- Synthesis of internally alkylated azuliporphyrins
-
Examples of internally alkylated azuliporphyrins were prepared by MacDonald-type 3 + 1 condensations. 2-Methyl- and 2-ethylazulene reacted with an acetoxymethylpyrrole in the presence of an acid catalyst to give azulitripyrranes. Following cleavage of the terminal protective groups, condensation with a diformylpyrrole in the presence of hydrochloric acid and oxidation with ferric chloride afforded 21-alkylazuliporphyrins. An azulene dialdehyde similarly reacted with an N-methyltripyrrane to generate a 23-methylazuliporphyrin. The products could only be isolated in protonated form and the free-base internally alkylated azuliporphyrins proved to be unstable. Nevertheless, the dications are highly diatropic and the internal alkyl group resonances were shifted upfield to beyond -3 ppm. Reaction of a 23-methylazuliporphyrin with palladium(II) acetate primarily afforded a palladium(II) complex with loss of the internal methyl substituent. However, two palladium(II) benzocarbaporphyrins were also identified that were formed by sequential oxidative ring contraction and methyl group migration. Internally alkylated azuliporphyrins provide new insights into the reactivity of the system and the results show that the introduction of alkyl substituents within porphyrinoid cavities greatly modifies the properties of these structures.
- Moriones, Julian S. D.,Latham, Alissa N.,Lash, Timothy D.
-
p. 817 - 829
(2020/01/21)
-
- A practical approach for the preparation of monofunctional azulenyl squaraine dye
-
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
-
p. 3975 - 3978
(2007/10/03)
-
- Transition metal compounds
-
The present invention relates to a catalyst for polymerization of α-olefin, which comprises: an essential component (A) of a transition metal compound, an essential component (B) of an ion exchangeable layer compound except for silicate, or an inorganic silicate, and an optional component (C) of an organoaluminum compound, said component (A) being represented by the general formula (I):
- -
-
-
- Catalyst component for use in the polymerization of α-olefins and process for producing α-olefin polymers using the same
-
A catalyst component for use in the polymerization of α-olefins, comprising a compound represented by the following general formula I!: STR1 wherein R1 s represent a hydrogen atom, a C1-6 hydrocarbon group or a C1-12 hydrocarbon group containing silicon; each of R2 and R3 which forms the condensed ring represents a divalent C3-20 saturated or unsaturated hydrocarbon group, provided that at least one of R2 and R3 forms a ring condensed with the cyclopentadiene which is a seven- to twelve-membered ring having an unsaturated bond inherent in R2 or R3 ; Q represents a C1-20 divalent hydrocarbon group, a silylene group, a silylene group with a C1-20 hydrocarbon group, a germylene group, or a germylene group with a C1-20 hydrocarbon group; X and Y represent H, a halogen, a C1-20 hydrocarbon group, or a C1-20 hydrocarbon group containing oxygen, nitrogen or phosphorus; and M represents a Group IVB to VIB transition metal of the Periodic Table. Production of α-olefin polymers having a high melting point and a high molecular weight in a high yield and a process for producing α-olefin polymers is made possible upon the use of the catalyst.
- -
-
-
- Synthesis and Properties of Fluoroazulenes. II. Electrophilic Fluorination of Azulenes with N-Fluoro Reagents
-
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
-
p. 1645 - 1656
(2007/10/03)
-
- Stereocontrolled double ring expansion of fused allylidenecyclopropanes. A novel route to hydroazulenes and other fused bicyclic systems
-
A variety of 1-(phenylthio)-1-(trimethylsilyl)cyclopropanes, fused to five-, six-, and seven-membered rings, have been prepared by several procedures and reductively lithiated by means of aromatic radical anions. The resulting 1-lithio-1-(trimethylsilyl)cyclopropanes have been treated in most cases with α,β-unsaturated aldehydes, followed by potassium tert-butoxide to yield allylidenecyclopropanes. The latter, upon thermal rearrangement either in a sealed tube or in a flash vacuum pyrolysis apparatus, undergo a double ring expansion to cyclopentenocyclohexenes, -cycloheptenes (hydroazulenes), or -cyclooctenes. When the distal double bond of the allylidenecyclopropane possesses a terminal trans substituent, that substituent in the hydroazulene pyrolysis product is predominantly in the exo position (cis to the hydrogen atom at the ring junction carbon atom); cis substituents end up mainly in the endo position. Thus, the ring closure occurs mainly in a conrotatory sense. When the distal unsaturation is incorporated into a ring, a tricyclic system results. Carbonyl functionality can be introduced into either position of the five-membered rings and either of the two carbon atoms adjacent to the ring junction of the seven- or eight-membered ring of the ring expansion products by using appropriately substituted rearrangement substrates. Complete regioselectivity is observed when the original six- or seven-membered ring has a ketone group adjacent to the ring junction; the product is a completely conjugated dienone. Complete regioselectivity in the opposite sense is observed upon rearrangement of the corresponding kinetic silyl enol ether. This methodology is demonstrated by the synthesis of (+)-9-epiledene, containing the gross structural features of the aromadendrene sesquiterpenes, and of (±)-α-bulnesol, a guiazulene sesquiterpene.
- Shook, Craig A.,Romberger, Matthew L.,Jung, Sang-Hun,Xiao, Manchao,Sherbine, James P.,Zhang, Birong,Lin, Fu-Tyan,Cohen, Theodore
-
p. 10754 - 10773
(2007/10/02)
-
