An efficient and divergent one‐pot synthesis of substituted 2H‐pyrans, 4H‐pyrans and pyridin‐2(1H)‐ones from β‐oxo amides based on the selection of the reaction conditions is reported. Mediated by N,N,N′,N′‐tetramethylchloroformamidinium chloride, β‐oxo amides underwent intermolecular cyclizations in the presence of triethylamine at room temperature to give substituted 2H‐pyrans in high yields, which could be converted into substituted 4H‐pyrans in the presence of sodium hydroxide in ethanol at room temperature, or into substituted pyridin‐2(1 H)‐ones under reflux. 相似文献
A novel palladium‐catalyzed intramolecular tandem annulation method is presented for the synthesis of 3‐[5H‐dibenzo[b,e]azepin‐11(6H)‐ylidene]indolin‐2‐ones. This method allows the conversion of various 3‐[2‐(2‐iodobenzylamino)aryl]‐N‐arylpropiolamides to the corresponding 3‐[5H‐dibenzo[b,e]azepin‐11(6H)‐ylidene]indolin‐2‐ones through the diarylation of an alkyne. 相似文献
A novel method that involves intramolecular annulation and a new type of rearrangement has been developed for the synthesis of 4‐aryl‐2(5H)‐furanones. A variety of prop‐2‐ynyl 3‐oxo‐3‐phenylpropanoates undergo annulation cyclization in the presence of chloro(triphenylphosphine)gold and trifluoromethanesulfonic to afford the desired products in moderate to high yields. 相似文献
Catalytic asymmetric conjugate arylation of racemic 6‐substituted cyclohexenones with arylboronic acids was catalyzed by 3 mol % of chiral amidophosphane‐[RhCl(C2H4)]2 in a 10:1 mixture of 1,4‐dioxane and water at 70 °C to afford a nearly 1:1 mixture of trans‐ and cis‐5‐aryl‐2‐substituted cyclohexanones in high enantioselectivity, which was subsequently epimerized with sodium ethoxide in ethanol to give thermodynamically stable trans‐5‐aryl‐2‐substituted cyclohexanones with 99–97 % ee in high two‐step yields. 相似文献
A series of 20 5‐amino‐1‐aryl‐1H‐tetrazoles was synthesized by diazotation of corresponding 1‐amino‐3‐aryl‐guanidines and tested for growth‐inhibiting activity against autotrophic Chlorella vulgaris cultures. In the used tests the different algae growth was quantified by photometric measurements at 680 nm. From obtained dosage‐effectivity relationships the reciprocal values of isoeffective concentrations c 50 were derived and defined as activity parameters A in QSAR (quantitative structure‐activity relationship) studies. It could be shown that the algistatitic activity (log A) of the tested heterocycles strongly depends on hydrophobicity described by their octan‐1‐ol/water partition coefficients (log P). The calculated linear relationships between log A and log P can be significantly improved by separate treatment of meta‐/para‐ and ortho‐substituted compounds or using an indicator variable to describe the lower activity of ortho‐substituted 5‐ami‐no‐1‐aryl‐1H‐tetrazoles in common regression equations. The results are discussed and compared with analogous QSAR found for earlier tested series of N‐heterocycles and compounds with urea structure. 相似文献
A highly enantioselective Michael addition of 3‐substituted benzofuran‐2(3H)‐ones to chalcones catalyzed by a chiral bifunctional thiourea was developed. Several chiral 3,3′‐substituted benzofuran‐2(3H)‐ones derivatives, bearing adjacent quaternary‐tertiary stereocenters, were efficiently synthesized with excellent enantioselectivities. 相似文献
The three‐component reaction of aryl halides, sodium sulfide pentahydrate (Na2S⋅5 H2O), and propiolic acid in the presence of 2.5% bis(triphenylphosphine)palladium chloride [Pd(PPh3)2Cl2], 5% 1,4‐bis(diphenylphosphino)butane (dppb) and 2 equivalents of 1,8‐diazabicycloundec‐7‐ene (DBU) produces stereoselectively (Z)‐3‐arylthioacrylic acids in good yields. A study of the reaction pathway suggested that the C S bond formation between aryl halides and Na2S⋅5 H2O proceeded first, and the resulting intermediate reacted with propiolic acid to produce the desired product. In addition, when the resulting product was treated with acid, the respective thiochromenones were formed in good yields. 相似文献
Previous studies by our research group have been concerned with the design of selective inhibitors of heme oxygenases (HO‐1 and HO‐2). The majority of these were based on a four‐carbon linkage of an azole, usually an imidazole, and an aromatic moiety. In the present study, we designed and synthesized a series of inhibition candidates containing a shorter linkage between these groups, specifically, a series of 1‐aryl‐2‐(1H‐imidazol‐1‐yl/1H‐1,2,4‐triazol‐1‐yl)ethanones and their derivatives. As regards HO‐1 inhibition, the aromatic moieties yielding best results were found to be halogen‐substituted residues such as 3‐bromophenyl, 4‐bromophenyl, and 3,4‐dichlorophenyl, or hydrocarbon residues such as 2‐naphthyl, 4‐biphenyl, 4‐benzylphenyl, and 4‐(2‐phenethyl)phenyl. Among the imidazole‐ketones, five ( 36 – 39 , and 44 ) were found to be very potent (IC50<5 μM ) toward both isozymes. Relative to the imidazole‐ketones, the series of corresponding triazole‐ketones showed four compounds ( 54 , 55 , 61 , and 62 ) having a selectivity index >50 in favor of HO‐1. In the case of the azole‐dioxolanes, two of them ( 80 and 85 ), each possessing a 2‐naphthyl moiety, were found to be particularly potent and selective HO‐1 inhibitors. Three non‐carbonyl analogues ( 87 , 89 , and 91 ) of 1‐(4‐chlorophenyl)‐2‐(1H‐imidazol‐1‐yl)ethanone were found to be good inhibitors of HO‐1. For the first time in our studies, two azole‐based inhibitors ( 37 and 39 ) were found to exhibit a modest selectivity index in favor of HO‐2. The present study has revealed additional candidates based on inhibition of heme oxygenases for potentially useful pharmacological and therapeutic applications.相似文献
An efficient method has been developed for the one‐pot copper(I)‐catalyzed synthesis of 3‐aminocoumarin and its derivatives, such as 3‐substituted methylideneaminocoumarins and chromeno[3,4‐d]imidazol‐4(1H)‐ones. Significantly, the strategy presents a straightforward and efficient approach to constructing biologically useful molecular scaffolds. 相似文献
The reaction of primary 2,3‐allenols with iodine (I2) afforded 2,5‐dihydrofurans while that of readily available 1‐aryl or 1‐methyl substituted 2,3‐allenols with bromine (Br2), N‐bromosuccinimide (NBS), I2 or N‐iodosuccinimide (NIS) formed the not easily available but synthetically useful 3‐halo‐3‐alkenals and 2‐halo‐2‐alkenyl ketones with good selectivity and yields via a sequential electrophilic interaction of X+ with the allene moiety, 1,2‐aryl or 1,2‐proton shift, and H+ elimination process. 相似文献
tert‐Butyl isocyanide ( 2 ) reacts with acceptor‐substituted nitrile imines to give derivatives of tetrahydro‐1,2,5,6‐tetrazocines 3 along with substituted 5‐hydrazonoyl‐1,2,4‐triazoles 4 . Replacement of 2 with aryl or sec‐alkyl isocyanides leads to substituted a‐hydrazonoamides ( 6B ) rather than to analogues of 3 ; removal of the acceptor group in 1 is likewise detrimental. — The structure of 3 has been established by means of an X‐ray diffraction analysis of 3d . 相似文献
A novel palladium‐catalyzed approach to direct C‐3‐arylation of 1H‐indoles with arylhydrazines using air as the oxidant via C N bond cleavage has been developed. Various substituents are tolerated in this system in moderate to good yields. This reaction could also be compatible with a larger scale. Thus, this strategy using arylhydrazines as arylating reagents provides a powerful method for constructing substituted 3‐aryl‐1H‐indoles. 相似文献
A highly effective aldol cyclization of α‐isothiocyanato imide to both β,γ‐unsaturated α‐keto esters and aryl‐substituted α‐keto esters has been developed. A chiral N,N′‐dioxide–yttrium triflate complex was used as the catalyst. A series of cyclic thiocarbamates bearing chiral quaternary stereocenters was synthesized in good to high yields, excellent diastereo‐ (up to 25:1 dr) and enantioselectivities (up to 99 % ee). In addition, the reaction could be carried out on a gram‐scale, and other functionalized derivatives are also conveniently transformed. Interestingly, a discrepancy of diastereoselection was observed between the reactions of β,γ‐unsaturated α‐keto esters and aryl‐substituted α‐keto esters. Moreover, a substrate dependency of non‐linear effects was observed in this reaction. On the basis of the experimental results and the absolute configuration of the products, possible catalytic models have been proposed to explain the origin of the asymmetric process.
An effective synthesis of structurally diverse pyrroline derivatives has been accomplished by a gold(I)‐catalyzed tandem 1,3‐acyloxy rearrangement/intramolecular azacylization reaction of γ‐amino‐substituted propargylic esters in good to excellent chemical yields (52–98%). The reaction proceeds under extremely mild conditions and has also demonstrated its potential in a concise formal synthesis of (±)‐aphanorphine with a catalyst loading as low as 0.5 mol% to provide the key intermediate 5‐(4‐methoxybenzyl)‐1‐tosyl‐2,5‐dihydro‐1H‐pyrrol‐3‐yl pivalate on a gram scale.
A series of bioisosteric N1‐ and N2‐substituted 5‐(piperidin‐4‐yl)‐3‐hydroxypyrazole analogues of the partial GABAAR agonists 4‐PIOL and 4‐PHP have been designed, synthesized, and characterized pharmacologically. The unsubstituted 3‐hydroxypyrazole analogue of 4‐PIOL ( 2 a ; IC50~300 μM ) is a weak antagonist at the α1β2γ2 GABAAR, whereas substituting the N1‐ or N2‐position with alkyl or aryl substituents resulted in antagonists with binding affinities in the high nanomolar to low micromolar range at native rat GABAARs. Docking studies using a α1β2γ2 GABAAR homology model along with the obtained SAR indicate that the N1‐substituted analogues of 4‐PIOL and 4‐PHP, 2 a – k , and previously reported 3‐substituted 4‐PHP analogues share a common binding mode to the orthosteric binding site in the receptor. Interestingly, the core scaffold of the N2‐substituted analogues of 4‐PIOL and 4‐PHP, 3 b – k , are suggested to flip 180° thereby adapting to the binding pocket and addressing a cavity situated above the core scaffold. 相似文献
A library of 5‐methylindolo[3,2‐c]quinolones (IQc) with various substitution patterns of alkyldiamine side chains were evaluated for G‐quadruplex (G4) binding mode and efficiency. Fluorescence resonance energy transfer melting assays showed that IQcs with a positive charge in the heteroaromatic nucleus and two weakly basic side chains are potent and selective human telomeric (HT) and gene promoter G4 stabilizers. Spectroscopic studies with HT G4 as a model showed that an IQc stabilizing complex involves the binding of two IQc molecules (2,9‐bis{[3‐(diethylamino)propyl]amino}‐5‐methyl‐11H‐indolo[3,2‐c]quinolin‐5‐ium chloride, 3 d ) per G4 unit, in two non‐independent but equivalent binding sites. Molecular dynamics studies suggest that end‐stacking of 3 d induces a conformational rearrangement in the G4 structure, driving the binding of a second 3 d ligand to a G4 groove. Modeling studies also suggest that 3 d , with two three‐carbon side chains, has the appropriate geometry to participate in direct or water‐mediated hydrogen bonding to the phosphate backbone and/or G4 loops, assisted by the terminal nitrogen atoms of the side chains. Additionally, antiproliferative studies showed that IQc compounds 2 d (2‐{[3‐(diethylamino)propyl]amino}‐5‐methyl‐11H‐indolo[3,2‐c]quinolin‐5‐ium chloride) and 3 d are 7‐ to 12‐fold more selective for human malignant cell lines than for nonmalignant fibroblasts. 相似文献
Visible light irradiation of N‐bromosuccinimide serves as an effective means to convert methyl 2‐(azidomethyl)‐3‐arylpropenoates and 2‐(azidomethyl)‐3‐arylacrylonitriles to the corresponding iminyl radicals via α‐hydrogen abstraction and subsequent extrusion of dinitrogen. Thus formed iminyl radicals then undergo intramolecular ortho attack on the aryl ring, affording methyl quinoline‐3‐carboxylates and quinoline‐3‐carbonitriles respectively.
The synthesis of tetrahydro‐2,1‐benzisothiazolium salts 8 and cyclohepta[c] isothiazolium salts 11 by ring transformation of bicyclic isothiazolium perchlorates 2 , 3 is described and the by‐products 9 , 10 and 12 are characterized. Oxidation of the bicyclic salts 8 and 11 results in a new route to obtain ω‐(2‐aryl‐1,1,3‐trioxo‐2,3‐dihydro‐1H‐isothiazol‐4‐yl)‐alkanoic acids 17 and 18 by Criegee‐type‐rearrangement. 相似文献