Synthese von Azulen-aldehyden und -ketonen

Häfner, Klaus; Bernhard, Claus

doi:10.1002/ange.19570691605

Cited by 83 publications

(10 citation statements)

References 2 publications

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“…Starting reagents. The protocols described in the literature were used for the synthesis of azulen-1-carbaldehyde, 6 4,6,8-trimethylazulen-1-carbaldehyde, 5 2,4,6-trimethylpyrylium perchlorate, 7 4-(azulen-1-yl)-2,6-dimethylpyrylium perchlorate 2 and 4-(4,6,8-trimethylazulen-1-yl)-2,6-dimethylpyrylium perchlorate. 2…”

Section: Methodsmentioning

confidence: 99%

Pyrylium salts with 2-(azulen-1-yl) vinyl substituents in 2-, 4- and/or 6-positions

Razus¹,

Cristian²,

Nica³

et al. 2011

Arkivoc

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The synthesis of pyrylium perchlorates substituted with one or more azulen-1-ylvinyl groups was performed using conventional coupling conditions and microwave-assisted protocol. The microwave-assisted synthesis protocol is characterized by shorter reaction times, higher product selectivity and enhanced yields. High bathochromic effect was observed in the electronic spectra by substitution of the heterocycle with azulen-1-ylvinyl groups. The 1 H-NMR spectra confirmed the push-pull property of the products.

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Section: Methodsmentioning

confidence: 99%

Pyrylium salts with 2-(azulen-1-yl) vinyl substituents in 2-, 4- and/or 6-positions

Razus¹,

Cristian²,

Nica³

et al. 2011

Arkivoc

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“…[3]). 5-Isopropyl-3,8-dimethyluzulene-I-carbaldehyde ( = guaiazulene-3-carbaldehyde, 2; 1.18 g, 5.2 mmol) I271 [28] and 4a (4.04 g, 10.4 mmol) were reacted in the presence of EtONa (1.06 g, 15.6 mmol)/EtOH (20 ml) in toluene (30 ml) as described for 5a (see I ) . Usual workup yielded 1.41 g (90%) of a 55 :45 mixture of (E)and (2) I,,, 369 (4.23), 284 (4.30), 242 (4.22).…”

Section: I-[( E)-2-(4-chlorophenyl)ethenyl]-468-trimethylazulene ((mentioning

confidence: 99%

New Results in the Synthesis of Styrylazulene Derivatives: Application of the ‘Anil synthesis’ to the preparation of azulenes substituted with styryl groups at the seven‐membered ring

Briquet

Hansen

1994

Helvetica Chimica Acta

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The synthesis of 4,6,8-trimethyl-l-[(E)-4-R-styryl]azulenes 5 (R=H, MeO, Cl) has been performed by Wittig reaction of 4,6,8-trimethylazulene-1-carbaldehyde (1) and the corresponding 4-(R-benzyl)(triphenyl)phosphonium chlorides 4 in the presence of EtONa/EtOH in boiling toluene (see Table 1 ). In the same way, guaiazulene-3carbaldehyde (2) as well as dihydrolactaroviolin (3) yielded with 4a the corresponding styrylazulenes 6 and 7, respectively (see Table 1). It has been found that 1 and 4b yield, in competition to the Witfig reaction, alkylation products, namely 8 and9, respectively (cf. Scheme I ). Thereaction of4,6,8-trimethylazulene(l0) with 4b in tolueneshowed that azulenes can, indeed, be easily alkylated with the phosphonium salt 4b. 4,6,8-Trimethylazulene-2carbaldehyde (12) has been synthesized from the corresponding carboxylate 15 by a reduction (LiAlH,) and dehydrogenation (MnOz) sequence (see Scheme 2). The Swern oxidation of the intermediate 2-(hydroxy-methy1)azulene 16 yielded only 1,3-dichloroazulene derivatives (cf: Scheme 2). The Witrig reaction of 12 with 4a and 4b in the presence of EtONa/EtOH in toluene yielded the expected 2-styryl derivatives 19a and 19b, respectively (see Scheme 3 ) . Again, the yield of 19b was reduced by a competing alkylation reaction of 19b with 4b which led to the formation of the I-benzylated product 20 (see Scheme 3 ) . The 'anil synthesis' of guaiazulene (21) and the 4-R-benzanils 22 (R=H, MeO, C1, Me,N) proceeded smoothyl under standard conditions (powered KOH in DMF) to yield the corresponding 4-[(E)-styryl]azulcne derivatives 23 (see Table 4 ) . In minor amounts, bis(azulen-4-yl) compounds of type 24 and 25 were also formed (see Table 4 ) . The 'anil reaction' of 21 and 4-NOZC,H,CH=NC,H, (22e) in DMF yielded no corresponding styrylazulene derivative 23e. Instead, (E)-1,2-bis(7isopropyl-1-methylazulen-4-yl)ethene (27) was formed (see Scheme 4 ) . The reaction of 4,6,8-trimethylazulene (10) and benzanil (22a) in the presence of KOH in DMF yielded the benzanil adducts 28 to 31 (cf: Scheme 5 ) . Their direct base-catalyzed transformation into the corresponding styryl-substituted aznlenes could not be realized (qf. Scheme 6). However, the transformation succeeded smoothly with KOH in boiling EtOH after N-methylation (cfi Scheme 6).

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“…28 This has a salt-like structure and can be isolated as a perchlorate. 35 , and a series of other compounds. It is emphasised, however, that the role of the condensing agents lies mainly in increasing the electrophilic properties of the carbonyl carbon atom in amides.…”

Section: Nh'mentioning

confidence: 99%

“…In the presence of catalysts (POCI3, PC1 5 , COCI2, SOCLj) they react with dimethylformamide yielding 1-aldehydes and 1,3-dialdehydes 34 » 35 » 52 » 53 . At an intermediate stage of this reaction salts of type (VII) are formed; these are hydrolysed in the presence of alkalis giving azulene aldehydes in 90-95% yield 35 :…”

Section: Cho Chomentioning

confidence: 99%

Formylation and Acylation of Organic Compounds With Substituted Amides of Carboxylic Acids

Dorofeenko¹

1960

Russ. Chem. Rev.

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Synthese von Azulen-aldehyden und -ketonen

Cited by 83 publications

References 2 publications

Pyrylium salts with 2-(azulen-1-yl) vinyl substituents in 2-, 4- and/or 6-positions

Pyrylium salts with 2-(azulen-1-yl) vinyl substituents in 2-, 4- and/or 6-positions

New Results in the Synthesis of Styrylazulene Derivatives: Application of the ‘Anil synthesis’ to the preparation of azulenes substituted with styryl groups at the seven‐membered ring

Formylation and Acylation of Organic Compounds With Substituted Amides of Carboxylic Acids

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