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Photocyclization of Styrylbenzo[a]quinolizinium Salts, 2. Efficient Synthesis of 6a-Azonia[5]helicene Salts Utilizing Steric Interactions of Substituents

✍ Scribed by Sato, Kiyoshi ;Nakajima, Kazuaki ;Arai, Sadao ;Yamagishi, Takamichi

Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
901 KB
Volume
1996
Category
Article
ISSN
0947-3440

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✦ Synopsis

Abstract

The synthesis of a series of substituted 6a‐azonia[5]helicene salts 3d–j and 12a‐azoniabenzo[ghi]perylene salts 4d and 4g by photocyclization of the corresponding 2‐styrylbenzo[a]‐quinolizinium derivatives 2d–j is described. The product ratios of 3d–j and 4d–j depend on the steric hindrance between the two substituents in the 2‐ and 13‐positions of 3d–j. Debromination of bromo‐substituted azonia[5]helicene salts 3h–j with a phosphanenickel(0) complex in methanol leads to parent and monomethyl‐substituted azonia[5]helicene salts 3a, 3b, and 3k, which could not be prepared by photocyclization.

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