Azulene-1-azo-(3 0 -and 4 0 -pyridines) were synthesised from azulenes and diazotized aminopyridines. The mechanism for the generation of the diazonium salt was discussed. The obtained azulene-1-azo pyridines were alkylated with alkyl, benzyl and allyl halides. 825

Rings with 7 or more membersRings with 7 or more members Q 0050 3-Substituted Azulene-1-azo(4'-methylbenzenes). Preparation and Study ofSpectral Characteristics. -(RAZUS, A. C.; BIRZAN*, L.; NAE, S.; CRISTIAN, L.; CHIRALEU, F.; MAGANU, M.; CIMPEANU, V.; TARKO, L.; Rev. Roum. Chim. 48 (2003) 6, 455-461; Nenitzescu Inst. Org. Chem., Roum. Acad., RO-77208 Bucharest, Rom.; Eng.) -M. Kowall 15-076

Several derivatives belonging to a new compound class, namely azulene-1-azo-2'-thiazoles, were prepared by the diazotization of 2-aminothiazoles in the presence of HNO 3 /H 3 PO 4 followed by the coupling of diazonium salts with azulenes in buffered medium. The reactions proved to be general for this class, the yields are, however, considerably influenced by the substituents at thiazole moiety. For the first time a Noxide provided from an amino substituted five-member nitrogenous heterocycle was diazotized and coupled. The structure of the obtained compounds was assigned and their physico-chemical properties were discussed. The new azulene azo derivatives exhibit a strong bathochromic shift in UV-Vis due to the intense push-pull effect of aromatic system and to the intrinsic properties of thiazole moiety.J. Heterocyclic Chem., 40, 995 (2003). Introduction.As a part of our continuing interest in the study of synthesis and properties of azulene-1-azoaromatics we have recently investigated the azulene-1-azopyridines derivatives, 1 [1]. Besides the interesting structure and properties of such compounds, it was anticipated that they possess high β hyperpolarizability [2] therefore they can be attractive in the development of various technical fields as dyes and pigments and in the display, storage or transmission of information. Another applicability of azulene-1-azopyridines can be found in electrochemistry, for the generation of an electrically conducting polymer film at the electrode surface [3].Az-N=N-Py 1 Az = unsubstituted or substituted azulen-1-yl Py = 2-, 3-or 4 piridyl group, unsubstituted or N-substituted The similarity between the electronic distributions over the pyridine and thiazole systems prompted us to investigate the synthesis and some chemical and optical properties of the new class of azulene-1-azo-2'-thiazole derivatives. Other arguments for our study were the theoretical [4] and experimental works [5,6] which revealed the high β hyperpolarizability for 2-vinyl or 2-azo-thiazoles substituted with NO 2 at C-5.Synthesis of Azulen-1-azo-2'-thiazoles and their 3'-Oxo derivatives.A. Azulen-1-azo-2'-thiazoles.For our study we have chosen the 2-azothiazole derivatives unsubstituted or with different substituents at 5 position provided from stable and accessible corresponding 2-aminothiazoles. Due to increased thiazole stability induced by the phenyl substituted at C-4 these derivatives were also included in this study.Although the first thiazolamines diazotization followed by azo coupling was already reported in the 19 th century [7], some difficulties arose from the low basicity of the thiazolamines or from the possible diazotization reversibility in thermodynamic conditions followed by the nitrosation of coupling substrate [8] (azulene in our case). Therefore, we tried to generate the azulene-1-azo-2'-thiazoles in a similar way as for the corresponding pyridine derivatives [1a].The diazotization was carried out in a mixture of phosphoric and nitric acids using solid sodium nitrite and the coupling ...

Azulene-1-azo-2'-thiazoles. Synthesis and Properties. -Various derivatives of the title compounds are prepared by diazotization of 2-aminothiazole derivatives followed by coupling of the diazonium salts obtained with azulenes in buffered medium. The yield of reaction is considerably influenced by the substituents at the thiazole moiety. The novel azulene azo derivatives show a strong bathochromic shift in UV-Vis due to the intense push-pull effect of aromatic system and to the intrinsic properties of thiazole moiety. -(RAZUS*, A. C.; BIRZAN, L.; NAE, S.; SURUGIU, M. N.; CIMPEANU, V.; J. Heterocycl. Chem. 40 (2003) 6, 995-1004; Inst. Org. Chem., Rom. Acad., Bucharest, Rom.; Eng.) -F. Santoso

Azulenic β-diketones were synthesized in the reaction of different β-diketones with 1-azulenecarboxylic acid chloride, in the presence of MgCl 2 and pyridine, as a result of condensation and subsequent acyl elimination. The obtained dicarbonyl compounds were used for the generation of azulenic pyrazoles and isoxazoles. The structures and some physicochemical properties of the obtained products were reported.