Benzonaphthyridine N-Oxides as 1,3-Dipoles

1996 ◽  
Vol 49 (4) ◽  
pp. 523 ◽  
Author(s):  
T Zujewska ◽  
B Bachowska
Keyword(s):  
Ring Opening ◽  
Room Temperature ◽  
Dipolar Cycloaddition ◽  
Dimethyl Acetylenedicarboxylate ◽  
Ring Contraction

Benzonaphthyridine N-oxides give N-ylides with dimethyl acetylenedicarboxylate at room temperature, most probably by 1,3-dipolar cycloaddition followed by ring contraction to form an aziridine derivative, and ring opening.

Formation and HERON Reactivity of Cyclic N,N-Dialkoxyamides

2014 ◽  
Vol 67 (3) ◽  
pp. 507 ◽  
Author(s):  
Stephen A. Glover ◽  
Adam A. Rosser ◽  
Avat (Arman) Taherpour ◽  
Ben W. Greatrex
Keyword(s):  
Nmr Spectroscopy ◽  
Ring Opening ◽  
Room Temperature ◽  
Butyl Ester ◽  
Hypervalent Iodine ◽  
Ring Contraction ◽  
Esi Ms ◽  
First Time

Cyclic N,N-dialkoxyamides have been made, for the first time, by hypervalent iodine oxidation of β- and γ-hydroxyhydroxamic esters 17, 19, and 21. The fused γ-lactam products, N-butoxy- and N-benzyloxybenzisoxazolones (22a and 22b), are stable while alicyclic γ-lactam and δ-lactam products, 24 and 25, although observable by NMR spectroscopy and ESI-MS are unstable at room temperature, undergoing HERON reactions. The γ-lactam 24 undergoes exclusive ring opening to give a butyl ester-functionalised alkoxynitrene 28. The δ-lactam 25, instead, undergoes a HERON ring contraction to give butyrolactone (27). The structures of model γ- and δ-lactams 6, 7, and 8 have been determined at the B3LYP/6-31G(d) level of theory and the γ-lactams are much more twisted than the acyclic N,N-dimethoxyacetamide (5) resulting in a computed amidicity for 6 of only 25 % that of N,N-dimethylacetamide (3). The HERON reactions of N,N-dimethoxyacetamide (5) and alicyclic models 6 and 8 have been modelled computationally. The facile ring opening of 6 (EA = 113 kJ mol–1) and ring contraction of 8 (EA = 145 kJ mol–1) are predicted well, when compared with the HERON rearrangement of 5 (EA = 178 kJ mol–1).

A study on the reaction of 3-alkyl(aryl)imidazo[1,5-a]pyridines with ninhydrin

2018 ◽  
Vol 73 (6) ◽  
pp. 413-421
Author(s):  
Mervat S. Sammor ◽  
Mustafa M. El-Abadelah ◽  
Ahmad Q. Hussein ◽  
Firas F. Awwadi ◽  
Salim S. Sabri ◽  
...  
Keyword(s):  
Substitution Reaction ◽  
Electrophilic Substitution ◽  
Room Temperature ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
Dimethyl Acetylenedicarboxylate ◽  
Electrophilic Substitution Reaction ◽  
Carbonyl Carbon ◽  
Alkyl Aryl

AbstractThe reaction of 3-alkyl(aryl)imidazo[1,5-a]pyridines (1) with ninhydrin in dichloromethane at room temperature delivered good yields of the respective 2-hydroxy-2-(imidazo[1,5-a]pyridine-1-yl)indene-1,3-diones. In the presence of dimethyl acetylenedicarboxylate (DMAD), this uncatalyzed electrophilic substitution reaction, involving C-1 (in 1) and the central C=O (in ninhydrin), takes precedence over the three-component 1,4-dipolar cycloaddition reaction. This selectivity is probably due to the higher electrophilicity of the carbonyl carbon-2 in ninhydrin as compared to that of the sp-carbon atoms in DMAD, augmented with the high nucleophilicity of carbon-1 in 1.

Reactions of 4-Pyrones with Azomethine Ylides as a Chemo­selective Method for the Construction of Multisubstituted Pyrano[2,3-c]pyrrolidines

Synthesis ◽  
2021 ◽  
Author(s):  
Dmitrii L. Obydennov ◽  
Vyacheslav D. Steben’kov ◽  
Konstantin L. Obydennov ◽  
Sergey A. Usachev ◽  
Vladimir S. Moshkin ◽  
...  
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Azomethine Ylides ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Computational Studies ◽  
Carbon Double Bond ◽  
Reactivity Indexes ◽  
Reaction Proceeds

Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.

Unprecedented access to functionalized pyrrolo[2,1-a]isoquinolines from the domino reaction of isoquinolinium ylides and electrophilic benzannulated heterocycles

2021 ◽  
Author(s):  
Sheba Ann Babu ◽  
Rajalekshmi A. R. ◽  
Nitha P. R. ◽  
Vishnu K. Omanakuttan ◽  
Rahul P. ◽  
...  
Keyword(s):  
Ring Opening ◽  
Domino Reaction ◽  
Dipolar Cycloaddition

The reaction between electrophilic benzannulated heterocycles and isoquinolinium methylides results in a domino dipolar cycloaddition-ring opening transformation, generating functionalized pyrrolo[2,1-a]isoquinolines and S–S-bridged bis-pyrrolo[2,1-a]isoquinolines.

N-Chlorinative Ring Contraction of 1,4-Dimethoxyphthalazines via a Bicyclization/Ring-Opening Mechanism

Synthesis ◽  
2020 ◽  
Author(s):  
Jeong Kyun Im ◽  
Ilju Jeong ◽  
Jun-Ho Choi ◽  
Won-jin Chung ◽  
ByeongDo Yang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Reaction Conditions ◽  
Ring Contraction ◽  
Silyl Group ◽  
Favorskii Rearrangement ◽  
Mechanistic Analysis ◽  
Group A ◽  
Overall Efficiency ◽  
Trichloroisocyanuric Acid

AbstractAn unprecedented N-chlorinative ring contraction of 1,2-diazines was discovered and investigated with an electrophilic chlorinating reagent, trichloroisocyanuric acid (TCICA). Through optimization and mechanistic analysis, the assisting role of n-Bu4NCl as an exogenous nucleophile was identified, and the optimized reaction conditions were applied to a range of 1,4-dimethoxyphthalazine derivatives. Also, an improvement of overall efficiency was demonstrated by the use of a labile O-silyl group. A bicyclization/ring-opening mechanism, inspired by the Favorskii rearrangement, was proposed and supported by the DFT calculations. Furthermore, the efforts on scope expansion as well as the evaluation of other electrophilic promoters revealed that the newly developed ring contraction reactivity is a unique characteristic of 1,4-dimethoxyphthalazine scaffold and TCICA.

scholarly journals Synthesis and Characterization of Polyphosphazenes Modified with Hydroxyethyl Methacrylate and Lactic Acid

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Evelyn Carolina Martínez Ceballos ◽  
Ricardo Vera Graziano ◽  
Gonzalo Martínez Barrera ◽  
Oscar Olea Mejía
Keyword(s):  
Lactic Acid ◽  
Ring Opening ◽  
Room Temperature ◽  
Block Structure ◽  
Ring Opening Polymerization ◽  
Synthesis And Characterization ◽  
Poly Lactic Acid ◽  
Hydroxyethyl Methacrylate ◽  
H Nmr

Poly(dichlorophosphazene) was prepared by melt ring-opening polymerization of the hexachlorocyclotriphosphazene. Poly[bis(2-hydroxyethyl-methacrylate)-phosphazene] and poly[(2-hydroxyethyl-methacrylate)-graft-poly(lactic-acid)-phosphazene] were obtained by nucleophilic condensation reactions at different concentrations of the substituents. The properties of the synthesized copolymers were assessed by FTIR,1H-NMR and31P-NMR, thermal analysis (DSC-TGA), and electron microscopy (SEM). The copolymers have a block structure and show twoTg's below room temperature. They are stable up to a temperature of 100°C. The type of the substituents attached to the PZ backbone determines the morphology of the polymers.

Nucleophilic Phosphine-Promoted Domino Reaction of Dialkyl Acetylenedicarboxylates and 3-Arylamino-1-methyl-1H-pyrrole-2,5-diones

Synthesis ◽  
2018 ◽  
Vol 50 (18) ◽  
pp. 3715-3722 ◽  
Author(s):  
Ying Han ◽  
Chao-Guo Yan ◽  
Chang-Zhou Liu ◽  
Yuan-Yuan Zhang ◽  
Jing Sun
Keyword(s):  
Room Temperature ◽  
Domino Reaction ◽  
Dimethyl Acetylenedicarboxylate ◽  
Dialkyl Acetylenedicarboxylates ◽  
Three Component Reaction

The three-component reaction of triphenylphosphine, dimethyl acetylenedicarboxylate and 3-arylamino-1-methyl-1H-pyrrole-2,5-diones in CH2Cl2 at room temperature resulted in functionalized 3-(triphenyl-λ5-phosphanylidene)succinates in nearly quantitative yields. However, tri(n-butyl)phosphine promoted reaction of dialkyl acetylenedicarboxylates and 3-arylamino-1-methyl-1H-pyrrole-2,5-diones in CH2Cl2 afforded functionalized pyrrolo[3,4-b]pyridine-4-carboxylates in satisfactory yields.

Sign in / Sign up

Export Citation Format

Share Document