A Short Syntheses of 1,2‐Dimethylazulenes

Fallahpour, Reza; Hansen, Hans‐Jürǵen

doi:10.1002/hlca.19920750705

Cited by 16 publications

(14 citation statements)

References 11 publications

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“…The monoazido‐substituted ligand 4‐azido‐2,2′‐bipyridyl ( 1 ) was prepared from its nitro‐substituted analogue by reaction with sodium azide in dimethylformamide (DMF) at 100 °C in a procedure modified from that reported previously by Fallahpour 52. After purification by flash chromatography, 1 was isolated as a pale yellow solid in excellent yield.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Azidobipyridyl Ruthenium Complexes and Their “Click” Chemistry Derivatives

2013

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The ligand 4‐azido‐2,2′‐bipyridyl (1) has been used to prepare 1,2,3‐triazole‐substituted ligands through copper‐catalyzed alkyne/azide cycloaddition (CuAAC or “click” chemistry) with phenylacetylene, ethynylferrocene and 2‐ethynylpyridine to yield 4‐(4‐phenyl‐1,2,3‐triazol‐1‐yl)‐2,2′‐bipyridyl (2a), 4‐(4‐ferrocenyl‐1,2,3‐triazol‐1‐yl)‐2,2′‐bipyridyl (2b) and 4‐[4‐(pyridyl‐2‐yl)‐1,2,3‐triazol‐1‐yl]‐2,2′‐bipyridyl (2c). Complexes of the form [Ru(p‐cymene)(Cl)(L)]PF6 (3, L = 1; 4a, L = 2a; 4b, L = 2b) were then prepared and characterized. We also report the synthesis of the complex of the analogous ligand 4,4′‐bisazido‐2,2′‐bipyridyl (1′), [Ru(p‐cymene)(Cl)(1′)]PF6 (3′). Complexes 4a and 4b were also prepared by an alternative route, whereby 3 undergoes CuAAC coupling with phenylacetylene and ethynylferrocene respectively. Complexes prepared with ligands that are pre‐assembled or “clicked” at the metal show identical 1H NMR spectra. CuAAC coupling of 3 and 2‐ethynylpyridine results in the formation of the complex [Ru(p‐cymene)(Cl)(2c)]PF6 (4c), which contains a coordinatively vacant pyridyltriazole moiety. The reaction of [Ru(p‐cymene)(Cl)2]2 with pre‐assembled 2c results in the formation of the dinuclear complex [{Ru(p‐cymene)(Cl)}2(2c)]·2PF6 (5), which incorporates ruthenium atoms at both bipyridyl and pyridyltriazole binding domains. The 1H NMR spectrum of the complex shows two signals for the triazole ring proton as well as duplicate signals for other protons of the bridging ligand, which indicates that 5 is produced as a mixture of diastereoisomers. The complex [{Ru(p‐cymene)Cl}2{di‐4‐([1‐{2,2′‐bipyrid‐4‐yl}triazol‐4‐yl]methyl)ether}][PF6]2 (7) was also prepared through the coupling of 3 with dipropargyl ether.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Azidobipyridyl Ruthenium Complexes and Their “Click” Chemistry Derivatives

2013

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“…However, whereas azulene-2-methanols can easily be reduced to the corresponding 2-methylazulenes with Et 3 SiH/CF 3 COOH (cf. [29]), this procedure failed completely in the case of the mixture 11a/11b. Treatment of 11a/11b with MnO 2 in CH 2 Cl 2 led back to the mixture 10a/10b.…”

Section: Methodsmentioning

confidence: 90%

Tetramethylheptalenes and Their Tricarbonylchromium Complexes: Synthesis, Structures, and Thermal Rearrangements

Uebelhart

Linden

Hansen

et al. 1999

HCA

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“…H -N M R : 8.23 (d, J(7,8) = (5) 3.66 (3.79), 321 (4.35), 304(4.31), 292 (sh, 4.19), 251 (3.95),218 (4.09); l,i, 360 (3.77), 308 (4.30), 272 (3.92), 230 (3. (5)); 3.15 (s,); 2.96 (s, Me-C(4)); 1,4,8-trimethylazulene (6b). See [6]. 1.3.2.…”

Section: Experimental Partmentioning

confidence: 97%

Reaction of Hydroxymethyl‐ and Alkyl‐Substituted Azulenes with Manganese Dioxide

Fallahpour

Sigrist

Hansen

1995

Helvetica Chimica Acta

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Dedicated to Richard Neidlein on the occasion of his 65th birthday (21.VII.95) It is shown that the 2-(hydroxymethyl)-l-methylazulenes 6 are being oxidized by activated MnO, in CH,Cl, at room temperature to the corresponding azulene-l,2-dicarbaldehydes 7 (Scheme 2 ) . Extension of the MnO, oxidation reaction to I-methyl-and/or 3-methyl-substituted azulenes led to the formation of the corresponding azulene-1-carbaldehydes in excellent yields (Scheme 3 ) . The reaction of unsymmetrically substituted 1,3-dimethylazulenes (cf. 15 in Scheme 4 ) with MnO, shows only little chemoselectivity. However, the observed ratio of the formed constitutionally isometric azulene-I-carbaldehydes is in agreement with the size of the orbital coefficients in the HOMO of the azulenes. The reaction of guaiazulene (18) with MnO, in dioxane/H,O at room temperature gave mainly the expected carbaldehyde 19. However, it was accompanied by the azulene-diones 20 and 21 (Scheme 5). The precursor of the demethylated compound 20 is the carbaldehyde 19. Similarly, the MnO, reaction of 7-isopropyl-4-methylazulene (22) as well as of 4,6,8-trimethylazulene (24) led to the formation of a mixture of the corresponding azulene-l,5-diones and azulene-1,7-diones 20j23 and 25/26, respectively, in decent yields (Schemes 6 and 7 ) . No MnO, reaction was observed with 5,7-dimethylazulene.

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A Short Syntheses of 1,2‐Dimethylazulenes

Abstract: Dimethyl azulene-l,2-dicarboxylates are reduced with a 4 5 molar excess of DIBAH in Et20/hexane at 0" to yield the corresponding 2-(hydroxymethyl)-l-methylazulenes which can be further reduced to 1,2-dimethylazulenes on treatment with Et,SiH in TFA at 60" (cf the Table).

Cited by 16 publications

References 11 publications

Synthesis and Characterization of Azidobipyridyl Ruthenium Complexes and Their “Click” Chemistry Derivatives

Synthesis and Characterization of Azidobipyridyl Ruthenium Complexes and Their “Click” Chemistry Derivatives

Tetramethylheptalenes and Their Tricarbonylchromium Complexes: Synthesis, Structures, and Thermal Rearrangements

Reaction of Hydroxymethyl‐ and Alkyl‐Substituted Azulenes with Manganese Dioxide

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