- Synthesis of methyl 2-methylazulene-3-carboxylate in the presence of molecular sieves and reaction with N-bromosuccinimide
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The preparation of methyl 2-methylazulene-1-carboxylate (1) was carried out in the presence of molecular sieves to obtain a good yield. The product was subjected to bromination under different reaction conditions to obtain methyl 1-bromo-2-methylazulene-1-carboxylate (2) and methyl 1-bromo-2-(bromomethyl) azulene-1-carboxylate (3). Copyright Taylor & Francis Group, LLC.
- Wang, Dao-Lin,Xu, Jiao,Gu, Zheng,Han, Shan,Imafuku, Kimiaki
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- A practical approach for the preparation of monofunctional azulenyl squaraine dye
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The synthesis of monofunctional azulenyl squaraine dye NIRQ700 is described. The essential azulene intermediate 3, 1-(methoxycarbonyl)-2-methylazulene, was achieved via [8+2] cycloaddition between lactone 2, 2H-3-methoxycarbonyl-cyclohepta[b]furan-2-one, and the in situ generated vinyl ethers under high temperature and pressure conditions. Methylation on the cycloheptatriene ring of 2-methyl azulene 6 via Meisenheimer-type intermediate following Schrott's method formed the carboxylic acid intermediate 9, 3-(2-methyl-azulen-4-yl)-propionic acid. Condensation of 9 with squaric acid provided the title compound NIRQ700 at moderate yields. The non-fluorescent squaraine dye NIRQ700 absorbed in a 600-700 nm range and potentially can be used to quench a number of available NIR fluorochromes in order to extend the spectrum of biological quenching assays.
- Pham, Wellington,Weissleder, Ralph,Tung, Ching-Hsuan
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p. 3975 - 3978
(2007/10/03)
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- Intermolecular [8+2] cycloaddition reactions of 2H-3-methoxycarbonylcyclohepta[b]furan-2-one with vinyl ethers: An approach to bicyclo[5.3.0]azulene derivatives
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Substituted bicyclo[5.3.0]azulene compounds are synthesized by intermolecular [8+2] cycloaddition reactions of lactone 1 with vinyl ethers - acetal decomposition products - are described. The reactions were found to be temperature and solvent dependent.
- Pham, Wellington,Weissleder, Ralph,Tung, Ching-Hsuan
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- Synthesis and Properties of Fluoroazulenes. II. Electrophilic Fluorination of Azulenes with N-Fluoro Reagents
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1-Fluoro- and 1,3-difluoroazulenes were synthesized for the first time by the electrophilic fluorination of azulenes with N-fluoro reagents. Selective preparation of 1-fluoroazulenes were performed by the fluorination of methyl azulene-1-carboxylates, followed by demethoxycarbonylation in 100% H3PO4 2-Substituted azulenes were fluorinated in higher yields. In the 1HNMR of 1-fluoroazulene, long-range .JFH values were not observed at H-2 and H-8, in contrast to those for 1-fluoronaphthalene. The 1-fluorine atom causes significant bathochromic shifts in the visible absorption of azulene, due to the so-called +Iπ effect.
- Ueno, Tetsuya,Toda, Haruhiko,Yasunami, Masafumi,Yoshifuji, Masaaki
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p. 1645 - 1656
(2007/10/03)
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- A CONVENIENT, ONE-POT AZULENE SYNTHESIS FROM CYCLOHEPTAFURAN-2-ONES AND VINYL ETHER AND ITS ANALOGUES. (II). ACETALS AS REAGENT
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Variously functionalized azulene derivatives were synthesized in one-pot and by the reaction of cycloheptafuran-2-ones with acetals of several aldehydes and ketones on heating at 160-190 deg C in neat or aprotic solvent.
- Nozoe, Tetsuo,Wakabayashi, Hidetsugu,Ishikawa, Sumio,Wu, Chi-Phi,Yang, Paw-Wang
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