Azulene, 4,6,8-trimethyl

Azulene, 4,6,8-trimethyl-, 44, 94 Azulenes from cyclopentadienes and 2,4,6-trimethylpyrylium perchlorate, 44, 98... 

Azulene, 4,b,8-trimethyl-from pyrylium salts, 3, 660 Azulenes... 

Azulene106) and 4,6,8-trimethyl azulene109 readily undergo electrophilic attack by cation 75 at the five-membered ring leading to l-(l,2-diphenyl-cyclopropenium)-azulenes 143, which are isoelectronic with indolizinium ions 139/140 and represent cyclic vinylogs of the cyclopropenyl heptafulvenylium system 144. 

Although a small sample of 2,4,6-trimethylpyrylium perchlorate may with care be recrystallized from acetic acid to give white crystals, m.p. 245-247° dec., it is recommended that this not be done with larger quantities. The 2,4,6-trimethylpyrylium perchlorate is of satisfactory purity for use in the 4,6,8-trimethyl-azulene preparation without further purification. 

Nach dem gleichen Schema gelang W. Herz (60) die Gewinnung von trialkylierten bicyclischen Azulenen, von 2,4,5-Trimethyl-[56] und von 2-Isopropyl-4,5-dimethyl-azulen [60]. 

Weitere trialkylierte bicyclische Azulene baute W. Herz (57) — be-sonders im Hinblick auf das in seinem chemischen Bau noch nicht end-giiltig aufgeklarte Pyrethrazulen — nach der BucHNER-Methode liber entsprechende Zwischenstufen auf. Ausgehend von Chlormethyl-p-xylol erhielt er iiber das 2,4,7-Trimethyl-hydrinden 2,4,8-Trimethyl-azulen [58], das nach Farbnuance und Schmelzpunkt des Trinitrobenzo-lates verschieden vom Pyrethrazulen war ... 

Das analog dargestellte l,4,8-Trimethyl-[41] und 1,4-Dimethyl-8-isopropyl-azulen (58), [42] sind violettstichig blau. Beim Versuch der Synthese des 1 -Isopropyl-4,8-dimethyl-azulens iiber das 1-Isopropyl-4,7-Dimethylhydrinden trat Wanderung der Isopropylgruppe von 1 nach 2 zum 2-Isoprapyl-4,8-dimethyl-azulen (59), [61] (Vetivazulen) ein. 

The reaction of 3,3-dichloro-l,2-diphenylcyclopropene (24) with activated benzenoid or non-benzenoid aromatics, such as phenols, naphthols, anthracenols, or 4,6,8-trimethyl-azulene, in refluxing benzene afforded mixed triarylcyclopropenylium salts. 

Sind in den beiden Phenyl-Gruppen des 1,8-Bis-[phenylathinyl]-naphthalin jeweils die 2,6-Stellungen durch Methyl-Gruppen besetzt (z. B. 2,4,6-Trimethyl-phenyl-Restc), so wird keinBenzo-[k]-fluoranthen gebildet, weil dazu mindestens eine freie o-Positionnotig ist. In diesem Fall entsteht nur noch das entsprechendc Azulen-Derivat-5. 

Anthracene, 1-methyl-Anthracene, 2-methyl-Anthracene, 9-methyl-Anthracene, trimethyl-Azulene... 

A number of patents describe the condensation of azulenes with squaric acid (257) or its equivalents and with other dicarbonyl compounds (or equivalents). TTius, azulenothiophene 45a (Scheme 63) yields symmetrical squarate betain 258 (86EAA187015) or (with 259) intermediate 260 and (after hydrolysis and reaction with 1,3,3-trimethyl-2-methyleneindole) unsymmetrical squarate 261 (89DEA3914151). Other examples are those of the two-step reactions of azulenothiophene 16 (Scheme 64) with glutaconedialdehyde or its cyclic equivalent 264 and another azulene to yield azulenium salts 263 and 266, respectively, presumably through intermediates 262 and 265 (90USA4965178). 

A further modification [20] uses a pyrylium salt instead of a pyridinium salt as starting material. For example 4,6,8-trimethyl-azulene was prepared in 65% yield from cyclopentadiene and 2,4,6--trimethylpyrylium perchlorate ... 

Azulene derivatives which have been examined include 5,8,10-trimethyl-benzo[c]aceheptylene (77), the dihydroazulene (78), and the sulphur... 

Trimethyl phosphite ozone Azulene from naphthalene ring via oxidative ring opening... 

Azulenium salts. Ethereal fluoroboric acid added dropwise with stirring and ice-cooling under anhydrous conditions to a soln. of 4,6,8-trimethylazulene in abs. ether, benzaldehyde added to the resulting 4,6,8-trimethylazulenium fluoro-borate, and the product isolated after ca. 4 hrs. l-benzylidene-4,6,8-trimethyl-azulenium fluoroborate. Y 94%.— Azulenes can be converted into azulenium salts, which are derivatives of the tropenium cation, as well as into azuleniate salts, which are derivatives of ihe cyclopentadienyl anion. F. e. and reactions s. K. Hafner, H. Pelster, and J. Schneider, A. 650, 62 (1961) syntheses via azuleniate salts s. A. 650, 80. 

In the Hafner azulene synthesis, pyrylium salts are subjected to cyclocondensation with cyclopentadienyl anions thus 4,6,8-trimethylazulene (50) is obtained from 2,4,6-trimethyl pyrylium salts and Na-cyclopentadienide via intermediates 48/49 (cf also p. 379). 

C15H16N2OS, 3-Ethylidenecyclohexanol 3,5-dinitrobenzoate, 45B, 140 Cl5H17O3P, 7-Methoxyphosphoryl-7-phenylnorcaradiene, 40B, 410 CisH2o02f 2-Isopropyl-a-methyl-5-indanacetic acid, 45B, 140 C15H22O3, 6-Carboxy-7-hydroxymethyl-2,2,4-trimethyl-1,2,3,3a,4,8a-hexahydro-azulene, 44B, 149... 

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