Aromatic and Antiaromatic Cyclophane‐type Hexaphyrin Dimers. Issue 2 (4th January 2019)

• Record Type: Journal Article
• Authors: Nakai, Akito; Yoneda, Tomoki; Ishida, Shin‐ichiro; Kato, Kenichi; Osuka, Atsuhiro
• Is Part Of: Chemistry, an Asian journal. Volume 14:Issue 2(2019)
• Page Start: 256
• Page End: 260
• Publication Date: 2019-01-04
• Subjects: aromaticity -- cyclophane -- expanded porphyrin -- hexaphyrin -- olefin metathesis; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.201801751
• Languages: English
• ISSNs: 1861-4728

Abstract

Abstract: A peripherally strapped [28]hexaphyrin takes a rectangular conformation and exhibits antiaromatic character. A cyclophane‐type dimer consisting of such [28]hexaphyrins was synthesized from hexakis(pentafluorophenyl) [26]hexaphyrin via SN Ar reaction with allyl alcohol, one‐pot intra‐ and intermolecular olefin metathesis under improved Hoveyda–Grubbs catalysis, and final reduction with NaBH4 . The cyclophane‐type structures of [26]‐ and [28]hexaphyrin dimers have been revealed by X‐ray analysis. Studies on the structural, optical, and electronic properties have led to a conclusion that there is no favorable electronic interaction between the two [28]hexaphyrin segments and thus no indication of 3D aromaticity. Abstract : Blinding the Cyclops : Cyclophane‐type [26]‐ and [28]hexaphyrin dimers have been synthesized from hexakis(pentafluorophenyl) [26]hexaphyrin via a six‐fold SN Ar reaction with allyl alcohol and subsequent olefin metathesis, and structurally well characterized by X‐ray analysis. In the latter dimer, there is no favourable interaction between the [28]hexaphyrin segments and hence no appearance of 3D‐aromaticity.