdward R. Biehl 《Tetrahedron letters》2012,53(31):3998-4003
(5Z,5′Z)-3,3′-(1,4-Phenylenebis(methylene)-bis-(5-arylidene-2-thioxothiazolidin-4-one) derivatives (5a-r) have been synthesized by the condensation reaction of 3,3′-(1,4- or 1,3-phenylenebis(methylene))bis(2-thioxothiazolidin-4-ones) (3a,b) with suitably substituted aldehydes (4a-f) or 2-(1H-indol-3-yl)2-oxoacetaldehydes (8a-c) under microwave conditions. The bis(2-thioxothiazolidin-4-ones) were prepared from the corresponding primary alkyl amines (1a,b) and di-(carboxymethyl)-trithiocarbonyl (2). The 2-(1H-indol-3-yl)-2-oxoacetaldehydes (8a-c) were synthesized from the corresponding acid chlorides (7a-c) using HSnBu3. 相似文献
14.
Vijendra Kumar Fulwa 《Tetrahedron letters》2009,50(46):6264-182
Heating a neat 1:2 mixture of 2-picolylamine and 2-cyanopyridine followed by treatment of the resultant red gummy substance with aqueous KOH resulted in the isolation of 2,4,5-tris(2-pyridyl)imidazole (1a) as the major product and N-(3-(2-pyridyl)imidazo[1,5-a]pyridine)picolinamidine (2a) in small amounts. Similarly, by using 3-picolylamine, 2,4,-bis(2-pyridyl)-5-(3-pyridyl)imidazole (1b) and N-(3-(3-pyridyl)imidazo[1,5-a]pyridine)picolinamidine (2b) were isolated, and by using 4-picolylamine, 2,4,-bis(2-pyridyl)-5-(4-pyridyl)imidazole (1c) and N-(3-(4-pyridyl)imidazo[1,5-a]pyridine)picolinamidine (2c) were isolated. The plausible mechanism of the formation of 1a-c and 2a-c is delineated. 相似文献
15.
Yeong-Jiunn JangWen-Wei Lin Yuh-Kuo ShihJu-Tsung Liu Ming-Hsing HwangChing-Fa Yao 《Tetrahedron》2003,59(27):4979-4992
The reactions of ketones 1a-o, nitromethane 2, and a stoichiometric amount of piperidine 3a or ethylenediamine 3b in the presence of mercaptan 6a in THF or CH3CN solution give high yields of β-nitrosulfides 7a-o. The latter can be oxidized by 8a (m-CPBA or m-CPBA/AcOH) at 0°C, 8b (H2O2/AcOH), or 8c (H2O2) at room temperature, thus generating β-nitroalkylsulfoxides 9a-o, which then undergo elimination to produce medium to high yields of 2,2-disubstituted-1-nitroalkenes 5a-o, when refluxed in a solution of ClCH2CH2Cl (1,2-dichloroethane). After preparation from 1a-o, 2, 3, and 6a, 7a-o were oxidized with 8a, 8b, or 8c in a mixture of CH3CN and ClCH2CH2Cl to generate β-nitrosulfoxides 9a-o, which then underwent elimination under refluxing under one-pot conditions. Compounds 14 and 15g were also prepared using 13, 2, 3b, and 6, in a similar manner. 相似文献
16.
Chiral conjugated polymers P-1 and P-2 were synthesized by the polymerization of (R)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthalene ((R)-M-1) and (S)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthalene ((S)-M-1) with 2,5-bis(4-vinylphenyl)-1,3,4-oxadiazole (M-2) under Pd-catalyzed Heck coupling reaction, respectively. Both monomers and polymers were analysed by NMR, MS, FT-IR, UV, DSC-TG, fluorescent spectroscopy, GPC and CD spectra. The chiral conjugated polymers exhibit strong Cotton effect in their circular dichroism (CD) spectra indicating a high rigidity of polymer backbone. CD spectra of polymers P-1 and P-2 are almost identical and have opposite signs for their position. These polymers have strong blue fluorescence. 相似文献
17.
Shuji Yasuike Yoshihito Kishi Kentaro Yamaguchi 《Journal of organometallic chemistry》2006,691(10):2213-2220
Sb-chirogenic organoantimony compounds (±)-5a-c bearing heteroatom moieties such as 4,4-dimethyl-2-oxazolinyl, methoxymethyl, and diphenylphosphanyl substituents on the o-position of an aryl group have been prepared by nucleophilic displacement of the ethynyl moiety on (1-naphthyl)(phenylethynyl)(p-tolyl)stibane (3) with aryllithium reagents (2a-c). The optical resolution of the racemic (±)-5a,b was attained via separation of a diastereomeric mixture of their palladium complexes (S)-7 formed from the reactions of (±)-5a,b with di-μ-chlorobis[(S)-dimethyl(1-ethyl-α-naphthyl)aminato-C2,N]dipalladium(II) (6). The enantiomerically pure Sb-chirogenic stibanes isolated here were optically stable, and no racemization on the chiral antimony center was observed even when they were allowed to stand at room temperature for over 72 h in chloroform. The structure of 5a,b including the absolute configuration was determined by single crystal X-ray analyses of (+)-5aB and antimony-palladium complex (7bB), respectively. The analyses also revealed the presence of intramolecular interaction between the antimony and sp2-nitrogen atoms in the molecule Sb(S)-(+)-5aB. 相似文献
18.
1-Benzyl-3-(bromomethyl)-2(1H)-pyrazinone was converted to [3,4-c] sulfolene pyridinone 8a and further (1- or 3-) substituted derivatives having a dienophilic side chain on the sulfolene ring. Thermolytic extrusion of sulfur dioxide from o-QDM precursor 8 led to generation of 3,4-dimethylene-2(1H)-pyrazinone 9, which was reacted in situ with various dienophiles. Thermolysis of the substituted precursors resulted in intramolecular cycloaddition of the corresponding o-QDM intermediates 相似文献
19.
The reaction of 2-(diphenylmethylene)thietan-3-one (2) with 1,2,4,5-tetrazines (3a-c) in KOH/MeOH/THF gives 4H-pyrazolo[5,1-c]thiazines (7a-c). This novel condensation reaction proceeds via the intermediacy of an 8-(diphenylmethylene)-2H-1,4,5-thiadiazocin-7(8H)-one (5), which undergoes a multi-step rearrangement including a rare anti-Michael addition. 相似文献
20.
Jochen Niemeyer 《Journal of organometallic chemistry》2010,695(14):1801-2052
Condensation of the O-protected hydroxyferrocene carbaldehyde (Sp)-1 with suitable diamines, followed by liberation of the hydroxyferrocene moiety leads to a new type of ferrocene-based salen ligands (3). While the use of ethylenediamine in the condensation reaction yields the planar-chiral ethylene-bridged ligand [(Sp,Sp)-3a], reaction with the enantiomers of trans-1,2-cyclohexylendiamine gives rise to the corresponding diastereomeric cyclohexylene-bridged systems [(S,S,Sp,Sp)-3b and (R,R,Sp,Sp)-3c], which feature a combination of a planar-chiral ferrocene unit with a centrochiral diamine backbone. Starting with the ferrocene-aldehyde derivative (Rp)-1, the enantiomeric ligand series (3d/e/f) is accessible via the same synthetic route.The (Sp)-series of these newly developed N2O2-type ligands was used for the construction of the corresponding mononuclear bis(isopropoxy)titanium (4a/b/c), methylaluminum (5a/b/c) and chloroaluminum-complexes (6a/b/c), which were isolated in good yields and identified by X-ray diffraction in several cases. The aluminum complexes (5/6) were successfully used in the Lewis-acid catalyzed addition of trimethylsilylcyanide to benzaldehyde, yielding the corresponding cyanohydrins in 45-62% enantiomeric excess. 相似文献