Synthesis of azulenic compounds with a homo- or hetero-atomic double bond at position 1

Razus, Alexandru C.; Bîrzan, Liviu

doi:10.24820/ark.5550190.p010.400

Cited by 6 publications

(8 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ability of azulene to stabilize positive charge suggested to Razus et al the use of this moiety to increase the stability of the heteroaromatic cations as such for pyrylium and pyridinium salts. The obtained results were reported in a detailed review [51]; therefore, only a few data on these studies are presented in Scheme 22. The syntheses are based on the condensation of aldehydes with a reactive methyl group in the presence of a dehydrating agent as acetic anhydride [51].…”

Section: The Dance Of Two or More Azulenes With Various Spacers ("Dan...mentioning

confidence: 99%

Dancing with Azulene

Razus

2022

Symmetry

View full text Add to dashboard Cite

It seems interesting to adopt the idea of dance in the context of the arrangement of molecular blocks in the building of molecular systems. Just as various dances can create various feelings, the nature and arrangement of molecular blocks in the generated molecular system can induce different properties. We consider obtaining such “dancing” systems in which the still little-known azulene moieties are involved. The dark blue nonbenzenoid aromatic azulene has one less axis of symmetry relative to the two axes of its isomer, i.e., the fully benzenoid naphthalene, acquiring valuable properties as a result that can be used successfully in technical applications. In a dancing system, the azulene moieties can be connected directly, or a more or less complex spacer can be inserted between them. Several azulene moieties can form a linear oligomer or a polymer and the involvement of azulene moieties in nonlinear molecules, such as crown ethers, calixarenes, azuliporphyrins, or azulenophane, is a relatively new and intensely studied topic. Some aspects are covered in this review, which are mainly related to obtaining the mentioned azulene compounds and less to their characterization or physico-chemical properties.

show abstract

Section: The Dance Of Two or More Azulenes With Various Spacers ("Dan...mentioning

confidence: 99%

Dancing with Azulene

Razus

2022

Symmetry

View full text Add to dashboard Cite

show abstract

“…The building of carbon double bond between an aryl and 1 position of azulenes occurs following Wittig condensation [12]. The commercially availability of several 4'-formylbenzo-crown-ethers prompted us to use them as starting materials for the reaction.…”

Section: Synthesismentioning

confidence: 99%

New Benzo- and Dibenzo-Crown Ethers with (Azulen-1-yl)Vinyl Substituents

Bîrzan¹,

Tecuceanu²,

Cristea³

et al. 2021

Rev. Chim.

View full text Add to dashboard Cite

Several 1-azulenyl vinyl crown ethers were synthesized starting from (1-azulenylmethyl) triphenylphosphonium iodide and 4-formylbenzo-crown ethers in the Wittig reaction conditions. The reaction worked in fair conditions and the obtained mixtures of geometric isomers were separated using column chromatography. The isomers were identified using 1H-NMR spectra and the mass spectra were recorded using ESI. The UV-vis spectra showed bathochromic effect in Z isomer compared with the E one.

show abstract

“…This can be explained by the lower reactivity of C6 anion than that of C4 anion, which requires a longer reaction time, allowing the formation of by-products. Moreover, 6-methylazulene is susceptible to ring-opening processes through nucleophilic attack, due to the absence of the protecting methyl group at C4 (8).…”

Section: Synthesismentioning

confidence: 99%

“…Those situated in positions 4 and 8, close to negatively polarized small cycle, possess a higher acidity than that in 6-position, which is less acidic. Therefore, it is assumed that the kinetic route of reaction favors the condensation in position 4 (8) whereas the reaction with methyl substituted at 6-position will lead to more stable alkenes in the thermodynamic control. Our results are labeled a, whereas the products for thiophen-2-yl condensation in the presence of sodium Nmethylanilide, which are previously reported [14], are shown on label b in Scheme 5.…”

Section: Scheme 3 Reaction Of 48-dimethyl-6-tert-butylazulene With mentioning

confidence: 99%

“…For a long time our research has focused on the synthesis and properties of azulene-containing compounds with (hetero)aryl-azo [1][2][3][4][5], imino [6] and ethene groups [7]. Most of the papers were reviewed as 1-vinylazulenes with aromatic and heteroaromatic moieties attached to the C=C bond [8]. Other reviews treated them as separate chapters [9,10].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Preparation of Azulenes Substituted at Seven-Membered Cycle with 2- and 3-thiophenevinyl Groups

Bîrzan¹,

Tecuceanu²,

Drăghici³

et al. 2020

Rev. Chim.

View full text Add to dashboard Cite

This paper comes as a continuation of our efforts to prepare vinylazulenes, moving our attention to the seven-membered azulene cycle. Several azulenic substrates were tested in order to study the possibility of preparation of poly(thiophenevinyl)azulenes, needed for the generation of dendrimeric structures. The compounds containing methyls in positions 4,6 and 8 could be condensed with 2- and 3- thiophenecarbaldehyde in tBuOK/THF yielding mono-, bis- and tris- condensed products in function of molar ratio of reagents, catalyst, solvent. The reaction works in thermodynamic control, preferring 6-position instead of 4(8)-position, which generates less stable alkenes (steric hindrance) and has a trans stereochemistry. Usually mixtures of products are obtained if more condensation position are present, even if a large aldehyde excess is used. In forcing conditions, the intermediate alcohols suffer an Oppenauer hydride transfer to the excess aldehyde, generating undesired ketones. For condensation of a methyl group situated on the five-membered cycle it must be activated by substitution with +PPh3 followed by a Wittig condensation.

show abstract

Synthesis of azulenic compounds with a homo- or hetero-atomic double bond at position 1

Abstract: This work reviews the synthetic routes for the generation of 1-vinylazulenes, azulen-1-yl diazenes and azulen-1-yl imines. The wide range of substituents at the studied double bonds involves varied synthetic routes and a great number of exemplified compounds.

Cited by 6 publications

References 53 publications

Dancing with Azulene

Dancing with Azulene

New Benzo- and Dibenzo-Crown Ethers with (Azulen-1-yl)Vinyl Substituents

Preparation of Azulenes Substituted at Seven-Membered Cycle with 2- and 3-thiophenevinyl Groups

Contact Info

Product

Resources

About