Cycloaddition Of Diazo Compounds Research Articles

Copper‐Catalyzed Chemo‐ and Diastereoselective 1,3‐Dipolar Cycloaddition of Carbonyl Ylide and Aldehyde‐Tethered‐Cyclohexadienone to Access Polycyclic Systems

AbstractA copper‐catalyzed tandem intermolecular ylide formation/intramolecular cycloaddition of diazo compounds and aldehyde‐tethered‐cyclohexadienones was reported, chemo‐ and diastereoselectively providing oxapolycyclic frameworks in moderate to excellent yields under mild conditions. This reaction creates two C−C bonds and one C−O bond with five stereocentres including two all‐carbon quaternary centres. Moreover, the late‐stage diversification of products can be realized via chemoselective substitutions.magnified image

Highly Regioselective Synthesis of 3,5-Substituted Pyrazoles from Bromovinyl Acetals and N-Tosylhydrazones

A regioselective synthesis of 3,5-disubstituted pyrazoles was achieved by 1,3-dipolar cycloaddition of diazo compounds, generated in situ from N-tosylhydrazones, with unactivated bromovinyl acetals, which served as alkyne surrogates. The reaction tolerated N-tosylhydrazones bearing various substituted benzylidene groups, and a range of 3,5-disubstituted pyrazoles were obtained in yields of up to 92%.

Synthesis of Functionalized Pyrazoles via 1,3‐Dipolar Cycloaddition of α‐Diazo‐β‐ketophosphonates, Sufones and Esters with Electron‐Deficient Alkenes

1,3-Dipolar cycloaddition of diazo compounds with olefinic substrates is a promising atom-economic strategy for the construction of functionalized pyrazoles. Over the last few years, our group has been engaged in the synthesis of phosphonyl/sulfonylpyrazoles and pyrazole esters by employing Bestmann-Ohira Reagent (BOR) and its sulfur and ester analogs as 1,3-dipole precursors with various dipolarophiles. This account describes the novel synthetic methods developed in our laboratory, in the perspective of closely related work by others, for the synthesis of phosphonyl/sulfonylpyrazoles, pyrazole esters and the total synthesis of Withasomnine, a natural product, by using 1,3-dipolar cycloaddition as the key step.

Chemistry of Phosphorus Ylides. Part 40. Synthesis of Pyrazoles by the [3 + 2] Cycloaddition of Diazo Compounds with Wittig Reagents as Antimicrobial Compounds

A comparative study between the reactions of active phosphacumulenes and stabilized phosphonium ylides on some diazo compounds have been performed. A number of substituted phosphanylidene spiro pyrazoles have been synthesized from the reaction of the active phosphacumulenes and the diazo derivatives. On the other hand, treatment of the diazo substrates with the stabilized phosphonium ylides led to the formation of the corresponding ylidenes and diazenyl phosphanylidenes. The antimicrobial activities for the new compounds are also reported.

ChemInform Abstract: Synthesis of New Pyrazolines and Their Biological Evaluation as Antimicrobial Agents.

AbstractNovel pyrazolines (III) and (V) are prepared via 1,3‐dipolar cycloaddition of diazo compounds to alkynes (I).

An Efficient One-Pot Synthesis of 3,5-Diaryl-4-bromopyrazoles by 1,3-Dipolar Cycloaddition of In Situ Generated Diazo Compounds and 1-Bromoalk-1-ynes

A simple, highly efficient, one-pot synthesis of 3,5-di­aryl-4-bromopyrazoles via 1,3-dipolar cycloaddition of diazo compounds and alkynyl bromides has been developed. The diazo compounds and alkynyl bromides were generated in situ from tosylhydrazones and gem -dibromoalkenes, respectively. When ketone-derived hydrazones were used, 3,5-diaryl-4-bromo-3 H -pyrazoles were obtained and the isomerization products 3,5-diaryl-4-bromo-1 H -pyrazoles were formed when using aldehyde-derived hydrazones. The reaction system exhibited high regioselectivity and good functional group tolerance. Both electron-rich and electron-deficient­ substituents on the aromatic ring of the hydrazones or the gem -dibromoalkenes gave desired products in moderate to good yields (67–86%).

ChemInform Abstract: Synthesis of 2‐Aminofurans and 2‐Unsubstituted Furans via Carbenoid‐Mediated [3 + 2] Cycloaddition.

AbstractThe cycloaddition of diazo compounds (I) with enamines (II) followed by oxidation of intermediate 2‐amino‐2,3‐dihydrofurans leads to 2‐aminofurans (III), whilst the treatment of intermediates with TosOH gives rise to 2‐unsubstituted furans (IV).

Diastereoselective ruthenium porphyrin-catalyzed tandem nitrone formation/1,3-dipolar cycloaddition for isoxazolidines. Synthesis, in silico docking study and in vitro biological activities

Ruthenium porphyrin catalyzes tandem nitrone formation/1,3-dipolar cycloaddition of diazo compounds, nitrosoarenes and alkenes to form isoxazolidines in good to high yields and with excellent regio-, chemo- and diastereo-selectivities. A broad substrate scope of alkenes is applicable to this protocol and various functional groups are compatible with the reaction conditions. In silico analysis and in vitro biological experiments revealed that some of the new isoxazolidines synthesized in this work could act as leukotriene A4 hydrolase inhibitors.

Palladium-catalyzed selective cycloaddition of diazo compounds to [60]fullerene

The effective catalytic method for cycloaddition of higher diazoalkanes and diazoacetates to [60]fullerene in the presence of the three-component catalytic system Pd(acac)2–PPh3–Et3Al has been developed. The yield and selective formation of the target homo- and methanofullerenes are dependent upon the structure of the original diazo compounds.

ChemInform Abstract: Catalytic [2 + 1] Cycloaddition of Diazo Compounds to [60]Fullerene.

A catalytic method for the efficient synthesis of 5,6-open and 6,6-closed (2π+1π) fullerene adducts by [2+1] cycloaddition of ethyl 2-alkyl(hetaryl)-2-diazoacetates to [60]fullerene in the presence of a three-component catalyst Pd(acac)2—PPh3—Et3Al have been developed.

ChemInform Abstract: Synthesis of Indazoles by the [3 + 2] Cycloaddition of Diazo Compounds with Arynes and Subsequent Acyl Migration.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of Indazoles by the [3+2] Cycloaddition of Diazo Compounds with Arynes and Subsequent Acyl Migration

The [3+2] cycloaddition of a variety of diazo compounds with o-(trimethylsilyl)aryl triflates in the presence of CsF or TBAF at room temperature provides a very direct, efficient approach to a wide range of potentially biologically and pharmaceutically interesting substituted indazoles in good to excellent yields under mild reaction conditions. Simple diazomethane derivatives afford N-unsubstituted indazoles or 1-arylated indazoles, depending upon the stoichiometry of the reagents and the reaction conditions, while dicarbonyl-containing diazo compounds undergo carbonyl migration to afford 1-acyl or 1-alkoxycarbonyl indazoles selectively.

Microwave-Assisted Synthesis of Pyrazoles by 1,3-Dipolar Cycloaddition of Diazo Compounds to Acetylene Derivatives

Microwave-assisted preparation of a wide range of 5-ethoxycarbonylpyrazoles and 3-pyrazoles by 1, 3-dipolar cycloaddition of diazo compound to acetylenes is described. All reactions were carried out using high throughput sequential technique

Reactivity of heterophospholes toward 1,3‐dipolar cycloaddition of diazo compounds—an FMO analysis

AbstractThe molecular geometries and the frontier orbital energies of three diazo compounds [diazodiphenylmethane (2), the α‐silyl‐α‐diazoketone 3 and the isomeric 2‐siloxy‐1‐diazoalkene 4], 10 heterophospholes with a PC bond and two heterophospholes with a PN bond were obtained from DFT calculations at the B3LYP/6–311+G** level. The 1,3‐dipolar cycloaddition reactivity of diazo compounds 2–4 toward the heterophospholes is discussed on the basis of FMO theory. It is concluded that in most cases, the dominant frontier orbital interaction is between the HOMO(diazo) and the LUMO(heterophosphole), and that the reactivity should decrease in the order­2 >4 >3. The 1,2‐thiaphosphole 9 and 1,3‐azaphosphole 10 have HOMOs of high energy and, therefore, the HOMO(heterophosphole)–LUMO(diazo) interaction is also important. Among the different types of heterophos‐pholes considered here, the 2‐acyl‐1,2,3‐diazaphosphole 5, 3H‐1,2,3,4‐triazaphosphole 8, 1,2‐thiaphosphole 9 and 1,3,4‐thiazaphosphole 14 are predicted to have the highest dipolarophilic reactivities. These conclusions are in qualitative agreement with available experimental results. Copyright © 2003 John Wiley & Sons, Ltd.

ChemInform Abstract: Phosphorus Compounds with Unusual Coordination. Part 31. Cycloaddition of Diazo Compounds onto a P‐Chloro‐phosphaalkene.

AbstractThe title reaction with the methylene phosphine (I) leads even at low temp. to diazaphospholes as shown in the scheme.

ChemInform Abstract: Phosphorus Compounds with Unusual Coordination. Part 19. 1,2,4‐Diazaphospholes by (3 + 2) Cycloaddition of Diazo Compounds onto a Stable Phosphaalkyne.

AbstractThe diazomethyl compounds (II) add regiospecifically onto the phosphaalkyne (I) to give the adducts (III) which isomerize by spontaneous H‐shift to the 1,2,4‐diazaphospholes (IV).