Regioselective Cycloadditions of Phosphonyl Nitrile Oxides with Vinylphosphonate and Phosphaalkyne

1,3-Dipolar cycloaddition reactions are important synthetic manipulations allowing the construction of five-membered heterocycles. In this article, we report the cycloaddition of phosphonyl nitrile oxides with vinylphosphonate and phosphaalkyne to form the unexpected 2:1 cycloaddition product with excellent levels of regiocontrol product. The structures of title compounds were confirmed by ¹H NMR, ³¹P NMR, MS, and IR. The mechanism of the cycloaddition was explored using the density functional theory (DFT) method.     

Synthesis of new polyhedral oligomeric silsesquioxane derivatives as some possible antimicrobial agents

1,3-Dipolar cycloaddition reactions were studied to synthesize Polyhedral oligomeric silsesquioxane (POSS)-based norbornyl imide derivatives containing izoxazoline groups in good yields. And also 1,3-dipolar cycloaddition reactions of azomethine ylides with POSS-based norbornene dipolarophiles for a synthesis of the novel POSS-based norbornane-fused spiro-1,3-indandionolylpyrrolidines are reported. All newly synthesized POSS compounds were structurally characterized by FTIR, ¹H, ¹³C NMR, HRMS and GC/MS analyses.     

Intramolecular cycloaddition of fluorinated 1,3,4-oxadiazoles to dienes

Cycloaddition reactions of fluorinated 1,3,4-oxadiazoles with conjugated and unconjugated dienes was studied. The reactions resulted in the formation of products of double cycloaddition (7-oxabicycloheptane type compounds), along with products of intramolecular cycloaddition (oxatricyclic and oxatetracyclic compounds). The structure of 4-(trifluoromethyl)-2-ethoxycarbonyl-1,6-dimethyl-3-oxatricyclo[2.2.1.0^2,6]heptane was confirmed by single crystal X-ray diffraction analysis.     

Heterocyclic synthesis using nitrilimines: Part 19. Synthesis of novel 1,3,5-trisubstituted-1,2,4-triazoles

This paper describes the synthesis of a new series of 1,3,5-trisubstituted-1,2,4-triazoles by 1,3-dipolar cycloaddition reaction of C-phenyl-aminocarbonyl-N-arylnitrilimines with guanidine derivatives. The structures of the newly synthesized compounds were elucidated by spectral methods (IR, ¹H NMR, ¹³C NMR and MS spectroscopy) and elemental analysis. The microbial features of the synthesized compounds were studied using well-established methods from the literature.     

Synthesis,structural characterization,and anion interactions of new triazole-linked urea derivative fully substituted cyclotriphosphazene compounds

Three novel fully substituted urea derivative cyclotriphosphazene compounds 5–7 were synthesized by alkyne-azide 1,3-dipolar cycloaddition reaction of propargyl substituted ureas 2–4 with hexaazide substituted cyclotriphosphazene 1 in the presence of Cu(I) catalyst. All compounds were characterized with spectroscopic techniques such as FT-IR, ¹H, ¹³C, and ³¹P nuclear magnetic resonance and mass spectroscopy. Also, the usefulness of compounds 5–7 as anion carriers was investigated by ¹H NMR spectroscopy. For this purpose, ¹H NMR spectra of compounds 5–7 were recorded in the presence of tetrabutylammonium fluoride in DMSO-d₆. It was determined, that the urea protons in the compounds interact with fluoride.     

Synthesis of isoxazolidines by 1,3-dipolar cycloaddition and their bioactivity

A series of new isoxazolidines was prepared by 1,3-dipolar cycloaddition of different mono-substituted styrenes with 1,3-dipolar compounds that were prepared by the reaction of N-methylhydroxylamine sulfate with aromatic carbonyl substances. This synthetic pathway for the preparation of isoxazolidines was an ideal process of green chemistry. The synthetic products were 5-substituted isoxazolidines and their structures were characterized by mass and NMR (¹H-, ¹³C-, COSY, HSQC, and DEPT) spectrometry, and their bioactivity was investigated indicating that some new compounds inhibited Botrytis cinerea effectively. __________ Translated from Chinese Journal of Organic Chemistry, 2005, 25(11) (in Chinese)     

Design,synthesis and application of new bile acid ligands with 1,2,3-triazole ring

New dimers have been obtained from propargyl ester of bile acids and α,α′-diazide-m-xylene by intermolecular 1,3-dipolar cycloaddition. These compounds have been used as ligands to form intermolecular hydrogen bonds with various aromatic acids. The structures of all products were confirmed by spectroscopic (¹H NMR, ¹³C NMR and FT-IR) analysis, mass spectrometry (ESI, MALDI) and PM5 semiempirical methods.     

The configuration and conformation of the tricyclo[4.4.1.12,5]dodecan-11-ols determined by 1H NMR spectroscopy using the shift reagent Eu(fod)3

The isomeric tricyclo[4.4.1.1^2,5]dodecan-11-ols have been synthesized from the (6+4) cycloaddition product of tropone with cyclopentadiene. The configuration and conformation of each isomer was determined from the proton shift gradients induced in the olefinic proton signals in the ¹H NMR spectra of intermediate compounds by Eu(fod)₃.     

Synthesis of Heterocyclic Pentavalent Phosphorus Compounds from Phosphite Derivatives and Indane-1,2,3-Trione

Reaction of trialkylphosphite derivatives with indane-1,2,3-trione proceeds smoothly at room temperature to afford the corresponding heterocyclic pentavalent [P(V)] phosphorus compounds via an intermolecular [4+1] cycloaddition reaction in excellent yields under solvent-free conditions. We also used dimethylphosphite and diethylphosphite instead of trialkylphosphites in this reaction, but the corresponding pentavalent phosphorus compounds were not isolated, and in both cases phosphate derivatives were obtained. The structures of the products were deduced from their IR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectra, and mass spectrometry.     

Synthesis,antioxidant activity,and α-glucosidase enzyme inhibition of α-aminophosphonate derivatives bearing piperazine-1,2,3-triazole moiety

A novel series of piperazine-1,2,3-triazole bearing dimethyl(((2-(4-((1H-1,2,3-triazole-4-yl)methyl)piperazin-1-yl)ethylamino)(2-hydroxyaryl)methyl)phosphonate derivatives have been prepared via copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) (Click Reaction) and Schiff base reactions. The synthesized compounds were confirmed by spectral characterization (¹H, ¹³C and ³¹P NMR, and mass). The title compounds were evaluated for in vitro alpha glucosidase enzyme inhibition and in vitro antioxidant activity using DPPH and H₂O₂ methods.     

The Regiospecific Synthesis of Some New 3,5‐Disubstituted Isoxazoles

The compounds with isoxazole moiety have many pharmacological, biological and industrial applications, specifically their antiviral activity. In this research work, seven new compounds of 3,5‐disubstituted isoxazoles were synthesized. Propargyl alcohol ( 1 ) reacted with benzoyl chloride to give propargylphenylcarboxylate ( 2 ). Then, the aldehydes ( 3a‐3g ) were converted to the related oximes ( 4a‐4g ) and nitrileoxides in situ by NaOCl, consequently. Reaction of compound 2 with nitrileoxides in a [3+2] cycloaddition reaction gave regiospecifically isoxazoles ( 5a‐5g ). ¹H NMR, ¹³C NMR, FT‐IR, and elemental analyses confirmed the structure of the synthesized compounds.     

1,3‐Dipolar cycloaddition reaction: Synthesis of novel 5,6‐dehydronorcantharidin derivatives of substituted aromatic amines with potential antitumor activities

Twelve novel compounds were synthesized by the [3+2] 1,3‐dipolar cycloaddition reaction of 5,6‐dehydronorcantharidin derivatives of substituted aromatic amines with nitrile oxides. The structure and the configuration of all compounds were confirmed by ¹H NMR, IR, MS, ¹H‐¹HCOSY, and NOESY spectral data. Their anti‐tumor activities are under way.     

Synthesis and Antimicrobial Evaluation of New Monocyclic β‐Lactams

A simple, practical, and efficient approach to synthesize new series of 2‐(3‐(2,4‐dichlorophenoxy)‐2‐(4‐(dimethylamino)phenyl)‐4‐oxoazetidin‐1‐ylamino)‐N‐arylacetamide by Staudinger [2 + 2] cycloaddition reaction. The titled compounds were evaluated for their antibacterial and antifungal activity against eight microorganisms. All the newly synthesized compounds are characterized by IR, ¹H‐NMR, and mass spectroscopic data.     

Synthesis of condensed pregnano[17,16-<Emphasis Type="Italic">d</Emphasis>]triazolines under high pressure

Condensed pregnano[17,16-d]triazolines were produced in 1,3-dipolar cycloaddition of 16-dehydropregnenolone acetate with organic azides at 10 kbar. The structure of the synthesized compounds was determined by using two-dimensional NMR spectroscopy (¹H—¹H COSY, NOESY, HSQC, and HMBC).     

Design,Synthesis, and Biological Activities of Novel 2‐Alkylpyrrole Derivatives

To investigate the alkyl analog of insecticide chlorfenapyr, two series of 2‐alkyl‐4‐bromo‐5‐(trifluoromethyl)pyrrole‐3‐carbonitriles were synthesized with a cycloaddition as the key step. The target products were characterized by ¹H‐NMR spectroscopy, elemental analysis, or HRMS. The insecticidal, herbicidal, and antifungal activities of the target compounds were evaluated and found that these compounds did not show much insecticidal activity, but compounds 4 , 10 , and 11 had very good fungicidal activities against Alternaria solani and Fusarium oxysporum. Moreover, compound 4 had an outstanding inhibition effect against pigweed.     

Design and Synthesis of Novel 2‐(1,2,4‐triazol‐1‐yl)‐quinoline‐Based Tricyclic 1,5‐benzothiazepine Derivatives

A series of new tricyclic 1,5‐benzothiazepine derivatives containing 2‐(1,2,4‐triazol‐1‐yl)quinoline were synthesized by the reaction of 1,5‐benzothiazepine with benzohydroximinoyl chlorides via 1,3‐dipolar cycloaddition reaction. The structures of the target compounds were confirmed by IR, ¹H NMR, MS, elemental, and X‐ray crystallographic analysis.     

异噁唑基取代的1,2,4-噁二唑啉和吡唑啉类化合物的合成

通过3-乙酰基-5-羟甲基异噁唑衍生的Schiff碱2与由醛肟原位生成的腈氧化物的1,3-偶极环加成反应, “一锅法”制备了5-甲基-5-[5-(叔丁基二甲基硅氧基甲基)-3-异噁唑基]-3-芳基-4-(4-甲氧基苯基)-4,5二氢-1,2,4-噁二唑类化合物4a～4e; 同时由3-乙酰基-5-羟甲基异噁唑衍生的α,β-不饱和酮(5)与取代苯肼的环化反应制备了5-(叔丁基二甲基硅氧基甲基)-3-[(1,5-二芳基)-3-(4,5-二氢吡唑基)]-异噁唑类化合物6a～6i. 所有新化合物的结构经核磁共振谱氢谱和碳谱、质谱、红外光谱以及高分辨质谱等进行了确证.     

Synthesis of Novel 1,2,4‐oxadiazoline Derivatives Containing Quinoline Moiety by 1,3‐Dipolar Cycloaddition

A series of novel 1,2,4‐oxadiazoline derivatives containing 2‐(1,2,4‐triazol‐1‐yl)quinoline were synthesized by the reaction of imines with benzohydroximinoyl chlorides in the presence of Et₃N via 1,3‐diplolar cycloaddition reaction. The structures of the target compounds were confirmed by IR, ¹H NMR, MS, elemental, and X‐ray crystallographic analysis.     

Anti- and syn-Tricyclo [4.2.1.12,5]decane. Preliminary communication

The two novel tricyclic C₁₀H₁₆ compounds anti- and syn-tricyclo [4.2.1.1^2,5]- decane ( 16 and 17 , respectively) were synthesized starting either from the photodimer 2 (anti) or the two cycloaddition products 8 (anti) and 9 (syn).     

Electron transfer activation of the Diels-Alder reaction: Quantitative relationship to charge transfer excited states

The Diels-Alder cycloaddition of anthracene to tetracyanoethylene (TCNE) is quantitatively compared to alkylmetal insertion under the same reaction conditions. In both systems, the observation of transient charge transfer (CT) absorption bands is related to the presence of 1:1 electron donor-acceptor complexes of anthracene (Ar) and alkylmetal (RM) donors with the TCNE acceptor. The activation free energies ΔG3 for anthracene cycloaddition and alkylmetal insertion are found to be equal to the energies of ion-pair formation, i.e. [Ar⁺TCNE^?] and RM⁺TCNE^?], which are evaluated from the CT transition energies hν_CT. Indeed, the differences in the rates of alkylmetal insertion and anthracene cycloaddition by a factor of more than 10⁹, are shown quantitatively to arise from the differences in ion-pair solvation ΔG^s. The same differences in ΔG^s also apply quantitatively to the free ions, [Ar⁺] and [RM⁺], independently derived from the electrochemical and iron(III) oxidations of alkylmetals and aromatic compounds, respectively, by outer- sphere electron transfer. The charge transfer formulation of the activation process but provides a unifying basis for comparing such diverse processes as Diels-Alder cycloadditions and organometal cleavages, when a common electron-deficient acceptor is employed. The relationship to the concerted mechanisms of the Diels-Alder reaction is discussed.