Synthesis of New Pyrazolenines and Cyclopropenyl Alcohols Directly from Propargyl Alcohols

2005 ◽  
Vol 2005 (5) ◽  
pp. 289-292 ◽  
Author(s):  
Naceur Hamdi ◽  
Pierre Henry Dixneuf ◽  
Youssef Arfaoui ◽  
Ezzeddine Haloui
Keyword(s):  
Double Bond ◽  
Good Yield ◽  
Dipolar Cycloaddition ◽  
Propargylic Alcohols ◽  
Propargyl Alcohols

The 1,3-dipolar cycloaddition of 2-diazopropane 1 to propargylic alcohols is regioselective and leads to 3H-pyrazoles 3 in good yield. The surprising formation of the tetrasubstitued pyrazolenine 4c from HC=CCH2OH and 1 can be explained via the 1,3-dipolar cycloadduct intermediate followed by a second cycloaddition of 1 to the C=C double bond and loss of dinitrogen. The photolysis of the antibacterial pyrazolenines 3 and 4 selectively gives α and β dimethylcyclopropenyl alcohols 5 and 6.

π-Facial Selectivity in 1,3-Dipolar Cycloaddition Reactions of α-Methylidene-γ-lactone Substituted by 4-Methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl Group in γ-Position

2002 ◽  
Vol 67 (3) ◽  
pp. 353-364 ◽  
Author(s):  
Petr Melša ◽  
Ctibor Mazal
Keyword(s):  
Double Bond ◽  
Carboxylic Acid ◽  
Nitrile Oxide ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Enantiomerically Pure ◽  
Nitrile Imine ◽  
Facial Selectivity ◽  
Excellent Selectivity

Diastereoselectivity of 1,3-dipolar cycloaddition reactions of benzyl azide, diazomethane, a nitrile oxide and a nitrile imine to α-methylidene-γ-lactone dipolarophile was effectively controlled by a bulky γ-substituent, 4-methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl in γ-position of the dipolarophile. The dipoles added from the less hindered face of the double bond with an excellent selectivity. Enantiomerically pure dipolarophile was prepared from the easily available (S)-5-oxotetrahydrohydrofuran-2-carboxylic acid.

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.

The reaction between 2,3-Diphenyl-2H-azirine and Phenyldiazomethane

1973 ◽  
Vol 26 (11) ◽  
pp. 2547 ◽  
Author(s):  
JH Bowie ◽  
B Nussey ◽  
AD Ward
Keyword(s):  
Double Bond ◽  
Good Yield ◽  
Alternative Synthesis

The reaction between 2,3-diphenyl-2H-azirine and phenyldiazomethane produces the stable 1-azido-1,2,3-triphenylprop-1-ene in good yield. The structure is confirmed by an alternative synthesis which indicates that the double bond has the E-configuration.

scholarly journals Synthesis of new A-conjugated Quinolone and Spiroindole Dammaranes by the Ozonolysis of 2,3-Indolodipterocarpol

2018 ◽  
Vol 13 (5) ◽  
pp. 1934578X1801300
Author(s):  
Irina E. Smirnova ◽  
Elmira F. Khusnutdinova ◽  
Alexander N. Lobov ◽  
Oxana B. Kazakova
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Dipolar Cycloaddition ◽  
Intramolecular Rearrangements ◽  
Efficient Access ◽  
One Step ◽  
New Compounds

An one-step and efficient access to the new dammarane A-quinolones by ozonolysis of 2,3-indolodipterocarpol at 0°C through the 1,3-dipolar cycloaddition of ozone to the C2-C3 double bond of the triterpenoid core is reported. In the case of oxidation in AcOH, two spiroindoles were identified as a result of 1,2-cycloaddition of ozone to the C2-C3 double bond with following intramolecular rearrangements of 2,3-epoxy-intermediate. The structures of four new compounds were established by 1H, 13C NMR, COSY, NOSY, HMBC and HSQC analyses.

Model Compounds Related to Saquayamycin. Attempts to Oxygenate the A/B Ring Junction

2002 ◽  
Vol 55 (5) ◽  
pp. 343 ◽  
Author(s):  
M. A. Apponyi ◽  
J. H. Bowie ◽  
B. W. Skelton ◽  
A. H. White
Keyword(s):  
Double Bond ◽  
Maleic Anhydride ◽  
Good Yield ◽  
Ring Opening ◽  
Diels Alder ◽  
Aromatic System ◽  
Model Compounds ◽  
Similar Treatment ◽  
Ring Junction

The aim of this project was to attempt to find a method for introducing the cis-dihydroxyl substitution at the A/B-ring junction of model compounds related to the saquayamycins. The Diels-Alder reactions of maleic anhydride and bromomaleic anhydride with 5,5-dimethyl-3-vinylcyclohexa-1,2-dienyl acetate gave the two required endo-adducts in good yield, namely (octahydrobenzo[e]isobenzofuran-9-yl acetate (6) and (octahydrobenzo[e]isobenzofuran-9-yl acetate (9). Each of these was converted into the B-ring mono-epoxide, namely (H-benzo[e]oxireno-2,3-furan-1-yl acetate (7) and a mixture of two racemic diastereoisomers of 9a-bromo-3,3-dimethyl-7,9-dioxoperhydrobenzo[e]oxi- reno[2,3-f]isobenzofuran-1-yl acetate (12), respectively. It was then hoped to deprotonate both (7) and (12) at the 9a position in order to effect migration of the 8,9 double bond to the 9,9a position. Reaction of (7) with a mild base (pyridine) did not effect any reaction. Similar treatment of (12) did remove the 9a proton, but it also effected ring opening of the epoxide, followed by dehydration and dehydrobromination to give an excellent (but unwanted) yield of the aromatized system (±)-7,7-dimethyl-1,3-dioxo-1,3,5,7-tetrahydrobenzo (e]isobenzofuran-9-yl acetate. Dehydrobromination of (9), and deprotonation of the 9a position, similarly formed the aromatic system (e]isobenzofuran-9-yl acetate (11) in good yield.

Studies on the reaction of nitric oxide with α,β-unsaturated hydrazones

2012 ◽  
Vol 90 (6) ◽  
pp. 510-516 ◽  
Author(s):  
Desuo Yang ◽  
Xiaolin Luo ◽  
Haiyun Zhu ◽  
Yaning Guo ◽  
Longmin Wu
Keyword(s):  
Nitric Oxide ◽  
Double Bond ◽  
Good Yield ◽  
Electrophilic Addition ◽  
Carbon Double Bond ◽  
High Stereoselectivity

α,β-Unsaturated arylhydrazones (1) reacted with nitric oxide (NO) in the presence of a trace of oxygen to give α- (2a–2c, 2e, and 2f) or β-nitro (2d and 2g) unsaturated hydrazones in good yield and with high stereoselectivity. The reaction occurs most likely by an electrophilic addition of NO2 to the carbon–carbon double bond of 1 at its α- or β-position.

A Convenient Synthesis of Tetrasubstituted Pyrazoles from Nitrile Imines and 2-(Thioxothiazolidin-5-ylidene)acetates

Synlett ◽  
2018 ◽  
Vol 29 (07) ◽  
pp. 918-921 ◽  
Author(s):  
Issa Yavari ◽  
Zohreh Taheri ◽  
Maryam Naeimabadi ◽  
Samira Bahemmat ◽  
Mohammad Halvagar
Keyword(s):  
Double Bond ◽  
Dipolar Cycloaddition ◽  
Pyrazole Derivatives ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrazonoyl Chlorides ◽  
Convenient Synthesis ◽  
Nitrile Imines ◽  
Fast Access

Alkyl 2-(3-alkyl-4-oxo-2-thioxothiazolidin-5-ylidene)acetates react with hydrazonoyl chlorides in the presence of triethylamine to ­afford tetrasubstituted pyrazole derivatives. Formally, this transformation is regarded as a 1,3-dipolar cycloaddition of the exocyclic carbon–carbon double bond of the thioxothiazolidine derivatives with nitrile imines generated in situ. This efficient method provides fast access to a range of structurally diverse pyrazoles. The structure of a typical product is confirmed by X-ray crystallography.

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