Helicene macrocycle

Diene macrocycle 53 had, in fact, been previously synthesized in 1977 by Wen-nerstrom and Thulin via a Wittig reaction [23, 24]. It was subsequently irradiated in the presence of iodine to give the bi-4,5-phenanthrene cyclophane 57 (Scheme 6.9). Oxidation of cyclophane 57 by heating to 140 °C in a melt composed of NaCl and AICI3 provided the fused helicene 58 [23]. Attempts to further oxidize 58 to the fully closed derivative, however, were not successful. 

Binaphthyl based structures are not the only chiral groups that have been incorporated into the backbone of chiral macrocydes. Recently, there has been an increasing number of reports of macrocydes that are chiral due to the incorporation of a helicene moiety [62]. One of the earhest stmctures to be reported was from Wennerstrom and coworkers [63] and linked directly two [5]hehcenes to give macrocycle 169, which came to be known as propdhcene. 

For early examples of helicene based macrocycles, see (a) M. Joey, N. 

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