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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 by Anne Andrée Sophie Briquet; Hans‐Jürgen Hansen is a Chemistry article available to read on EtoBox.

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## Abstract The synthesis of 4,6,8‐trimethyl‐1‐[(__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‐3‐carbaldehyde (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 __Wittig__ reaction, alkylation products, namely 8 and 9, respectively (__cf. Scheme 1__). The reaction of 4,6,8‐trimethylazulene (10) with 4b in toluene showed that azulenes can, indeed, be easily alkylated with the phosphonium salt 4b. 4,6,8‐Trimethylazulene‐2‐carbaldehyde (12) has been synthesized from the corresponding carboxylate 15 by a reduction (LiAlH~4~) and dehydrogenation (MnO~2~) sequence (see __Scheme 2__). The __Swern__ oxidation of the intermediate 2‐(hydroxymethyl)azulene 16 yielded only 1,3‐dichloroazulene derivatives (__cf. Scheme 2__). The __Wittig__ reaction of 12 with 4a and 4b in the presence of EtONa/EtOH in toluene y

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Author

Anne Andrée Sophie Briquet; Hans‐Jürgen Hansen

Publisher

John Wiley and Sons; Wiley (John Wiley & Sons); Wiley-Blackwell; Wiley (ISSN 0018-019X)

Published

1994

Language

DE

Field

Chemistry (Physical Sciences)